Patent Publication Number: US-11378614-B2

Title: Temperature detection of power switch using modulation of driver output impedance

Description:
TECHNICAL FIELD 
     This disclosure relates to power switches, and more specifically, techniques and circuits for detecting temperature in power switch circuits. 
     BACKGROUND 
     Power switches are used in a wide variety of applications in order to control power being delivered to a load. A power switch may comprise a Field Effect Transistor (FET), a bipolar junction transistor (BJT), a gallium nitride (GaN) switch, or possibly a silicon-controlled rectifier (SCR). Examples of FETs may include, but are not limited to, junction field-effect transistor (JFET), metal-oxide-semiconductor FET (MOSFET), dual-gate MOSFET, insulated-gate bipolar transistor (IGBT), any other type of FET, or any combination of the same. Examples of MOSFETS may include, but are not limited to, PMOS, NMOS, DMOS, or any other type of MOSFET, or any combination of the same. Examples of BJTs may include, but are not limited to, PNP, NPN, heterojunction, or any other type of BJT, or any combination of the same. 
     Power switches are typically controlled via a modulation control signal, such as pulse width modulation (PWM), pulse frequency modulation (PFM), pulse duration modulation, pulse density modulation, or another type of modulation control signal. Modulation control signals can be applied to a power switch so as to control on/off switching of the power switch, and thereby control the average amount of power delivered through the power switch to a load. The on/off switching of the power switch effectively chops its power delivery up into discrete parts. The average value of voltage and/or current fed to a load can be controlled by turning the switch on and off at a fast rate. The longer the switch is on compared to the off periods, the higher the total power supplied to the load. In many applications, two different power switches are configured in a high-side and low-side configuration, and the on/off switching of the two power switches is synchronized in order to deliver the desired power to a switch node positioned between the high-side and low-side switch. 
     The ability to detect temperature in a power switch is highly desirable. To do so, conventional techniques often use external components, such as negative temperature coefficient (NTC) thermistors or semiconductor-based temperature sensors (e.g., diodes) that are mounted close to the power switch. These external components may be galvanically isolated from the power switch in order to simplify measurements. Unfortunately, these conventional techniques can be imprecise and may result in delayed reactions to temperature-related problems with the switch. For example, external components may measure the temperature of the housing of the switch or a temperature close to the switch with a certain intrinsic delay, but these measurements are not always precisely indicative the temperature of the power switch itself. 
     SUMMARY 
     In general, this disclosure describes several different techniques for detecting temperature in a power switch circuit and controlling the power switch in response to the detection of temperature. The power switch circuit may comprise a power switch and a temperature-dependent circuit element (such as a temperature-dependent resistor or other circuit element that operates with temperature dependence). The temperature-dependent circuit element may be electrically coupled to at least one node of the power switch. A driver circuit for the power switch may be configured to perform useful techniques that facilitate precise temperature detection. Moreover, a variety of driver control techniques are described for controlling the power switch in response to the temperature detection. The control techniques may include local control techniques that can be implemented in logic of the driver circuit, e.g., to disable the power switch or to adjust transition time of the power switch. Additionally or alternatively, the control techniques may include system-level control techniques that may be implemented by a controller of the driver circuit, e.g., to adjust modulation control signals delivered to the power switch. 
     In some examples, this disclosure describes techniques that perform paired measurements of both current and voltage to facilitate precise temperature determinations associated with the power switch. In such examples, the current and voltage measurements may be performed based on timing associated with on/off switching of the power switch. For example, the current and voltage measurements may be performed at specific times when a voltage over the power switch is stable and when the power switch is not in a transition state. The measurements may be paired, in that both the current measurement and the voltage measurement are made in temporal proximity with each other, e.g., within a time window where temperature is unlikely to change in the power switch, or where the voltage does not change significantly between two current measurements (or vice versa). In some examples, the current and voltage measurements can be made within a same switching period of the power switch, although paired measurements could also span multiple switching periods in other examples. In other examples, the current and voltage measurements can be made periodically at precise times during different switching periods of the power switch. The voltage and current measurements may facilitate calculation of input impedance of a temperature-dependent circuit element coupled to at least one node of the power switch, and this input impedance of the temperature-dependent circuit element may be indicative of temperature of the power switch. In any case, the driver circuit may be further configured to control the power switch based at least in part on the current measurement and the voltage measurement. Again, several different control techniques are also described. 
     In other examples, this disclosure describes techniques whereby a driver circuit is configured to modulate its output impedance and perform one or more voltage measurements while modulating the output impedance of the driver circuit. In these examples, the techniques for modulating the output impedance of the driver circuit and performing the one or more voltage measurements may be performed based on timing associated with on/off switching of the power switch, and in some cases, the techniques can be performed periodically during different switching periods of the power switch. For example, modulating the output impedance of the driver circuit and performing the one or more voltage measurements may be performed at specific times when a voltage over the power switch is stable and when the power switch is not in a transition state. By modulating (e.g., adjusting or re-configuring) the output impedance of the driver circuit at a time when the power switch is stable, the driver circuit can be configured to calculate an input impedance of a temperature-dependent circuit element that is coupled to a node of the power switch, based on the one or more voltage measurements and a known ratio when modulating the output impedance of the driver circuit. The input impedance of the temperature-dependent circuit may be indicative of temperature of the power switch. In any case, the driver circuit may be further configured to control the power switch based at least in part on the one or more voltage measurements. Again, several different control techniques are also described. 
     In one example, this disclosure describes a circuit comprising a driver circuit configured to control a power switch circuit that includes a power switch and a temperature-dependent circuit element electrically coupled to at least one node of the power switch. The driver circuit is configured to deliver a modulation signal to a control node of the power switch to control on/off switching of the power switch. In addition, the driver circuit is configured to perform a current measurement and a voltage measurement associated with the temperature-dependent circuit element and control the power switch based at least in part on the current measurement and the voltage measurement. The current measurement and the voltage measurement are performed based on timing associated with the on/off switching of the power switch. 
     In another example, this disclosure describes a method of controlling a power switch circuit including a power switch and a temperature-dependent circuit element electrically coupled to at least one node of the power switch. The method comprises delivering a modulation signal to a control node of the power switch to control on/off switching of the power switch, performing a current measurement associated with the temperature-dependent circuit element, performing a voltage measurement associated with the temperature-dependent circuit element, and controlling the power switch based at least in part on the current measurement and the voltage measurement. 
     In another example, a circuit arrangement comprises a power switch circuit including a power switch and a temperature-dependent circuit element electrically coupled to at least one node of the power switch, and a driver circuit configured to deliver a modulation signal to a control node of the power switch to control on/off switching of the power switch. The driver circuit is configured to perform a current measurement and a voltage measurement associated with the temperature-dependent circuit element and control the power switch based at least in part on the current measurement and the voltage measurement. The current measurement and the voltage measurement are performed based on timing associated with the on/off switching of the power switch. 
     In another example, this disclosure describes a circuit configured to control a power switch circuit that includes a power switch and a temperature-dependent circuit element electrically coupled to at least one node of the power switch. The circuit comprises a driver circuit configured to be coupled to a supply circuit, wherein the driver circuit is configured to deliver a modulation signal to a control node of the power switch to control on/off switching of the power switch. The driver circuit is further configured to modulate an output impedance of the driver circuit at the control node, perform one or more voltage measurements while modulating the output impedance of the driver circuit, and control the power switch based at least in part on the one or more voltage measurements. 
     In another example, this disclosure describes a method of controlling a power switch circuit including a power switch and a temperature-dependent circuit element electrically coupled to at least one node of the power switch. The method comprises delivering a modulation signal to a control node of the power switch to control on/off switching of the power switch, modulating an output impedance of the driver circuit at the control node, performing one or more voltage measurements while modulating the output impedance of the driver circuit, and controlling the power switch based at least in part on the one or more voltage measurements. 
     In another example, a circuit arrangement comprises a power switch circuit including a power switch and a temperature-dependent circuit element electrically coupled to at least one node of the power switch, and a driver circuit configured to be coupled to a supply circuit. The driver circuit is configured to deliver a modulation signal to a control node of the power switch to control on/off switching of the power switch, and the driver circuit is further configured to modulate an output impedance of the driver circuit at the control node, perform one or more voltage measurements while modulating the output impedance of the driver circuit, and control the power switch based at least in part on the one or more voltage measurements. 
     Details of these and other examples are set forth in the accompanying drawings and the description below. Other features, objects, and advantages will be apparent from the description and drawings, and from the claims. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a block diagram of an example circuit arrangement that includes a power switch circuit and a driver circuit configured to perform one or more of the techniques described herein. 
         FIG. 2  is an example circuit diagram of a power switch circuit that includes a power switch and a temperature dependent resistor coupled to at least one node of the power switch. 
         FIG. 3  a block diagram of an example circuit arrangement that includes a power switch circuit and a driver circuit configured to perform one or more of the techniques described herein. 
         FIG. 4  is a block diagram of an example circuit arrangement that includes a driver circuit with a high ohmic path and a low ohmic path, which may be used to modulate the output impedance of the driver circuit consistent with one or more techniques of this disclosure. 
         FIG. 5  is another block diagram of an example circuit arrangement capable of performing paired voltage and current measurements. 
         FIG. 6  is another block diagram of a circuit arrangement consistent with the techniques of this disclosure and including both a low-side power switch and low-side driver circuit, and a high-side power switch and high-side driver circuit. 
         FIG. 7  is a block diagram of an example circuit arrangement that includes a driver circuit capable of modulating its output impedance. 
         FIG. 8  is a block diagram of a circuit arrangement including both a low-side power switch and low-side driver circuit, and a high-side power switch and high-side driver circuit, whereby the driver circuits can modulate to define high output impedance. 
         FIG. 9  is a timing diagram showing example timing of temperature sensing associated with high-side and low-side power switches. 
         FIGS. 10 and 11  are flow diagrams of temperature sensing and control techniques that use paired voltage and current measurements consistent with this disclosure. 
         FIGS. 12 and 13  are flow diagrams of temperature sensing and control techniques that use modulation of driver output impedance and one or more voltage measurements consistent with this disclosure. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  is a block diagram of an example circuit arrangement  100  that includes a power switch circuit  104  and a driver circuit  102  with temperature-dependent control. Power switch circuit  104  may comprise a power switch  108  and a temperature-dependent circuit element  106  coupled to at least one node of power switch  108 . For example, temperature-dependent circuit element  106  may comprise a temperature-dependent resistor coupled between a control node and an output node of power switch  108 . Driver circuit  102  is one example of a driver circuit configured to perform one or more of the techniques described herein. This disclosure describes several different techniques for detecting temperature in a power switch circuit and controlling the power switch in response to the detection of temperature. 
     In some examples, driver circuit  102  may be configured to perform paired measurements of both current and voltage to facilitate precise temperature determinations associated with temperature-dependent circuit element  106  thereby providing an accurate measure of the temperature of power switch circuit  104 . In such examples, driver circuit  102  may be configured to perform the current and voltage measurements based on timing associated with on/off switching of power switch  108 . For example, the current and voltage measurements may be performed at specific times when a voltage over power switch  108  is stable and when power switch  108  is not in a transition state. Driver circuit  102  may perform so-called “paired measurements” of current and voltage, in that both the current measurement and the voltage measurement are made in temporal proximity with each other, e.g., within a time window where temperature is unlikely to change in power switch circuit  104 , or where the voltage does not change significantly between two current measurements (or vice versa). In some examples, driver circuit  102  may be configured to perform the current and voltage measurements within a same switching period of power switch  108 , although paired measurements could also span multiple switching periods in other examples. Moreover, in some cases, the paired measurements can be repeated during successive switching periods of the power switch, e.g., every period or every “Nth” period, where N is a positive integer. In still other cases, the paired measurements can be made in response to a trigger or command from a control circuit. In any case, the voltage and current measurements may facilitate calculation of input impedance of a temperature-dependent circuit element  106 , which is coupled to at least one node of power switch  108 . This input impedance of the temperature-dependent circuit element  106  may be indicative of temperature of power switch  108 . In various examples, driver circuit  102  may be further configured to control power switch  108  based at least in part on the current measurement and the voltage measurement. Again, several different control techniques are also described below. 
     In other examples, driver circuit  102  may be configured to modulate its output impedance and perform one or more voltage measurements while modulating the output impedance of driver circuit  102 . In these examples, modulating the output impedance of the driver circuit  102  and performing the one or more voltage measurements may be performed based on timing associated with on/off switching of power switch  108 . For example, modulating the output impedance of driver circuit  102  and performing the one or more voltage measurements may be performed at specific times when a voltage over power switch  108  is stable and when power switch  108  is not in a transition state. Moreover, in some cases, the modulating the output impedance of driver circuit  102  and performing the one or more voltage measurements can be repeated during successive switching periods of the power switch, e.g., every period or every “Nth” period, where N is a positive integer. In still other cases, the modulating the output impedance of driver circuit  102  and performing the one or more voltage measurements can be made in response to a trigger or command from a control circuit. In any case, by modulating (e.g., adjusting or re-configuring) the output impedance of driver circuit  102  at a time when power switch  108  is stable, driver circuit  102  can calculate an input impedance of temperature-dependent circuit element  106  that is coupled to a node of power switch  108  based on the one or more voltage measurements and a known ratio when modulating the output impedance of driver circuit  102 . The input impedance of the temperature-dependent circuit  106  may be indicative of temperature, thus providing a measure of the temperature of power switch circuit  104 . In any case, driver circuit  102  may be further configured to control power switch  108  based at least in part on the one or more voltage measurements. Again, several different control techniques are also described below. 
       FIG. 2  is an example circuit diagram of a power switch circuit  204  that includes a power switch  205  and a temperature dependent resistor  206  coupled to at least one node of power switch  205 . Power switch  205  may comprise any of a wide variety of transistors used for power delivery, such as a Field Effect Transistor (FET), a bipolar junction transistor (BJT), a gallium nitride (GaN) switch, or possibly a silicon controlled rectifier (SCR). Examples of FETs may include, but are not limited to, junction field-effect transistor (JFET), metal-oxide-semiconductor FET (MOSFET), dual-gate MOSFET, insulated-gate bipolar transistor (IGBT), any other type of FET, or any combination of the same. Examples of MOSFETS may include, but are not limited to, PMOS, NMOS, DMOS, or any other type of MOSFET, or any combination of the same. Examples of BJTs may include, but are not limited to, PNP, NPN, heterojunction, or any other type of BJT, or any combination of the same. 
     Power control circuit  204  may include a control terminal  201  for providing modulation control signals for on/off switching or power switch  205 . Terminals  202  and  203  are labeled as load terminals insofar as a load could be attached to either terminal  202  or terminal  203 , depending on the use and configuration of power switch circuit  204  within a larger system. Current flows from terminal  202  to terminal  203  through power switch  205 , or from terminal  203  to terminal  202  through power switch  205 , depending on the configuration and location of the load. Modulation control signals from a driver circuit can be delivered to control terminal  201  to control on/off switching of power switch  205  so as to deliver current to a load. In the example of a MOSFET, control terminal  201  may comprise a gate, load terminal  202  may comprise a drain, and load terminal  203  may comprise a source. In the example of a BJT, control terminal  201  may comprise a base, load terminal  202  may comprise a collector, and load terminal  203  may comprise an emitter. In some cases, an additional gate resistor  208  (or base resistor for the example of a BGT) may be positioned between the control terminal  201  and the control node of power switch  205 . The internal connection between the control terminal and the semiconductor area also forms series resistance. 
     As shown in  FIG. 2 , power switch circuit  204  includes a temperature-dependent circuit element (such as a temperature-dependent resistor  206  or other temperature-dependent element) electrically coupled to at least one node of power switch  205 . For example, temperature-dependent resistor  206  may be positioned between a control node of power switch  205  and a load node of power switch  205  so as to provide a current path that is positioned in parallel to the current path through power switch  205  from terminal  202  to terminal  203  (or vice versa). According to this disclosure, a driver circuit (not shown in  FIG. 2 ) for power switch  205  may be configured to perform useful techniques that facilitate precise temperature detection of temperature-dependent circuit element  206 , which can provide an accurate indication of the temperature of power switch circuit  204 . Moreover, a variety of driver control techniques are described for controlling the power switch in response to the temperature detection. 
       FIG. 3  is a block diagram of an example circuit arrangement  300  that includes a power switch circuit  304  and a driver circuit  302  configured to perform one or more of the techniques described herein. A driver supply  315  may be configured to provide the necessary power to driver circuit  302 . 
     Driver circuit  302  may be configured to control power switch circuit  304 . Power switch circuit  304  includes power switch  308  and a temperature-dependent circuit element  306  electrically coupled to at least one node of power switch  302 .  FIG. 2  shows one example of a power switch circuit  204  that could correspond to power switch circuit  304  of  FIG. 3 , although other configurations or circuit elements could also be used. In general, driver circuit  302  may include a driver  312  configured to deliver a modulation signal to a control node of power switch  308  to control on/off switching of power switch  308 . Furthermore, driver circuit  302  includes a current sense unit  314  configured to perform a current measurement and a voltage sense unit  316  configured to perform a voltage measurement. The current and voltage measurements performed by current sense unit  314  and voltage sense unit  306  may comprise measurements associated with the temperature-dependent circuit element, and the measurements may be paired, in that both the current measurement and the voltage measurement are made in temporal proximity with each other, e.g., within a time window where temperature is unlikely to change in power switch circuit  304 , or where the voltage does not change significantly between two current measurements (or vice versa. In some examples, the current and voltage measurements performed by current sense unit  314  and voltage sense unit  306  are made within a same switching period of power switch  308 , although paired measurements could also span multiple switching periods in other examples. Accordingly, sometimes measurements can be paired based on extrapolation or known behavior of the circuit, even if the measurements span two or more switching periods. Also, in some cases, paired measurements can be made periodically, e.g., every switching period or every “Nth” switching period, wherein N is a positive integer. Moreover, in some cases, paired measurements can be made in response to a trigger or command to driver circuit  302  from a controller (not shown in  FIG. 3 ). In any case, based on the voltage and current measurements, driver circuit  312  may be configured to calculate an input impedance of temperature-dependent circuit element  306 , and this input impedance of the temperature-dependent circuit element  306  may be indicative of temperature of power switch circuit  304 . Moreover, driver circuit  312  may be further configured to control power switch  308  based at least in part on the current measurement and the voltage measurement. In some cases, driver circuit  312  may control or adjust operation of power switch based on the calculated impedance, and in some cases, additional steps may be performed by map the calculated impedance to an actual temperature, in which case calculated temperature may be used in the control scheme. Either case can result in desirable control of power switch  308  that is responsive or adaptive to temperature. 
     In some examples, the current and voltage measurements performed by current sense unit  314  and voltage sense unit  316  are performed based on timing associated with the on/off switching of the power switch, which is controlled by driver  312 . For example, the current measurement and the voltage measurement performed by current sense unit  314  and voltage sense unit  316  may be performed at one or more times when a voltage over power switch  308  is stable and power switch  308  is not in a transition state. In some examples, driver  312  may determine that the voltage over power switch  308  is stable based on a determination that driver supply voltage from supply  315  is stable. For example, the current measurement and the voltage measurement may be performed at a time when power switch  308  is turned on, stable, and not in a transition state. Alternatively, the current measurement and the voltage measurement performed by current sense unit  314  and voltage sense unit  316  may be performed at a time when power switch  308  is turned off, stable, and not in a transition state, in which case driver  312  may be configured to apply a negative voltage to the control node of power switch  308  during the current measurement and the voltage measurement. In some examples, current sense unit  314  and voltage sense unit  316  may be configured to refrain from sensing when power switch  308  is unstable or operating in a transition state. 
     As mentioned, the current and voltage measurements performed by current sense unit  314  and voltage sense unit  316  may comprise paired measurements. In some cases, circuit arrangement  300  may include memory or storage configured to store the paired measurements. In some examples, the voltage measurement may comprise a measurement of voltage supplied to the driver circuit  302 , e.g., from supply  315 , for driving power switch  308 . In other examples, the voltage measurement may comprise a measurement of voltage drop across temperature-dependent circuit element  306 . As examples, one or more shunt resistors or current mirror circuits may be used by current sense unit  314  to perform current measurements. 
     In some examples, voltage sense unit  316  may be used to measure the voltage of the control node of power switch  308  if the temperature-dependent circuit element  306  is connected to the control node. In some examples, voltage sense unit  316  may be used to measure the voltage of supply unit  315  if the voltage drop over unit  312  between the output of the supply unit  315  and the control node of the power switch is known or close to 0. In other examples, voltage sense unit  316  may be used to measure the voltage at a terminal of temperature-dependent circuit element  306  if the other terminal of element  306  is connected to a load terminal of power switch  308 . 
     A variety of driver control techniques can be used for controlling power switch  308  in response to the temperature detection. In some examples, driver circuit  302  includes logic (not shown in  FIG. 3 ) configured to control power switch  308  in response to the current measurement and the voltage measurement indicating a temperature of the power switch. For example, driver  312  may be configured to respond to one or more temperature-related changes in the operation of the power switch circuit. The logic, for example, may be configured to adjust transition speed of power switch  308  in response to the current measurement and the voltage measurement indicating the temperature of power switch  308 . As another example, the logic may be configured to disable power switch  308  in response to the current measurement and the voltage measurement indicating the temperature of power switch  308 , which may provide device protection. Disabling power switch  308  may include turning off power switch, and in some cases, disabling power switch  308  may also include preventing power switch  308  from being turned on. As noted, in some cases, the circuit response may occur based on a calculation of impedance (e.g., input impedance of temperature-dependent circuit element  306 ) indicating the temperature of power switch  308 . Accordingly, in some examples, logic (not shown in  FIG. 3 ) of driver circuit  302  may be configured to control power switch  308  in response to a calculation of impedance indicating the temperature of the power switch  308 , wherein the calculation of the impedance is based on the current measurement and the voltage measurement. 
     In some examples, current sense unit  314  and voltage sense unit  316  of driver circuit  302  may be configured to perform the current measurement and the voltage measurement within a same switching period of power switch  308 . Moreover, in some examples, current sense unit  314  and voltage sense unit  316  of driver circuit  302  may be configured to perform at least one of the current measurement or the voltage measurement a plurality of times within each switching period of the power switch. In still other cases, current sense unit  314  and voltage sense unit  316  of driver circuit  302  may be configured to perform at least one of the current measurement or the voltage measurement a plurality of times during successive switching periods. Also, in some cases, current sense unit  314  and voltage sense unit  316  of driver circuit  302  may be configured to perform at least one of the current measurement or the voltage measurement in response to a command or trigger from a controller (not shown). Driver circuit  302  may be configured to pair and store paired measurements of current and voltage for use in determining temperature. In some examples, current sense unit  314  and voltage sense unit  316  of driver circuit  302  may be configured to perform at least one current measurement and a plurality of voltage measurements within a same switching period of power switch  308 . 
     Power switch  308  may comprise a so-called “high-side” power switch. In some configurations, a high-side power switch is connected to a so-called “low-side” power switch and the load is coupled to a switch node located between the high-side power switch and the low-side power switch. The techniques of this disclosure may be use for temperature detection and control of a high-side power switch, a low-side power switch, or both a high-side power switch and a low-side power switch. In still further examples, a control unit (e.g., a digital control unit) may be used to control driver  312  and possibly deliver commands or triggers to initiate voltage and current measurements for temperature detection. Also, this disclosure describes configurable parameters that may be used to configure driver circuit  302 , a control unit, or other units. Additional details of exemplary control units, configurability, and other aspects of temperature detection techniques are described in more detail below. 
     As mentioned, temperature-dependent circuit element  306  may comprise a temperature-dependent resistor, although other types of temperature-dependent circuit elements could also be used in accordance with this disclosure. In some cases, temperature-dependent circuit element  306  is electrically coupled to a control node of power switch  308  and a load node of power switch  308  (e.g., coupled between the node at Gint and the node at E shown in the example power switch circuit  204  of  FIG. 2 ). In other examples, however, temperature-dependent circuit element  306  may be electrically coupled to a dedicated sensing node (which may include a dedicated sensing pin) associated with power switch circuit  304  and a load node of power switch  308 . 
       FIG. 4  is a block diagram of an example circuit arrangement  400  that includes a driver circuit  402  comprising a driver  412  that includes both a high ohmic path  418  and a low ohmic path  417 . With this example, driver circuit  402  may be used to modulate the output impedance of the driver  412  in order to facilitate accurate temperature measurements based on a known ratio between the voltages associated with high ohmic path  418 , e.g., by referring to a reference measurement at a given temperature. As examples, the impedance of the temperature-dependent circuit element  406  may be calculated by measuring the voltages at both terminals of the high-ohmic path if the impedance of the high-ohmic path is known (e.g. by trimming or per construction). In some examples, the temperature of the temperature-dependent circuit element can be calculated based on the ratio between the measured voltages associated with the high-ohmic path  418  and a known ratio at a known temperature. 
     As examples, the ratio between the voltage at the gate driver terminal connected to the control node of the power switch and the voltage at the gate driver terminal connected to the gate driver supply may be used as a baseline for the temperature calculation. In this case, the path through the gate driver can be configured as ohmic path forming an ohmic divider with the impedance of the temperature-depending circuit element. In one implementation, both voltages may be measured with one or more analog-to-digital converters (ADC) referring to at least one reference voltage and the ratio can be calculated based on the conversion results. In another implementations, the voltage at the supply input terminal of the gate driver may be used as reference for the measurement of the voltage at the gate driver terminal connected to the control node of the power switch. This technique may be called ratiometric measurement and delivers the ratio between both voltages with a single AD conversion. In this case, the result is always “paired”, because both voltages are taken into account simultaneously by the ADC. If these measurements are done during a teaching phase, e.g. on a tester device during production test with different temperatures, the conversion results can be directly taken as input for a LUT without the need to know or to trim the value of the high-ohmic path. The low-ohmic path may be used to control the control node of the power switch during transitions between switching states of the power switch and to control the transition itself (e.g. the switching speed). The low-ohmic path may be built in a way that that ensures that a voltage measurement over the low-ohmic path does not deliver measurement results that are precise enough for temperature calculation (e.g. impedance of the low-ohmic path&lt;&lt;impedance of the temperature-dependent circuit element). The driver output impedance may be changed from low-ohmic path to high-ohmic path to allow more precise voltage measurements if the voltages over the load terminals of the power switch are stable and not in a transition, because the voltage drop over the high-ohmic path is bigger than the drop over the low-ohmic path (in steady state). 
     Driver circuit  402  may be configured to control a power switch circuit  404  that includes a power switch  408  and a temperature-dependent circuit element  406  electrically coupled to at least one node of power switch  408 . Driver circuit  402  may be configured to be coupled to a supply circuit  415 , and driver circuit  402  may be configured to deliver a modulation signal to a control node of power switch  408  to control on/off switching of power switch  408 . Moreover, driver circuit  402  may be further configured to modulate an output impedance of driver circuit  412  at the control node of power switch  402 . Voltage sense unit  416  of driver circuit  402  may be configured to perform one or more voltage measurements while driver circuit  412  modulates the output impedance, and driver circuit  402  may control power switch  408  based at least in part on the one or more voltage measurements. In order to modulate the output impedance of driver circuit  402  at the control node of power switch  408 , driver  412  may include both a low ohmic path  417  from the supply circuit  415  to the control node of power switch  408 , and a high ohmic path  418  from the supply circuit  415  to the control node. One or more switches  413 A and  413 B may be configured to switch driver  412  between the low ohmic path and the high ohmic path. Accordingly, to modulate its output impedance, driver circuit  412  may be configured to switch driver  412  from the low ohmic path  417  to the high ohmic path  418 , and driver circuit  402  may be configured to perform the one or more voltage measurements while driver  412  is configured to define the high ohmic path. 
     The one or more voltage measurements may be performed at the output of driver circuit  402  and may be used to calculate an input impedance of the temperature-dependent circuit element  406 . As examples, both, the low-ohmic path and the high-ohmic path may be built by a path element that can be configured to change its conductivity, such as a transistor. In this case, the description of the high-ohmic path relates to a first operating condition of the configurable path element and the low-ohmic path to a second operating condition of the same path element. In some examples, the low-ohmic path may be operated as a current source and the high-ohmic path may be operated as a resistive element. In some examples, the low-ohmic path elements may be built with components different from the components of the high-ohmic path. The two switches  413 A and  413 B refer to the activation of the low-ohmic path or of the high-ohmic path. In one implementation, these switches may be used to select the operating conditions leading to a low-ohmic path or a high-ohmic path. In another implementation, these switches may be part of the low-ohmic path and/or of the high-ohmic path. 
     In some cases, voltage sense unit  416  may perform one or more measurements of voltage at the output of driver  412  and driver circuit  402  may use this voltage measurement and known ratio associated with high ohmic path  418  to determine input impedance of temperature dependent circuit element  406 . In this way, driver circuit  402  may be configured to calculate an input impedance of the temperature-dependent circuit element  406  based on the one or more voltage measurements by voltage sense unit  416  and a known ratio when modulating the output impedance of the driver circuit. Low ohmic path  417  may comprise a normal electrical path used when delivering a control signal to power switch  408 , whereas high ohmic path  418  may comprise an alternative path with high electrical resistance that is modulated to the control node of power switch  408  when power switch is stable in order to facilitate temperature determinations based on measured voltage and a known ohmic ratio defined by high ohmic path  418 . A network of one or more resistors may be used to define high ohmic path  418 , although other components could also be used to modulate the output impedance of driver  412 . Other components that could be used for such output impedance modulation, for example, may include one or more analog-to-digital converters, one or more switches, or other electrical elements or components. 
     Driver circuit  412  may be configured to switch from low ohmic path  412  to high ohmic path  418  and cause voltage sense unit  416  to perform the one or more voltage measurements based on timing associated with the on/off switching of the power switch. In some examples, driver circuit  412  is configured to modulate from low ohmic path  417  to high ohmic path  418  and cause voltage sense unit  416  to perform the one or more voltage measurements at a time when power switch  408  is stable and when power switch  408  is not in a transition state. In some examples, driver  412  may determine that the voltage over power switch  408  is stable based on a determination that driver supply voltage from supply  415  is stable. In some cases, the one or more voltage measurements performed by voltage sense unit  416  are performed at a time when power switch  408  is turned on, stable, and not in a transition state. Alternatively, the one or more voltage measurements performed by voltage sense unit  416  may be performed at a time when the power switch is turned off, in which case driver circuit  402  may be configured to apply a negative voltage to the control node of power switch  408  during the one or more voltage measurements. In some examples, voltage sense unit  416  may be configured to refrain from sensing when power switch  408  is unstable or operating in a transition state. 
     In some cases, driver circuit  402  may be configured to modulate from a first configuration defining low ohmic path  417  to a second configuration defining high ohmic path  418  and then perform the one or more voltage measurements a plurality of times within one switching period of the power switch. In other cases, driver circuit  402  may be configured to modulate from low ohmic path  417  to high ohmic path  418  and perform the one or more voltage measurements a plurality of times over successive switching periods of power switch  408  or periodically every Nth period of power switch  408 , where N is a positive integer. Also, in still other cases, driver circuit  402  may be configured to modulate from low ohmic path  417  to high ohmic path  418  and perform the one or more voltage measurements in response to a command or trigger from a control unit (not shown in  FIG. 4 ). In some cases, voltage sense unit  416  may comprise an analog-to-digital converter (ADC) or an analog amplifier or analog comparator. 
     Like the example of  FIG. 3 , with the example of  FIG. 4 , a variety of driver control techniques can be used for controlling power switch  408  in response to the temperature detection. In some examples, driver circuit  402  includes logic (not shown in  FIG. 4 ) configured to control power switch  408  in response the one or more voltage measurements and a known ratio between voltages or a known impedance of the high-ohmic path indicating a temperature of the power switch. For example, driver  412  may be configured to respond to one or more temperature-related changes in the operation of the power switch circuit  404 . The logic, for example, may be configured to adjust transition speed of power switch  408  in response to the one or more the voltage measurements (and the known ratio or impedance) indicating the temperature of power switch  408 . As another example, the logic may be configured to disable power switch  408  in response to the one or more voltage measurements (and the known ratio or impedance) indicating the temperature of power switch  408 , which may provide device protection. Disabling power switch  408  may include turning off power switch, and in some cases, disabling power switch  408  may also include preventing power switch  408  from being turned on. As noted, in some cases, the circuit response may occur based on a calculation of impedance (e.g., input impedance of temperature-dependent circuit element  406 ) or the voltages at the terminals of the high-ohmic path indicating the temperature of power switch  408 . Accordingly, in some examples, logic (not shown in  FIG. 4 ) of driver circuit  402  may be configured to control power switch  408  in response to a calculation of impedance indicating the temperature of the power switch  408 , wherein the calculation of the impedance is based on the voltage measurement and the known ratio associated with high ohmic path  418 . 
     In some examples, voltage sense unit  416  of driver circuit  402  may be configured to perform several voltage measurements within a same switching period of power switch  408 . Moreover, in some examples, voltage sense unit  416  of driver circuit  402  may be configured to perform the voltage measurements a plurality of times within each switching period of power switch  408 . In still other cases, voltage sense unit  416  of driver circuit  402  may be configured to perform the one or more voltage measurements a plurality of times during successive switching periods (e.g., every period or every Nth period). Also, in some cases, voltage sense unit  416  of driver circuit  402  may be configured to perform the one or more voltage measurements in response to a command or trigger from a control unit (not shown in  FIG. 4 ). 
     Like the example of  FIG. 3 , with the example of  FIG. 4 , power switch  408  may comprise a so-called “high-side” power switch. In some configurations, a high-side power switch is connected to a so-called “low-side” power switch and the load is coupled to a switch node located between the high-side power switch and the low-side power switch. The techniques of this disclosure may be use for temperature detection and control of a high-side power switch, a low-side power switch, or both a high-side power switch and a low-side power switch. In still further examples, a control unit (e.g., a digital control unit) may be used to control driver  412  and possibly deliver commands or triggers to initiate output impedance modulation and voltage measurements for temperature detection. Also, this disclosure describes configurable parameters that may be used to configure driver circuit  402 , a control unit, or other units. Additional details of exemplary control units, configurability, and other aspects of temperature detection techniques are described in more detail below. 
     Temperature-dependent circuit element  406  may comprise a temperature-dependent resistor, although other types of temperature-dependent circuit elements could also be used in accordance with this disclosure. In some cases, temperature-dependent circuit element  406  is electrically coupled to a control node of power switch  408  and a load node of power switch  408  (e.g., coupled between the node at Gint and the node at E shown in the example power switch circuit  204  of  FIG. 2 ). In other examples, however, temperature-dependent circuit element  406  may be electrically coupled to a dedicated sensing node associated with power switch circuit  404  and a load node of power switch  408 . 
       FIG. 5  is another block diagram of an example circuit arrangement capable of performing paired voltage and current measurements. Circuit arrangement  500  comprises a power switch circuit  504 , which may be similar to circuit power switch circuit  204  shown in  FIG. 2 . Circuit arrangement  500  also includes a control unit  522 , which may comprise a digital processing unit, such as a microprocessor, ASIC, FPGA, CPLD, or microcontroller. In addition, circuit arrangement  500  includes a gate driver  512 , a gate driver supply  520 , a synchronization unit  524 , a decision unit  526 , a temperature function unit  516  and a voltage and current sensing unit  514 . In some examples, units  512 ,  520 ,  524 ,  526 ,  516  and  514  may be part of a gate driver circuit, although one or more of these units could also be implemented as separate circuits or as part of control unit  522 . 
     Gate driver  512  may be configured to control a power switch within power switch circuit  504 , which also includes a temperature-dependent circuit element electrically coupled to at least one node of the power switch. Again,  FIG. 2  provides additional details on a power switch circuit  204  that may be similar to power switch circuit  504 . Gate driver  512  is configured to deliver a modulation signal to a control node of the power switch within power switch circuit  504  in order to control on/off switching of the power switch. Gate driver supply  520  can provide the necessary power for operation of gate driver  512  and to control the control node of the power switch. Voltage and current sensing unit  514  is configured to perform a current measurement and a voltage measurement associated with the temperature-dependent circuit element within power switch circuit  504 . As described herein, these measurements of voltage and current may be paired and timed according to the switching period associated with on/off switching of the power switch within power switch circuit  504 . 
     In some example, the current and voltage measurements performed by voltage and current sensing unit  514  are made within a same switching period of the power switch within power switch circuit  504 , although paired measurements could also span multiple switching periods in other examples. Also, in some cases, paired measurements can be made periodically by voltage and current sensing unit  514 , e.g., every switching period or every “Nth” switching period, wherein N is a positive integer. Moreover, in some cases, paired measurements can be made in response to a trigger or command to from control unit  522 . In some examples, a filter structure may be used to filter results of several paired measurements to reduce noise effects or distortion of a single measurement. 
     Synchronization unit  524  may deliver measurement trigger signals to voltage and sensing unit  514  to coordinate timing of the paired measurements such that the current measurement and the voltage measurement are performed based on timing associated with the on/off switching of the power switch. Synchronization unit  524  may receive signals (or mirrors of signals) associated with PWM control signals from control unit  522 , which are also delivered to gate driver  512 . In this way, synchronization unit  524  may identify the times when the voltages over the terminals of the power switch within power switch circuit  504  are stable, triggering paired measurements by voltage and sensing unit  514 . Temperature function unit  516  may determine the temperature associated with power switch circuit  504  based on the paired measurements of current and voltage, essentially applying Ohm&#39;s Law to calculate for impedance of the temperature-dependent circuit element based on measured voltage and current over and through the temperature-dependent circuit element. In some cases, the calculated impedance itself may be used as an indicator of temperature, and in other cases, the calculated impedance can be mapped to temperature, such as via a mathematical equation or a lookup table (LUT). In any case, temperature function unit  516  may provide a temperature indication to decision unit  526 . 
     Decision unit  526  may be configured to cause driver-level or system-level reactions to temperature, or both driver-level and system-level reactions. Driver-level reactions may include immediate driver response to temperature, e.g., via logic within gate driver  512 . Such driver-level reactions may include disabling the power switch within power switch circuit  504  in response to temperature, or possibly adjusting (increasing or reducing) transition times associated with the power switch in response to measured temperature, or changing the timing and/or levels of currents or voltages to charge or discharge the control node of the power switch. In some cases, disabling the power switch may include turning off the power switch, and in some cases, disabling the power switch may include disabling the ability to turn the power switch back on. 
     As mentioned, decision unit  526  may also be configured to cause system-level reactions to temperature. System level reactions may include adjustment of PWM control signals, e.g., adjusting the duty cycle, based on measured temperature. Driver-level reactions may be more responsive to temperature changes so as to provide circuit protection based on temperature or adjustment of operating conditions of the power switch. System level reactions be help improve operation of the system at different temperatures. 
     The current and voltage measurements performed by voltage and current sensing unit  514  may be based on timing associated with on/off switching of the power switch within power switch circuit  504 , which are controlled by PWM signals defined by control unit  522  and delivered to power switch circuit  504  by gate driver  512 . As described herein, the current and voltage measurements may be performed at specific times when a voltage over the power switch within power switch circuit  504  is stable and when the power switch is not in a transition state. Moreover, voltage and current sensing unit  514  may refrain from sensing at other times when the power switch within power switch circuit  504  is either unstable or operating in a transition state. Again, the voltage and current measurements may be so-called “paired measurements” of current and voltage, in that both the current measurement and the voltage measurement are made in temporal proximity with each other, e.g., within a time window where temperature is unlikely to change in power switch circuit  504 , or where the voltage does not change significantly between two current measurements (or vice versa). In some examples, voltage and current sensing unit  514  may be configured to perform the current and voltage measurements within a same switching period of the power switch within power switch circuit  504 , although paired measurements could also span multiple switching periods in other examples. Moreover, in some cases, the paired measurements can be repeated during successive switching periods of the power switch, e.g., every period or every “Nth” period, where N is a positive integer. In still other cases, the paired measurements can be made in response to a trigger or command from control unit  522 . In some cases, a user may be able to cause control unit  522  to initiate the trigger, so as to provide the ability for users to measure temperature of power switch circuit  504 , when desired. 
       FIG. 6  is another block diagram consistent with the techniques of this disclosure and including both a low-side power switch circuit and low-side gate driver circuit, and a high-side power switch and high-side driver circuit. The example of  FIG. 6  includes a first power switch circuit  604  and a second power switch circuit  654 , which may be referred to as high-side and low-side power switch circuits. A switch node located between first power switch circuit  604  second power switch circuit  654  delivers power to a load based on on/off switching of the power switches within circuits  604  and  654 . 
     A first gate driver  612  delivers modulation control signals to the high-side power switch within power switch circuit  604 , whereas a second gate driver  642  delivers modulation control signals to the low-side power switch within power switch circuit  654 . Control unit  622  may deliver PWM commands to gate drivers  612  and  642  to coordinate the on/off switching of the high-side and low-side power switches. External gate resistors  621  and  641  may be included between the control terminals of the power switch circuits  604  and  654  and gate drivers  612  and  642 , respectively. These external gate resistors  621  and  641 , for example, may define resistances less than 10 Ohms. Gate driver supplies  620  and  640  may provide the power needed to operate gate drivers  612  and  642 . 
     On the high-side, gate driver  612  may be configured to control a power switch within power switch circuit  604 . In particular, gate driver  612  is configured to deliver a modulation signal to a control node of the power switch within power switch circuit  604  in order to control on/off switching of the power switch. Voltage and current sensing unit  614  is configured to perform a current measurement and a voltage measurement associated with the temperature-dependent circuit element within power switch circuit  604 . As described herein, these measurements of voltage and current may be paired and timed according to the switching period associated with on/off switching of the power switch within power switch circuit  604 . Moreover, the timing of the measurements of voltage and current on the high-side, via voltage and current sensing unit  614  may be coordinated relative to the timing of measurements of voltage and current on the low-side, via voltage and current sensing unit  648 . 
     On the low-side, gate driver  642  may be configured to control a power switch within power switch circuit  654 . In particular, gate driver  642  is configured to deliver a modulation signal to a control node of the power switch within power switch circuit  654  in order to control on/off switching of the power switch. Voltage and current sensing unit  648  is configured to perform a current measurement and a voltage measurement associated with the temperature-dependent circuit element within power switch circuit  654 . As described herein, these measurements of voltage and current may be paired and timed according to the switching period associated with on/off switching of the power switch within power switch circuit  654 . Moreover, the timing of the measurements of voltage and current on the low-side, via voltage and current sensing unit  648  may be coordinated relative to the timing of measurements of voltage and current on the high-side, via voltage and current sensing unit  614 . 
     Again, according to this disclosure, the current and voltage measurements performed by voltage and current sensing unit  614  on the high-side may comprise paired measurements. Similarly, the current and voltage measurements performed by voltage and current sensing unit  648  on the low-side may comprise paired measurements. Also, in some cases, paired measurements can be made periodically by voltage and current sensing units  614  and  648 , e.g., every other switching period or periodically. In some cases, voltage and current sensing units  614  and  648  may perform sensing in a complimentary fashion, e.g., with voltage and current sensing unit  614  operating in one switching period, and voltage and current sensing unit  648  operating in another (different) switching period or with voltage and current sensing unit  614  operating in portion or phase of a switching period, and voltage and current sensing unit  648  operating in another (different) portion or phase of the switching period. 
     Synchronization unit  624  can deliver measurement trigger signals to voltage and current sensing units  614  and  648  to coordinate timing of the paired measurements on the high-side and on the low-side. For both the high-side and the low-side, the current measurement and the voltage measurement may be performed based on timing associated with the on/off switching of the power switches. Synchronization unit  624  may receive signals (or mirrors of signals) associated with PWM control signals from control unit  622 , which are also delivered to gate drivers  612  and  642  in a complementary fashion. In this way, synchronization unit  624  may identify the times when the power switches within power switch circuits  604  or  654  are stable, triggering paired measurements by voltage and sensing unit  614  and by voltage and sensing unit  648 . 
     On the high-side, impedance function unit  636  may determine the impedance of a first temperature-dependent circuit element with power switch circuit  604  based on paired measurements of current and voltage, essentially applying Ohm&#39;s Law to calculate for impedance of the temperature-dependent circuit element based on measured voltage and current over and through the temperature-dependent circuit element. Similarly, on the low-side, impedance function unit  650  may determine the impedance of a second temperature-dependent circuit element with power switch circuit  654  based on paired measurements of current and voltage. 
     The calculated impedance by impedance function units  636  and  648  may be used as an indicator of temperature. Accordingly, impedance function units  636  and  648  may provide signals indicative of impedance calculations to local decision units  630  and  646 , respectively. Local decision units  630  may control logic within gate driver  612  on the high-side to provide immediate driver reactions to temperature. In some cases, logic within gate driver  612  may react to temperature-related changes in circuit operation (e.g., due to high temperature) on the high-side by causing gate driver  612  to disable power the power switch within power switch circuit  604  or to adjust transition time of the power switch within power switch circuit  604 . Similarly, logic within gate driver  642  may react to temperature-related changes in circuit operation (e.g., due to high temperature) on the low-side by causing gate driver  642  to disable power the power switch within power switch circuit  654  or to adjust transition time of the power switch within power switch circuit  654 . 
     In addition, impedance function units  636  and  648  may provide signals indicative of impedance calculations to temperature function units  634  and  652 , respectively. Temperature function units  634  and  652  may apply a mathematical function or lookup tables (LUTs) in order to calculate temperatures based on the measured impedances. The contents of the LUTs may be filled with calculated values or may be filled with values elaborated during reference measurements with known temperatures. Temperature indications can be delivered from temperature function units  634  and  652  (associated with high-side and low-side switches respectively) to system decision criteria unit  632 . System decision criteria unit  632  can then provide signals for system-level reactions to control unit  622  so that control unit can adjust or modify system operation based on the calculated temperatures associated with the high-side and low-side switches, respectively. For example, control unit  622  may adjust PWM signals for first gate driver  612 , second gate driver  642 , or both gate drivers  612 ,  642  based on the calculated temperatures. It may also be possible to eliminate temperature function units  634  and  652 , in some examples, in which case control unit  622  may be configured to adjust the modulation signals based on the determined impedances determined by impedance function units  636  and  650 . From a digital standpoint, however, it is often desirable to program control unit  822  in the temperature domain (rather than impedance domain) even though the calculated input impedance of the temperature-dependent circuit elements may be mathematically related to temperature. 
     In some examples, various units within circuit arrangement  600  may be configurable, e.g., to configure one or more configurable parameters that define circuit operational responses to temperature. A configuration unit  644  (which may be an external programming unit), for example, may be capable of configuring local reaction thresholds defined by local decision criteria units  630  and  646 . Alternatively or additionally, configuration unit  644  may be capable of configuring temperature functions within temperature function units  634  and  652 , such as by defining or configuring lookup tables based on testing. Also, in some examples, configuration unit  644  may be capable of defining one or more system reaction thresholds for system decision criteria unit  632 , such as for example, by defining temperature thresholds where PWM signals should be adjusted. The various configurable parameters, for example, could be derived from tests (e.g. during one or more production tests) and possibly stored in memory associated with the units or controller, such as one-time programmable (OTP) memory, Flash memory, electrically-erasable programmable read only memory (EEPROM) or any type of volatile or non-volatile memory. 
       FIG. 7  is a block diagram of an example circuit arrangement  700  that includes a gate driver circuit  702  that includes both a high ohmic path  742  and a low ohmic path  744 . With this example, gate driver circuit  702  may be used to modulate its output impedance in order to facilitate accurate temperature measurements based on a known ratio of voltages associated with high ohmic path  742 . 
     Gate driver circuit  702  may be configured to control a power switch circuit  704  that includes a power switch and a temperature-dependent circuit element electrically coupled to at least one node of power switch.  FIG. 2  provides additional details on a power switch circuit  204  that may be similar to power switch circuit  704 . 
     Gate driver circuit  702  may be configured to be coupled to a gate driver supply circuit  720 , and gate driver circuit  702  may be configured to deliver a modulation signal to a control node of the power switch within power switch circuit  704  to control on/off switching of the power switch. Moreover, gate driver circuit  702  may be further configured to modulate its output impedance at the control node of the power switch within power switch circuit  704 . In some examples, an external gate resistor  730  may be positioned between gate driver circuit  702  and power switch circuit  704 . For example, external gate resistor  730  may define an impedance of less than 10 Ohms. 
     Voltage check/measurement unit  734  of gate driver circuit  702  may be configured to perform one or more voltage measurements while gate driver circuit  702  modulates the output impedance, and gate driver circuit  702  may control the power switch within power switch circuit  704  based at least in part on the one or more voltage measurements. Voltage check timing unit  732  may be configured to coordinate the output impedance modulation and voltage sensing by controlling switches  713 A and  713 B and providing signals to voltage check/measurement unit  734 . In order to modulate the output impedance of gate driver circuit  702  at the control node of the power switch within power switch circuit  704 , gate driver circuit  702  may include both a low ohmic path  744  from gate driver supply  720  to the control node of the power switch within power switch circuit  704 , and a high ohmic path  744  from gate driver supply  720  to the control node. One or more switches  713 A and  713 B may be configured to switch gate driver circuit  702  between the low ohmic path and the high ohmic path. For example, voltage check timing unit  732  may control switches  713 A and  713 B based on PWM signals to ensure that modulation of the output impedance of gate driver circuit  702  (and the voltage sensing during such modulation) occurs at proper times within PWM periods where the power switch is stable. To modulate its output impedance, voltage check timing unit  732  of gate driver circuit  702  may be configured to switch gate driver circuit  702  from the low ohmic path  744  to the high ohmic path  742 , and voltage check measurement unit  734  may be configured to perform the one or more voltage measurements while gate driver circuit  702  is configured to define the high ohmic path. The one or more voltage measurements may be performed at the output of gate driver circuit  702  and may be used to calculate an input impedance of the temperature-dependent circuit element within power switch circuit  704 . 
     In some cases, voltage check measurement unit  734  may perform one or more measurements of voltages related to gate driver circuit  702  and use this voltage measurements and ratio associated with high ohmic path  742  to determine input impedance of the temperature dependent circuit element within power switch circuit  704 . In this way, gate driver circuit  702  may be configured to calculate an input impedance of the temperature-dependent circuit element within power switch circuit  704  based on the one or more voltage measurements by voltage check measurement unit  734  and a voltage ratio when modulating the output impedance of gate driver circuit  702 . Low ohmic path  744  may comprise a normal electrical path used when delivering a control signal to power switch circuit  704 , whereas high ohmic path  742  may comprise an alternative path with high electrical resistance that is modulated to the control node of power switch circuit  704  when the power switch is stable in order to facilitate temperature determinations based on measured voltage and a known ohmic ratio defined by high ohmic path  742 . A network of one or more resistors may be used to define high ohmic path  742 , although other components could also be used to modulate the output impedance of gate driver circuit  702 . Other components that could be used for such output impedance modulation, for example, may include one or more analog-to-digital converters, one or more switches, or other electrical elements or components. 
     Voltage check timing unit  732  may be configured to switch from low ohmic path  744  to high ohmic path  742  and cause voltage check measurement unit  734  to perform the one or more voltage measurements based on timing associated with the on/off switching of the power switch. In some examples, voltage check timing unit  732  is configured to modulate gate driver circuit  702  from low ohmic path  744  to high ohmic path  742  and cause voltage check measurement unit  734  to perform the one or more voltage measurements at a time when the power switch within power switch circuit  704  is stable and when the power switch is not in a transition state. In some examples, gate driver may determine that the driver supply voltage from gate driver supply  720  is stable. In some examples, voltage check measurement unit  734  may coordinate impedance modulation and voltage sensing based on PWM signals. In some cases, the one or more voltage measurements performed by voltage check measurement unit  734  are performed at a time when the power switch within power switch circuit  704  is turned on, stable, and not in a transition state. Alternatively, the one or more voltage measurements performed by voltage check measurement unit  734  may be performed at a time when the power switch is turned off, in which case gate driver circuit  702  may be configured to apply a negative voltage to the control node of power switch circuit  704  during the one or more voltage measurements. In some examples, voltage check measurement unit  734  may be configured to refrain from sensing when the power switch within power switch circuit  704  is unstable or operating in a transition state. 
     In some cases, gate driver circuit  702  may be configured to modulate from a state defining low ohmic path  744  to a state defining high ohmic path  742  and perform the one or more voltage measurements a plurality of times within one switching period of the power switch. In other cases, gate driver circuit  702  may be configured to modulate from a state defining low ohmic path  744  to a state defining high ohmic path  742  and perform the one or more voltage measurements a plurality of times over successive switching periods of the power switch within power switch circuit  704  or periodically every Nth period of the power switch, where N is a positive integer. Also, in still other cases, gate driver circuit  702  may be configured to modulate from a state defining low ohmic path  744  to a state defining high ohmic path  742  and perform the one or more voltage measurements in response to a command or trigger from a control unit (not shown in  FIG. 7 ). In some cases, voltage check measurement unit  734  may comprise an analog-to-digital converter (ADC) or an analog amplifier or analog comparator. 
     Reaction on result unit  736  may generally represent any of variety of driver control techniques can be used for controlling the power switch within power switch circuit  704  in response to the temperature detection. In some examples, reaction on result unit  736  includes logic configured to control the power switch within power switch circuit  704  in response the one or more voltage measurements and a known ratio indicating a temperature of the power switch. For example, unit  736  may be configured to respond to one or more temperature-related changes in the operation of power switch circuit  704 . The logic, for example, may be configured to adjust transition speed of the power switch within power switch circuit  704  in response to the one or more the voltage measurements (and the known ratio) indicating the temperature of the power switch. As another example, the logic may be configured to disable the power switch within power switch circuit  704  in response to the one or more voltage measurements (and the known ratio) indicating the temperature of the power switch, which may provide device protection. Disabling the power switch may include turning off power switch, and in some cases, disabling the power switch may also include preventing the power switch from being turned on. As noted, in some cases, the circuit response may occur based on a calculation of impedance (e.g., input impedance of the temperature-dependent circuit element within power switch circuit  704 ) indicating the temperature of the power switch within power switch circuit  704 . Accordingly, in some examples, logic within unit  736  may be configured to control the power switch in response to a calculation of impedance indicating the temperature of the power switch, wherein the calculation of the impedance is based on the voltage measurements and the known ratio associated with high ohmic path  742 . In still further examples, reaction on result unit  736  may include a communication channel to a control unit (e.g., a digital microprocessor, FPGA, ASIC, CPLD or microcontroller) in order to allow for system-level responses to temperature. In such cases, the control unit (not shown in  FIG. 7 ) may adjust PWM signals (e.g., adjust duty cycles) based on temperature, which may be sent via signals from unit  736 . 
     In some examples, voltage check measurement unit  734  of gate driver circuit  702  may be configured to perform several voltage measurements within a same switching period of the power switch within power switch circuit  704 . Moreover, in some examples, voltage check measurement unit  734  of gate driver circuit  702  may be configured to perform the voltage measurements a plurality of times within each switching period of the power switch. In some examples, a filter structure may be used to filter results of several paired measurements to reduce noise effects or distortion of a single measurement. In still other cases, voltage check measurement unit  734  of gate driver circuit  402  may be configured to perform the one or more voltage measurements a plurality of times during successive switching periods (e.g., every period or every Nth period). Also, in some cases, voltage check measurement unit  734  of gate driver circuit  702  may be configured to perform the one or more voltage measurements in response to a command or trigger from a controller (not shown). Voltage check measurement unit  734  may be configured to refrain from voltage sensing at times when the power switch within power switch circuit  704  is unstable or in a transition state. 
       FIG. 8  is another block diagram consistent with the techniques of this disclosure and including both a low-side power switch circuit and low-side gate driver circuit, and a high-side power switch and high-side driver circuit. The example of  FIG. 8  includes a first power switch circuit  804  and a second power switch circuit  854 , which may be referred to as high-side and low-side power switch circuits. A switch node located between first power switch circuit  804  second power switch circuit  854  delivers power to a load based on on/off switching of the power switches within circuits  804  and  854 . 
     A first gate driver  812  (which includes the ability to modulate to a high ohmic path) delivers modulation control signals to the high-side power switch within power switch circuit  804 , whereas a second gate driver  842  (which includes the ability to modulate to a high ohmic path) delivers modulation control signals to the low-side power switch within power switch circuit  854 . Control unit  822  may deliver PWM commands to gate drivers  804  and  842  to coordinate the on/off switching of the high-side and low-side power switches. External gate resistors  821  and  841  may be included between the control terminals of the power switch circuits  804  and  854  and gate drivers  812  and  842 , respectively. These external gate resistors  821  and  841 , for example, may define resistances less than 10 Ohms. Gate driver supplies  820  and  840  may provide the power needed to operate gate drivers  812  and  842 . 
     On the high-side, gate driver  812  may be configured to control a power switch within power switch circuit  804 . In particular, gate driver  812  is configured to deliver a modulation signal to a control node of the power switch within power switch circuit  804  in order to control on/off switching of the power switch. Voltage (ratio) sensing unit  814  is configured to perform a voltage measurement associated with the temperature-dependent circuit element within power switch circuit  804 . As described herein, the voltage measurement may be timed according to the switching period associated with on/off switching of the power switch within power switch circuit  804 . According to this disclosure, the voltage measurement by voltage (ratio) sensing unit  814  may be used along with a known ratio associated with a high ohmic path of gate driver  812  to determine input impedance of a temperature dependent circuit element within power switch circuit  804 . Moreover, the timing of the voltage measurement by voltage (ratio) sensing unit  814  (and corresponding modulation to the high ohmic path by gate driver  812 ) on the high-side, may be coordinated relative to the timing of voltage measurements (and corresponding modulation of the driver output impedance) low-side, via voltage (ratio) sensing unit  848 . 
     On the low-side, gate driver  842  may be configured to control a power switch within power switch circuit  854 . In particular, gate driver  842  is configured to deliver a modulation signal to a control node of the power switch within power switch circuit  854  in order to control on/off switching of the power switch. Voltage (ratio) sensing unit  848  is configured to perform a voltage measurement associated with the temperature-dependent circuit element within power switch circuit  854  at a time when the output impedance of gate driver  842  is modulated to a high ohmic path. As described herein, the measurements of voltage (and corresponding modulation of driver output impedance) may be timed according to the switching period associated with on/off switching of the power switch within power switch circuit  854 . Moreover, the timing of the voltage measurements on the low-side, via voltage (ratio) sensing unit  848  may be coordinated relative to the timing of measurements of voltage on the high-side, via voltage (ratio) sensing unit  814 . 
     In some cases, high-side and low-side voltage measurements (and corresponding modulation of driver output impedance) can be made periodically by voltage (ratio) sensing units  814  and  848 , e.g., every other switching period or periodically. In some cases, voltage (ratio) sensing units  814  and  848  may perform sensing in a complimentary fashion, e.g., with voltage (ratio) sensing unit  814  operating in one switching period, and voltage (ratio) sensing unit  848  operating in another (different) switching period. As another example, voltage (ratio) sensing units  814  and  848  may perform sensing in a complimentary fashion, e.g., with voltage (ratio) sensing unit  814  operating in one portion of phase of a switching period, and voltage (ratio) sensing unit  848  operating in another (different) portion or phase of the switching period. 
     Synchronization unit  824  can deliver measurement trigger signals to voltage (ratio) sensing units  814  and  848  to coordinate timing of the voltage measurements on the high-side and on the low-side, e.g., at times with driver output impedance is also modulated to high ohmic paths. For both the high-side and the low-side, the voltage measurement or measurements (and corresponding modulation of driver output impedance) may be performed based on timing associated with the on/off switching of the power switches. Synchronization unit  824  may receive signals (or mirrors of signals) associated with PWM control signals from control unit  822 , which are also delivered to gate drivers  812  and  842  in a complimentary fashion. In this way, synchronization unit  824  may identify the times when the power switches within power switch circuits  804  or  854  are stable and driver output impedance can be modulated, triggering measurements by voltage (ratio) sense unit  814  and by voltage (ratio) sense unit  848 . 
     On the high-side, impedance function unit  836  may determine the impedance of a first temperature-dependent circuit element with power switch circuit  604  based on one or more voltage measurements associated with a high ohmic path of gate driver  812 . Similarly, on the low-side, impedance function unit  850  may determine the impedance a second temperature-dependent circuit element with power switch circuit  854  based on one or more voltage measurements associated with a high ohmic path of gate driver  842 . 
     The calculated impedance by impedance function units  836  and  848  may be used as an indicator of temperature. Accordingly, impedance function units  836  and  848  may provide signals indicative of impedance calculations to local decision units  830  and  846 , respectively. Local decision units  830  may control logic within gate driver  812  on the high-side to provide immediate driver reactions to temperature. In some cases, logic within gate driver  812  may react to temperature-related changes in circuit operation on the high-side by causing gate driver  812  to disable power the power switch within power switch circuit  804  or to adjust transition time of the power switch within power switch circuit  804 . Similarly, logic within gate driver  842  may react to temperature-related changes in circuit operation on the low-side by causing gate driver  842  to disable power the power switch within power switch circuit  854  or to adjust transition time of the power switch within power switch circuit  854 . 
     In addition, impedance function units  836  and  848  may provide signals indicative of impedance calculations to temperature function units  834  and  852 , respectively. Temperature function units  834  and  852  may apply a mathematical function or lookup tables (LUTs) in order to calculate temperatures based on the measured impedances. The contents of the LUTs, for example, may be filled with calculated values or may be filled with values elaborated during reference measurements with known temperatures. Temperature indications can be delivered from temperature function units  834  and  852  (associated with high-side and low-side switches respectively) to system decision criteria unit  832 . System decision criteria unit  832  can then provide signals for system-level reactions to control unit  822  so that control unit can adjust or modify system operation based on the calculated temperatures associated with the high-side and low-side switches, respectively. For example, control unit  822  may adjust PWM signals for first gate driver  812 , second gate driver  842 , or both gate drivers  812 ,  842  based on the calculated temperatures. It may also be possible to eliminate temperature function units  834  and  852 , in some examples, in which case control unit  822  may be configured to adjust the modulation signals based on the determined impedances determined by impedance function units  836  and  850 . From a digital standpoint, however, it is often desirable to program control unit  822  in the temperature domain (rather than impedance domain) even though the calculated input impedance of the temperature-dependent circuit elements may be mathematically related to temperature. Again, if LUTs are used, the data within the LUTs, may be determined using calculated values or may be defined with values elaborated during reference measurements with known temperatures. 
     As with the circuit arrangement  600  of  FIG. 6 , various units within circuit arrangement  800  of  FIG. 8  may be configurable, e.g., to configure one or more configurable parameters that define circuit operational responses to temperature. A configuration unit  844  (which may be an external programming unit), for example, may be capable of configuring local reaction thresholds defined by local decision criteria units  830  and  846 . Alternatively or additionally, configuration unit  844  may be capable of configuring temperature functions within temperature function units  834  and  852 , such as by defining or configuring lookup tables based on testing. Also, in some examples, configuration unit  844  may be capable of defining one or more system reaction thresholds for system decision criteria unit  832 , such as for example, by defining temperature thresholds where PWM signals should be adjusted. The various configurable parameters, for example, could be derived from tests (e.g., during one or more production tests) and possibly stored in memory associated with the units or controller, such as one-time programmable (OTP) memory, Flash memory, electrically-erasable programmable read only memory (EEPROM) or any type of volatile or non-volatile memory. 
     According to this disclosure, in some cases, driver circuits may be configured to determine power switch temperature based on paired measurements of current and voltage at specific times within a switching period of a power switch. In other cases, according to this disclosure, driver circuits may be configured to determine power switch temperature by modulating from a low ohmic path to a high ohmic path so as to modulate the output impedance of the driver circuit and then performing one or more voltage measurements at specific times within a switching period of a power switch. In either of these scenarios, the specific times of sensing may occur a plurality of times within one switching period of the power switch. In other cases, the specific times for sensing may occur a plurality of times over successive switching periods of the power switch or switches, such as every Nth period of power switch  804 , where N is a positive integer. Also, in still other cases, driver circuits may be configured to perform sensing in response to a command or trigger from a control unit. In some examples, a filter structure may be used to filter results of several paired measurements to reduce noise effects or distortion of a single measurement. 
       FIG. 9  is a timing diagram showing one specific timing sequence of temperature sensing of high-side and low-side switches (such as power switch circuits  604  and  654  of  FIG. 6  or power switch circuit  804  and  854  of  FIG. 8 ).  FIG. 9  is merely one example and many other timing sequences for temperature sensing could be used as described herein, based on the on/off switching of power switches. In the specific example of  FIG. 9 , graph  901  shows a switching period of a high-side power switch and graph  902  shows a complimentary switching period of a low-side power switch. For the high-side switch, temperature sensing graph  903  shows sensing events  905 A,  905 B and  905 C. For the low-side switch, temperature sensing graph  904  shows sensing events  906 A,  906 B and  906 C. In this example, the temperature sensing events  905 A,  905 B and  905 C associated with the high-side switch are performed when the high-side switch is stable and conducting and when the low-side switch is stable and not conducting. Furthermore, in this example, the temperature sensing events  906 A,  906 B and  906 C associated with the low-side switch are performed when the low-side switch is stable and conducting and when the high-side switch is stable and not conducting. In some examples, events  905 A,  905 B and  905 C may correspond to a current sensing event and a plurality of voltage sensing events, and events  906 A,  906 B and  906 C may correspond to a current sensing event and a plurality of voltage sensing events. In other examples, events  905 A,  905 B and  905 C may correspond to voltage sensing events that correspond to modulation of driver output impedance on the high-side, and events  906 A,  906 B and  906 C may correspond to voltage sensing events that correspond to modulation of driver output impedance on the low-side. Many other timing schemes could be used to provide sensing events every switching period, sensing events periodically every Nth switching period, sensing events in response to triggers or commands, sensing events that span over multiple switching periods, or timing schemes that are based on the on/off switching of the power switch or power switches. Again, in some examples, a filter structure may be used to filter results of several paired measurements to reduce noise effects or distortion of a single measurement. 
       FIGS. 10 and 11  are two exemplary flow diagrams of temperature sensing and control techniques that use paired voltage and current measurements consistent with this disclosure.  FIG. 10  will be described from the perspective of driver circuit  304  of circuit arrangement  300  in  FIG. 3 , although other circuits or circuit arrangements could also be used to perform the technique of  FIG. 10 .  FIG. 10  is one example of a method of method of controlling a power switch circuit  304  including a power switch  308  and a temperature-dependent circuit element  306  electrically coupled to at least one node of the power switch. As shown in  FIG. 10 , driver  312  of driver circuit  302  delivers a modulation signal to a control node of power switch  308  to control on/off switching of the power switch  308  ( 1001 ). Current sense unit  314  performs a current measurement associated with the temperature-dependent circuit element  306  ( 1002 ), and voltage sense unit  314  performs a voltage measurement associated with the temperature-dependent circuit element  306  ( 1003 ). The current and voltage measurements may be paired and may be based on a timing sequence of the on/off switching of power switch  308 , e.g., performed at times with power switch  308  is stable and not in a transition state. Driver circuit  312  may then control power switch  308  based at least in part on the current measurement and the voltage measurement ( 1004 ). In some examples, controlling the power switch may comprise controlling the power switch circuit in response to the current measurement and the voltage measurement indicating a temperature of the power switch. In some examples, the method of  FIG. 10  may further include steps of calculating an impedance (e.g., an input impedance of temperature-dependent circuit element  306 ) based on the current measurement and the voltage measurement and controlling the power switch based on the calculated impedance. In some examples, the method of  FIG. 10  may further include steps determining a temperature of the power switch based on the current measurement and the voltage measurement, wherein controlling the power switch comprises adjusting the modulation signal via a controller based on the determined temperature. Many other details described above could also be applied within the method shown in  FIG. 10 . 
       FIG. 11  is another flow diagram of temperature sensing and control techniques that use paired voltage and current measurements consistent with this disclosure.  FIG. 11  will be described from the perspective of circuit arrangement  600  in  FIG. 6 , although other circuits or circuit arrangements could also be used to perform the technique of  FIG. 11 . 
     According to  FIG. 11 , an external configuration and calibration unit  644  may be used to configure parameters of one or more units within circuit arrangement  600  ( 1001 ), such logic associated with local decision criteria  630 , LUTs or mathematical equations applied by temperature function unit  634  and/or system decision criteria applied by unit  632 . The ability to configure circuit arrangement  600 , e.g., during manufacturing and testing phases, may be highly desirable so that circuit arrangement  600  can be tuned for different uses and applications (e.g., for controlling different types of loads or load arrangements in various different settings). 
     In operation, gate driver  612  delivers a modulation control signal to a control terminal of power switch circuit  604 , e.g., through external gate resistor  621  ( 1102 ), which may control on/off switching of the power switch within power switch circuit  604 . Voltage and current sensing unit  614  performs one or more voltage measurements based on timing of the modulation signal ( 1104 ) and performs one or more current measurements based on timing of the modulation signal ( 1105 ), which may define paired measurements for use in temperature determination and control. With the example of  FIG. 11 , logic within local decision criteria unit  630  may be configured to disable operation of the power switch within power switch circuit  604  if the measurements indicate a temperature related change in circuit operation ( 1105 ). A temperature-related change in circuit operation, for example, may be indicated by high temperature which may be defined or determined locally (e.g., by driver circuitry) via an impedance indication calculated by impedance function unit  636 . The calculated impedance, for example, may comprise a measure of the input impedance of the temperature-dependent circuit element within power switch circuit  604 , which may map to a temperature estimate of power switch circuit  604 . This local response to temperature (via response to an impedance calculation) may be faster than a system response, so as to provide circuit and system protection against temperature changes in circuit operation. In addition to this immediate local response, the method of  FIG. 11  may also facilitate a system response to temperature, which may be a more gradual and preventative action over time to help avoid overheating before it occurs. For example, temperature function unit  636  may determine a temperature indication based on the current and voltage measurement ( 1106 ), such as by applying a LUT to map a calculated impedance to the temperature indication. Since the calculated impedance is based on the paired current and voltage measurements, the temperature indication is also ultimately based on the paired measurements. In other examples, calculated impedance could also be used to cause system-level reactions, but it may be desirable to use temperature for system-level configuration, and hence it may be desirable to map the calculated impedance to the temperature indication via temperature function unit  634 . Control unit  622  can then adjust the modulation signal based on the determined temperature ( 1107 ), e.g., by increasing or decreasing the duty cycle, which again, may allow for predictive or preventive protection against upward temperature trends. These steps as well as many other details described above could also be applied within the method shown in  FIG. 11 . 
       FIGS. 12 and 13  are flow diagrams of temperature sensing and control techniques that use modulation of driver output impedance and one or more voltage measurements consistent with this disclosure.  FIG. 12  will be described from the perspective of driver circuit  404  of circuit arrangement  400  in  FIG. 4 , although other circuits or circuit arrangements could also be used to perform the technique of  FIG. 12 .  FIG. 12  is one example of a method of method of controlling a power switch circuit  404  including a power switch  408  and a temperature-dependent circuit element  406  electrically coupled to at least one node of the power switch. As shown in  FIG. 12 , driver  412  of driver circuit  402  delivers a modulation signal to a control node of power switch  408  to control on/off switching of the power switch  408  ( 1001 ). Driver  412  modulates its output impedance at the control node ( 1202 ), such as by switching from low ohmic path  417  to high ohmic path  418 . Low ohmic path  417  and high ohmic path  418  may comprise alternative electrical paths through driver circuit  412  to the control node of the power switch  408  within power switch circuit  404 . Alternatively, low ohmic path  417  and high ohmic path  418  could be defined by a common path with different operating conditions. In any case, while driver  412  defines the high ohmic path  418 , voltage sense unit  416  performs one or more voltage measurements ( 1203 ). As described herein, switching the path of driver circuit  412  from low ohmic path  417  to high ohmic path  418  and performing the one or more voltage measurements may be performed according to a timing sequence that is based on timing associated with the on/off switching of power switch  408 , e.g., at a time when power switch  408  is stable and when power switch  408  is not in a transition state 
     Driver circuit  412  may control power switch  408  based at least in part on the one or more voltage measurements ( 1204 ). For example, the one or more voltage measurements in combination with a known ratio associated with high ohmic path  418  can be used by driver  412  to determine input impedance of temperature-dependent circuit element  406 , and this input impedance or voltage ratio may be indicative of temperature of power switch circuit  404 . 
     In some examples, controlling the power switch may comprise controlling the power switch circuit in response to the one or more voltage measurements (and the ratio) indicating a temperature of the power switch. In some examples, the method of  FIG. 12  may further include steps of calculating an impedance (e.g., an input impedance of temperature-dependent circuit element  406 ) based on the voltage measurement (and the ratio) and controlling the power switch based on the calculated impedance or voltage ratio. In some examples, the method of  FIG. 12  may further include steps determining a temperature of the power switch based on the one or more voltage measurements, wherein controlling the power switch comprises adjusting the modulation signal via a controller based on the determined temperature. Many other details described above could also be applied within the method shown in  FIG. 12 . 
       FIG. 13  is another flow diagram of temperature sensing and control techniques that use modulation of driver output impedance and one or more voltage measurements consistent with this disclosure.  FIG. 13  will be described from the perspective of circuit arrangement  800  in  FIG. 6 , although other circuits or circuit arrangements could also be used to perform the technique of  FIG. 13 . 
     According to  FIG. 13 , an external configuration and calibration unit  844  may be used to configure parameters of one or more units within circuit arrangement  800  ( 1301 ), such logic associated with local decision criteria  830 , LUTs or mathematical equations applied by temperature function unit  834  and/or system decision criteria applied by unit  832 . The ability to configure circuit arrangement  800 , e.g., during manufacturing and testing phases, may be highly desirable so that circuit arrangement  800  can be tuned for different uses and applications (e.g., for controlling different types of loads or load arrangements in various different settings). 
     In operation, gate driver  812  delivers a modulation control signal to a control terminal of power switch circuit  804 , e.g., through external gate resistor  821  ( 1302 ), which may control on/off switching of the power switch within power switch circuit  804 . Gate driver  812  modulates to a high ohmic path so as to modulate the output impedance of the gate driver  812  at the control node of the power switch associated with power switch circuit  804  ( 1303 ). Voltage (ratio) sensing unit  814  performs one or more voltage measurements based on timing of the modulation signal ( 1304 ) while gate driver  812  modulates its output impedance to the high ohmic path to define the high driver output impedance. The timing of modulating the output impedance of gate driver  812  ( 1303 ) and performing the one or more voltage measurements ( 1304 ) may be based on timing of the modulation control signal that defines on/off switching of the power switch within power switch circuit  804 , e.g., at times with the power switch is stable and not in a transition state. 
     Similar to the example of  FIG. 11 , with the example of  FIG. 13 , logic within local decision criteria unit  830  may be configured to disable operation of the power switch within power switch circuit  804  if the measurements indicate a temperature related change in circuit operation ( 1305 ). A temperature-related change in circuit operation, for example, may be indicated by high temperature which may be defined or determined locally (e.g., by driver circuitry) via an impedance indication calculated by impedance function unit  836 . The calculated impedance, for example, may comprise a measure of the input impedance of the temperature-dependent circuit element within power switch circuit  804 , which may map to a temperature estimate of power switch circuit  804 . This local response to temperature (via response to an impedance calculation) may be faster than a system response, so as to provide circuit and system protection against temperature related changes in circuit operation. In addition to this immediate local response, the method of  FIG. 13  may also facilitate a system response to temperature, which may be a more gradual and preventative action over time to help avoid overheating before it occurs. For example, temperature function unit  836  may determine a temperature indication based on the current and voltage measurement ( 1306 ), such as by applying a LUT to map a calculated impedance or voltage ratio to the temperature indication. Since the calculated impedance or voltage ratio are based on the paired measurements, the temperature indication is also ultimately based on the paired measurements. In other examples, calculated impedance or voltage ratio could also be used to cause system-level reactions, but it may be desirable to use temperature for system-level configuration, and hence it may be desirable to map the calculated impedance or voltage ratio to the temperature indication via temperature function unit  834 . Control unit  822  can then adjust the modulation signal based on the determined temperature ( 1107 ), e.g., by increasing or decreasing the duty cycle, which again, may allow for predictive or preventive protection against upward temperature trends. These steps as well as many other details described above could also be applied within the method shown in  FIG. 13 . 
     The following examples may illustrate one or more aspects of the disclosure. 
     Example 1 
     A circuit comprising a driver circuit configured to control a power switch circuit that includes a power switch and a temperature-dependent circuit element electrically coupled to at least one node of the power switch: wherein the driver circuit is configured to deliver a modulation signal to a control node of the power switch to control on/off switching of the power switch, wherein the driver circuit is configured to perform a current measurement and a voltage measurement associated with the temperature-dependent circuit element and control the power switch based at least in part on the current measurement and the voltage measurement, and wherein the current measurement and the voltage measurement are performed based on timing associated with the on/off switching of the power switch. 
     Example 2 
     The circuit of example 1, wherein the current measurement and the voltage measurement are performed at a time when a voltage over the power switch is stable and the power switch is not in a transition state. 
     Example 3 
     The circuit of example 1 or 2, wherein the current measurement and the voltage measurement are performed at a time when the power switch is turned on. 
     Example 4 
     The circuit of example 1 or 2, wherein the current measurement and the voltage measurement are performed at a time when the power switch is turned off, and wherein the driver circuit is configured to apply a negative voltage to the control node during the current measurement and the voltage measurement. 
     Example 5 
     The circuit of any of examples 1-4, wherein the current measurement and the voltage measurement are paired measurements. 
     Example 6 
     The circuit of claim  5 , wherein the circuit is configured to store the paired measurements. 
     Example 7 
     The circuit of any of examples 1-6, wherein the voltage measurement comprises a measurement of voltage supplied to the driver circuit for driving the power switch. 
     Example 8 
     The circuit of any of examples 1-6, wherein the voltage measurement comprises a measurement of voltage drop across the temperature dependent circuit element. 
     Example 9 
     The circuit of any of examples 1-8, wherein the driver circuit includes logic configured to control the power switch in response to the current measurement and the voltage measurement indicating a temperature of the power switch. 
     Example 10 
     The circuit of example 9, wherein the logic is configured to adjust transition speed of the power switch in response to the current measurement and the voltage measurement indicating the temperature of the power switch. 
     Example 11 
     The circuit of example 9 or 10, wherein the logic is configured to disable the power switch in response to the current measurement and the voltage measurement indicating the temperature of the power switch. 
     Example 12 
     The circuit of any of examples 9-11, wherein the logic is configured to control the power switch in response to a calculation of impedance indicating the temperature of the power switch, wherein the calculation of the impedance is based on the current measurement and the voltage measurement. 
     Example 13 
     The circuit of example 12, the circuit further comprising a control unit configured to adjust the modulation signal based on the determined impedance. 
     Example 14 
     The circuit of any of examples 1-13, wherein the driver circuit includes a temperature unit configured to determine a temperature of the power switch based on the current measurement and the voltage measurement. 
     Example 15 
     The circuit of example 14, wherein the temperature unit comprises a lookup table, wherein inputs to the lookup table are the current measurement and the voltage measurement. 
     Example 16 
     The circuit of any of examples 1-14, wherein the circuit further comprises a control unit configured to adjust the modulation signal based on a determined temperature. 
     Example 17 
     The circuit of any of examples 1-16, wherein the driver circuit includes logic configured to control the power switch in response to the current measurement and the voltage measurement indicating the temperature of the power switch. 
     Example 18 
     The circuit of example 17, wherein the logic is configurable via an external configuration unit that adjusts one or more configurable parameters. 
     Example 19 
     The circuit of any of examples 14-18, wherein the temperature unit is configurable via the external configuration unit that adjusts the one or more configurable parameters. 
     Example 20 
     The circuit of any of examples 13-19, wherein the control unit is configurable via the external configuration unit that adjusts the one or more configurable parameters. 
     Example 21 
     The circuit of any of examples 1-20, wherein the driver circuit is configured to perform the current measurement and the voltage measurement within a same switching period of the power switch. 
     Example 22 
     The circuit of any of examples 1-21, wherein the driver circuit is configured to perform at least one of the current measurement or the voltage measurement a plurality of times within each switching period of the power switch. 
     Example 23 
     The circuit of any of examples 1-22, wherein the driver circuit is configured to perform at least one current measurement and a plurality of voltage measurements within a same switching period of the power switch. 
     Example 24 
     The circuit of any of examples 1-23, wherein the power switch circuit comprises a high-side power switch circuit, the power switch comprises a high-side power switch, the temperate-dependent circuit element comprises a first temperate dependent circuit element, the modulation signal comprises a high-side modulation signal, and the driver circuit comprises a high-side driver circuit, the circuit further comprising: a low-side driver circuit configured to deliver a low-side modulation signal to a control node of a low-side power switch to control on/off switching of the low-side power switch, wherein the low-side driver circuit is further configured to perform a current measurement and a voltage measurement associated with a second temperature-dependent circuit element and control the low-side power switch based at least in part on the current measurement and the voltage measurement associated with the second temperature-dependent circuit element. 
     Example 25 
     The circuit of example 24, wherein the current measurement and the voltage measurement performed by the high-side driver circuit are performed when both the high-side switch and the low-side switch are stable, one of the high-side switch and the low-side switch are on, and one of the high-side switch and the low-side switch are off. 
     Example 26 
     The circuit of example 24 or 25, wherein the current measurement and the voltage measurement performed by the low-side driver circuit are performed when both the high-side switch and the low-side switch are stable, one of the high-side switch and the low-side switch are on, and one of the high-side switch and the low-side switch are off. 
     Example 27 
     A method of controlling a power switch circuit including a power switch and a temperature-dependent circuit element electrically coupled to at least one node of the power switch, the method comprising: delivering a modulation signal to a control node of the power switch to control on/off switching of the power switch; performing a current measurement associated with the temperature-dependent circuit element; performing a voltage measurement associated with the temperature-dependent circuit element; and controlling the power switch based at least in part on the current measurement and the voltage measurement. 
     Example 28 
     The method of example 27, further comprising: performing the current measurement and the voltage measurement according to a timing sequence that is based on timing associated with the on/off switching of the power switch. 
     Example 29 
     The method of example 27 or 28, wherein controlling the power switch comprises: controlling the power switch circuit in response to the current measurement and the voltage measurement indicating a temperature of the power switch. 
     Example 30 
     The method of any of examples 27-29, further comprising: calculating an impedance based on the current measurement and the voltage measurement and controlling the power switch based on the calculated impedance. 
     Example 31 
     The method of any of example 27-30, further comprising: determining a temperature of the power switch based on the current measurement and the voltage measurement, wherein controlling the power switch comprises adjusting the modulation signal via a controller based on the determined temperature. 
     Example 32 
     The method of any of examples 27-31, wherein performing the current measurement and the voltage measurement comprises: performing the current measurement and the voltage measurement in a paired manner. 
     Example 33 
     The method of example 32, wherein performing the current measurement and the voltage measurement in the paired manner comprises performing the current measurement and the voltage measurement within a same switching period of the power switch. 
     Example 34 
     The method of any of examples 27-33, further comprising: configuring one or more parameters associated with controlling the power switch circuit, wherein the one or more parameters define one or more temperature-dependent functions associated with controlling the power switch. 
     Example 35 
     A circuit arrangement comprising: a power switch circuit including a power switch and a temperature-dependent circuit element electrically coupled to at least one node of the power switch; and a driver circuit configured to deliver a modulation signal to a control node of the power switch to control on/off switching of the power switch, wherein the driver circuit is configured to perform a current measurement and a voltage measurement associated with the temperature-dependent circuit element and control the power switch based at least in part on the current measurement and the voltage measurement, and wherein the current measurement and the voltage measurement are performed based on timing associated with the on/off switching of the power switch. 
     Example 36 
     The circuit arrangement of example 35, wherein the temperature-dependent circuit element comprises a temperature-dependent resistor. 
     Example 37 
     The circuit arrangement of example 35 or 36, wherein the temperature-dependent circuit element is electrically coupled to the control node of the power switch and a load node of the power switch. 
     Example 38 
     The circuit arrangement of any of examples 35-37, wherein the temperature-dependent circuit element is electrically coupled to a dedicated sensing node associated with the power switch circuit and a load node of the power switch. 
     Example 39 
     The circuit arrangement of any of examples 35-38, wherein the driver circuit includes an analog to digital converter configured to perform the current measurement. 
     Example 40 
     The circuit arrangement of any of examples 35-39, wherein the driver circuit includes a shunt resistor configured to perform the current measurement. 
     Example 41 
     A circuit configured to control a power switch circuit that includes a power switch and a temperature-dependent circuit element electrically coupled to at least one node of the power switch, the circuit comprising: a driver circuit configured to be coupled to a supply circuit, wherein the driver circuit is configured to deliver a modulation signal to a control node of the power switch to control on/off switching of the power switch, wherein the driver circuit is further configured to modulate an output impedance of the driver circuit at the control node, perform one or more voltage measurements while modulating the output impedance of the driver circuit, and control the power switch based at least in part on the one or more voltage measurements. 
     Example 42 
     The circuit of example 41, wherein the driver circuit is configured to calculate an input impedance of the temperature-dependent circuit element based on the one or more voltage measurements when modulating the output impedance of the driver circuit. 
     Example 43 
     The circuit of example 41 or 42, wherein the driver circuit includes: a low ohmic path from the supply circuit to the control node; and a high ohmic path from the supply circuit to the control node; wherein one or more control signals are configured to switch the driver circuit between the low ohmic path and the high ohmic path, wherein to modulate the output impedance, the driver circuit is configured to switch from the low ohmic path to the high ohmic path, and wherein the driver circuit is configured to perform the one or more voltage measurements while the driver circuit is configured to define the high ohmic path, wherein the one or more voltage measurements are associated with an input impedance of the temperature-dependent circuit element. 
     Example 44 
     The circuit of example 43, wherein driver circuit is configured to switch from the low ohmic path to the high ohmic path and perform the one or more voltage measurements based on timing associated with the on/off switching of the power switch. 
     Example 45 
     The circuit of example 43 or 44, wherein the driver circuit is configured to switch from the low ohmic path to the high ohmic path and perform the one or more voltage measurements at a time when the power switch is stable and the power switch is not in a transition state. 
     Example 46 
     The circuit of any of examples 41-45, wherein the one or more voltage measurements are performed at a time when the power switch is turned on. 
     Example 47 
     The circuit of any of examples 41-45, wherein the one or more voltage measurements are performed at a time when the power switch is turned off, and wherein the driver circuit is configured to apply a negative voltage to the control node during the one or more voltage measurements. 
     Example 48 
     The circuit of any of examples 43-47, wherein driver circuit is configured to switch from the low ohmic path to the high ohmic path and perform the one or more voltage measurements a plurality of times within one switching period of the power switch. 
     Example 49 
     The circuit of any of examples 41-48, wherein the driver circuit includes a temperature unit configured to determine a temperature of the power switch based on the one or more voltage measurements. 
     Example 50 
     The circuit of example 49, wherein the temperature unit comprises a lookup table, wherein inputs to the lookup table are based on the one or more voltage measurements. 
     Example 51 
     The circuit of any of examples 41-50, wherein the circuit further comprises a control unit configured to adjust the modulation signal based on a determined temperature. 
     Example 52 
     The circuit of any of examples 41-51, wherein the driver circuit includes logic configured to control the power switch in response to the voltage measurement indicating a temperature of the power switch. 
     Example 53 
     The circuit of example 52, wherein the logic is configured to adjust a transition speed of the power switch in response to the one or more voltage measurements. 
     Example 54 
     The circuit of example 52 or 53, wherein the logic is configured to disable the power switch in response to the one or more voltage measurements. 
     Example 55 
     The circuit of any of examples 52-54, wherein the logic is configured to control the power switch in response to a calculation of input impedance of the temperature-dependent circuit element, wherein the calculation of input impedance is based on the one or more voltage measurements when modulating the output impedance of the driver circuit. 
     Example 56 
     The circuit of any of examples 52-55, wherein the logic is configurable via an external configuration unit that adjusts one or more configurable parameters. 
     Example 57 
     The circuit of example 49, wherein the temperature unit is configurable via the external configuration unit that adjusts the one or more configurable parameters. 
     Example 58 
     The circuit of example 51, wherein the control unit is configurable via the external configuration unit that adjusts the one or more configurable parameters. 
     Example 59 
     The circuit of any of examples 41-58, wherein the power switch circuit comprises a high-side power switch circuit, the power switch comprises a high-side power switch, the supply circuit comprises a high-side supply circuit, the temperate-dependent circuit element comprises a first temperate dependent circuit element, and the driver circuit comprises a high-side driver circuit, and the circuit further comprising: a low-side driver circuit configured to be coupled to a low-side supply circuit, wherein the low-side driver circuit is configured to deliver a modulation to a control node of a low-side power switch to control on/off switching of the low-side power switch, wherein the low-side driver circuit is further configured to modulate an output impedance of the low-side driver circuit at the control node, perform one or more voltage measurements while modulating the output impedance of the low-side driver circuit, and control the low-side power switch based at least in part on the one or more voltage measurements. 
     Example 60 
     A method of controlling a power switch circuit including a power switch and a temperature-dependent circuit element electrically coupled to at least one node of the power switch, the method comprising: delivering a modulation signal to a control node of the power switch to control on/off switching of the power switch; modulating an output impedance of the driver circuit at the control node; performing one or more voltage measurements while modulating the output impedance of the driver circuit; and controlling the power switch based at least in part on the one or more voltage measurements. 
     Example 61 
     The method of example 60, further comprising: calculating an input impedance of the temperature-dependent circuit element based on the one or more voltage measurements when modulating the output impedance of the driver circuit. 
     Example 62 
     The method of example 60 or 61, wherein modulating the output impedance comprises switching a path of the driver circuit that delivers the modulation signal from a low ohmic path to a high ohmic path, wherein the low ohmic path and the high ohmic paths are alternative electrical paths through the driver circuit to the control node. 
     Example 63 
     The method of any of examples 60-62, further comprising: switching the path of the driver circuit and performing the one or more voltage measurements according to a timing sequence that is based on timing associated with the on/off switching of the power switch. 
     Example 64 
     The method of any of examples 60-63, further comprising switching the path of the driver circuit and performing the one or more voltage measurements at a time when the power switch is stable and the power switch is not in a transition state. 
     Example 65 
     The method of any of examples 60-64, further comprising: switching the path of the driver circuit and performing the one or more voltage measurements a plurality of times within a switching period of the power switch. 
     Example 66 
     The method of any of examples 60-65, wherein modulating the output impedance comprises switching a path of the driver circuit that delivers the modulation signal from a low ohmic path to a high ohmic path, wherein the low ohmic path and the high ohmic paths are defined by a common path with different operating conditions. 
     Example 67 
     The method of any of examples 60-66, further comprising: controlling the power switch based at least in part on the one or more voltage measurements. 
     Example 68 
     The method of any of examples 60-67, wherein controlling the power switch based in part on the one or more voltage measurements comprises disabling the power switch via logic of a driver circuit in response to the one or more voltage measurements. 
     Example 69 
     The method of any of examples 60-68, wherein controlling the power switch based in part on the one or more voltage measurements comprises adjusting a transition speed of the power switch in response to the voltage measurement indicating a temperature of the power switch. 
     Example 70 
     The method of any of examples 60-69, further comprising: determining a temperature of the power switch based on the one or more voltage measurements. 
     Example 71 
     The method of any of examples 60-70, wherein controlling the power switch based in part on the one or more voltage measurements comprises adjusting the modulation signal via a controller based on a determined temperature. 
     Example 72 
     The method of any of examples 60-71, further comprising: configuring one or more parameters associated with controlling the power switch circuit, wherein the one or more parameters define one or more temperature-dependent functions associated with controlling the power switch. 
     Example 73 
     A circuit arrangement comprising: a power switch circuit including a power switch and a temperature-dependent circuit element electrically coupled to at least one node of the power switch; and a driver circuit configured to be coupled to a supply circuit, wherein the driver circuit is configured to deliver a modulation signal to a control node of the power switch to control on/off switching of the power switch, wherein the driver circuit is further configured to modulate an output impedance of the driver circuit at the control node, perform one or more voltage measurements while modulating the output impedance of the driver circuit, and control the power switch based at least in part on the one or more voltage measurements. 
     Example 74 
     The circuit arrangement of example 73, wherein the driver circuit is configured to calculate an input impedance of the temperature-dependent circuit element based on the one or more voltage measurements when modulating the output impedance of the driver circuit. 
     Example 75 
     The circuit arrangement of example 73 or 74, wherein the driver circuit includes: a low ohmic path from the supply circuit to the control node; and a high ohmic path from the supply circuit to the control node; wherein one or more control signals are configured to switch the driver circuit between the low ohmic path and the high ohmic path, wherein to modulate the output impedance, the driver circuit is configured to switch from the low ohmic path to the high ohmic path, and wherein the driver circuit is configured to perform the one or more voltage measurements while the driver circuit is configured to define the high ohmic path, wherein the one or more voltage measurements are associated with an input impedance of the temperature-dependent circuit element. 
     Example 76 
     The circuit arrangement of example 75, wherein driver circuit is configured to switch from the low ohmic path to the high ohmic path and perform the one or more voltage measurements based on timing associated with the on/off switching of the power switch. 
     Example 77 
     The circuit arrangement example 75 or 76, wherein the driver circuit is configured to switch from the low ohmic path to the high ohmic path and perform the one or more voltage measurements at a time when the power switch is stable and the power switch is not in a transition state. 
     Example 78 
     The circuit arrangement of any of examples 73-77, wherein the temperature-dependent circuit element comprises a temperature-dependent resistor. 
     Example 79 
     The circuit arrangement of any of examples 73-78, wherein the temperature-dependent circuit element is electrically coupled to the control node of the power switch and a load node of the power switch. 
     Example 80 
     The circuit arrangement of any of examples 73-78, wherein the temperature-dependent circuit element is electrically coupled to a dedicated sensing node associated with the power switch circuit and a load node of the power switch. 
     Example 81 
     The circuit arrangement of any of examples 73-80, wherein the driver circuit includes an analog-to-digital converter to perform the one or more voltage measurements. 
     Various aspects have been described in this disclosure. These and other aspects are within the scope of the following claims.