Patent Publication Number: US-2022239090-A1

Title: Parameter threshold level based on signal from controller

Description:
TECHNICAL FIELD 
     This disclosure relates to power electronics. 
     BACKGROUND 
     A power switch manages the flow of electricity from a power supply to a load. Electrical power flows from the power supply to the load when the power switch is activated by a microcontroller. If the current, voltage, or temperature of the power switch exceeds a safety threshold, the power switch may be damaged. To prevent damage, a logic circuit onboard the power switch device or a logic circuit onboard a gate driver device can monitor these parameters and deactivate its output(s) when one or more of the parameters exceeds a respective safety threshold. The microcontroller will receive a shutdown flag from the power switch, but the microcontroller cannot analyze the reason behind that shutdown flag for learning or even for anticipating the next failure. 
     SUMMARY 
     This disclosure describes techniques for setting a pre-warning threshold level for a parameter of a power switch based on a signal sent from a controller to a logic circuit in the power switch device or in a gate driver device. The logic circuit can apply the pre-warning threshold, as well as apply a shutdown level for deactivating the power switch. The logic circuit may be configured to also set the pre-warning threshold level based on the signal received from the controller. The logic circuit is also configured to monitor parameter values of the power switch, where the parameters may include current, voltage, and/or temperature. 
     The techniques of this disclosure may allow for reduced data flow along a communication channel between a controller and a logic circuit in a power switch device or in a gate driver device. The controller may be able to monitor and control numerous devices where each device communicates only alerts to the controller, rather than continuously transmitting parameter values to the controller. 
     In some examples, a device includes memory configured to store a pre-warning threshold level for a parameter of a power switch. The device also includes a logic circuit configured to receive a signal from a controller and set the pre-warning threshold level in response to receiving the signal from the controller. The logic circuit is also configured to determine that a magnitude of the parameter of the power switch does not satisfy the pre-warning threshold level. The logic circuit is further configured to output an alert to the controller in response to determining that the magnitude of the parameter does not satisfy the pre-warning threshold level. 
     In some examples, a method includes storing, by a logic circuit to a memory, a pre-warning threshold level for a parameter of a power switch. The method also includes receiving, by the logic circuit, a signal from a controller and setting, by the logic circuit, the pre-warning threshold level in response to receiving the signal from the controller. The method further includes determining, by the logic circuit, that a magnitude of the parameter of the power switch does not satisfy the pre-warning threshold level. The method includes outputting, by the logic circuit, an alert to the controller in response to determining that the magnitude of the parameter does not satisfy the pre-warning threshold level. 
     In some examples, a system including a power device configured to control a power switch, the power device including a logic circuit and a memory configured to store a pre-warning threshold level for a parameter of the power switch. The system also includes a microcontroller configured to transmit a signal to the power device instructing the logic circuit to set the pre-warning threshold level. The logic circuit is configured to set the pre-warning threshold level in response to receiving the signal from the microcontroller. The logic circuit is also configured to determine that a magnitude of the parameter of the power switch does not satisfy the pre-warning threshold level. The logic circuit is further configured to output an alert to the microcontroller in response to determining that the magnitude of the parameter does not satisfy the pre-warning threshold level. 
     The details of one or more 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 conceptual block diagram of a system including a power switch device and a controller, in accordance with the techniques of this disclosure. 
         FIG. 2  is a conceptual block diagram of a power switch device including a switch, a logic circuit, and memory, in accordance with the techniques of this disclosure. 
         FIG. 3  is a conceptual block diagram of a system including a gate driver device configured to control a power switch, in accordance with the techniques of this disclosure. 
         FIG. 4  is a conceptual diagram of threshold levels for three example parameters of a power switch, in accordance with the techniques of this disclosure. 
         FIGS. 5A-7B  are diagrams of sensed parameters for vehicle fleets, in accordance with the techniques of this disclosure. 
         FIG. 8  is a flow diagram illustrating example techniques for setting a pre-warning threshold level in response to receiving a signal from a controller, in accordance with the techniques of this disclosure. 
         FIG. 9  is a flow diagram illustrating example techniques for instructing a power switch device or a gate driver device to set a pre-warning threshold level for a parameter of a power switch, in accordance with the techniques of this disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     This disclosure describes devices, methods, and techniques for locally monitoring several power devices parameters to ensure that the parameters stay within an acceptable range. A power switch device or a gate driver device can monitor whether each parameter satisfies a respective pre-warning threshold. In response to determining that a parameter does not satisfy a respective pre-warning threshold level, the device may be configured to output an alert to a controller. In some examples, the device may be configured to refrain from outputting the alert in response to determining that the parameter satisfies the respective pre-warning threshold level. 
       FIG. 1  is a conceptual block diagram of a system  102  including a power switch device  100  and a controller  150 , in accordance with the techniques of this disclosure. System  102  includes device  100 , controller  150 , power supply  170 , load  180 , and external network  190 . Although not shown in  FIG. 1 , system  102  may also include additional components such as a gate driver and/or one or more printed circuit boards (PCBs), where device  100  and controller  150  may be mounted to the same PCB or different PCBs. 
     Device  100  includes switch  110 , logic  120 , sensing circuit  130 , and memory  140  in the example shown in  FIG. 1 . Device  100  may also include a gate driver connected between switch  110  and logic  120 , where the gate driver is configured to amplify control signals generated by logic  120  and deliver the amplified signals to switch  110 . Device  100  may include a housing that at least partially encloses switch  110 , logic  120 , sensing circuit  130 , memory  140 , and/or a gate driver. In some examples, device  100  includes a single semiconductor die, where switch  110 , logic  120 , sensing circuit  130 , memory  140 , and/or a gate driver are integrated on the single semiconductor die. Even if switch  110 , logic  120 , sensing circuit  130 , memory  140 , and/or gate driver are integrated on more than one semiconductor die, switch  110 , logic  120 , sensing circuit  130 , memory  140 , and/or a gate driver may be integrated into a single package. 
     Other arrangements are possible including a single package, a single housing, and/or a single semiconductor die including a gate driver and logic  120 , where switch  110  is external to the single package, single housing, or single semiconductor die. Memory  140  may be integrated into the single package, single housing, or single semiconductor die, or memory  140  may be external to and interfaced with the single package, single housing, or single semiconductor die. 
     Switch  110  may be configured to deliver power from power supply  170  to load  180 . In examples in which switch  110  is connected as a high-side switch, switch  110  can deliver power to load  180  when switch  110  is activated and can block the flow of power when switch  110  is deactivated. When switch  110  is activated, load  180  may be electrically connected to power supply  170  through switch  110 . 
     Switch  110  may include, but is not limited to, any type of field-effect transistor (FET) such as a diffusion metal-oxide-semiconductor FET (MOSFET), a bipolar junction transistor (BJT), an insulated-gate bipolar transistor (IGBT), a high-electron-mobility transistor (HEMT), and/or another element that uses voltage for its control. Switch  110  may include n-type transistors and/or p-type transistors. Switch  110  may include semiconductor material such as silicon, silicon carbide, and/or gallium nitride. In some examples, switch  110  may include a plurality of transistors connected in parallel between power supply  170  and load  180 . 
     Logic  120  may be configured to communicate with controller  150 . For example, logic  120  may be configured to set a pre-warning threshold level in response to a signal received from controller  150 . Logic  120  may be configured to output data to controller  150 , where the data may indicate the condition of switch  110 . Logic  120  can output, to controller  150 , an alert indicating that a signal received from sensing circuit  130  does not satisfy a pre-warning threshold level. The alert may communicate to controller  150  that an operating parameter of switch  110  is nearing a shutdown level. 
     In standard operation, logic  120  may be configured to refrain from communicating parameter values to controller  150 , where the each parameter value indicates a magnitude of a signal outputted by sensing circuit  130 . Logic  120  may be configured to begin communicating parameter values to controller  150  in response to a request received from controller  150 . Additionally or alternatively, logic  120  may be configured to begin communicating values for a parameter of switch  110  to controller  150  after outputting an alert indicating that the parameter does not satisfy a pre-warning threshold level. This configuration may allow controller  150  to conduct in-depth monitoring of the parameter values only when circumstances warrant such monitoring. 
     Sensing circuit  130  may be configured to generate a signal indicating a parameter of switch  110 . In some examples, sensing circuit  130  may include a plurality of sensors, where each sensor is configured to generate a signal indicating a respective parameter of switch  110 . Example parameters include temperature (e.g., absolute temperature or change in temperature), voltage, current (e.g., creepage current or leakage current), mechanical strength, and other parameters. Logic  120  may be configured to monitor the parameters of switch  110  without sending the parameter values off-chip (e.g., to controller), except when controller  150  requests parameter values or after logic  120  outputs an alert to controller  150 . 
     Memory  140  may be configured to store one or more threshold levels for monitoring the parameters of switch  110 . For example, memory  140  may be configured to store one or more pre-warning threshold levels indicating that switch  110  is still within a safe operating range but nearing shutdown levels. Memory  140  may be configured to also store one or more shutdown levels for deactivating switch  110  to prevent damage to switch  110 . In addition, memory  140  may be configured to store one or more maximum device threshold levels that represent that outer limits outside of which the shutdown levels cannot be programmed. 
     Controller  150  may include a microcontroller configured to communicate with device  100 . Controller  150  may include processing circuitry, memory, and/or communication interface. Controller  150  may include a first semiconductor die, and device  100  may include a second semiconductor die, where the first semiconductor die is separate from the second semiconductor die. In some examples, device  100  and controller  150  may be mounted on the same PCB or mounted on different PCBs. 
     Power supply  170  may be configured to deliver power to device  100  and controller  150 . Although  FIG. 1  depicts device  100  and controller  150  as receiving power from the same power supply  170 , device  100  and controller  150  may receive power from different supplies in some examples. Power supply  170  may include an energy storage device such as a battery, mains power, and/or any other power source. In the context of an automotive system, power supply  170  may include a twelve-volt battery and/or a  48 -volt battery. In some examples, system  102  may include a power converter connected between power supply  170  and switch  110 , where the power converter may include a DC/DC step-down converter. 
     Load  180  may include a resistive load, a capacitive load, and/or an inductive load. Examples of inductive loads may include actuators, motors, and pumps used in one or more of heating, air conditioning, water supply, a fan, or other systems that include inductive loads. Examples of capacitive loads may include lighting elements. In yet other examples, load  180  may be a combination of resistive, inductive and capacitive loads. In automotive applications, load  180  may include a braking system, a steering system, an autonomous driving system, and/or a driver-assistance system. 
     An existing controller that receives a shutdown flag from a power switch may not be able to determine the event that precipitated the shutdown. Even if the existing controller is able to determine the event that precipitated the shutdown, the controller may not have received any indication that the switch was approaching shutdown before receiving the shutdown flag. Thus, the existing controller could not have predicted the shutdown or diagnosed the issue before the shutdown. Moreover, the existing controller cannot determine how many other switches have experienced similar issues unless those switches have shutdown. 
     In accordance with the techniques of this disclosure, logic  120  may be configured to output an alert to controller  150  in response to determining that a magnitude of a signal received from sensing circuit  130  does not satisfy a pre-warning threshold level stored in memory  140 . The pre-warning threshold level may be within an operating range of switch  110  such that the signal received from sensing circuit  130  will cross the pre-warning threshold level before reaching a shutdown level. After outputting the alert, logic  120  may be configured to begin sending indications of the parameters of switch  110  to controller  150 , either in response to a request from controller  150  or without needing to receive a request from controller. 
     Logic  120  may be configured to refrain from sending an alert or any parameter values to controller  150  in response to determining that the magnitude of a signal received from sensing circuit  130  satisfies the pre-warning threshold level stored in memory  140 . Logic  120  may not communicate any information about parameter values to controller  150  to reduce the workload of controller  150  because controller  150  may be responsible for numerous devices in system  102 . 
     Controller  150  may be configured to send a signal to device  100  instructing logic  120  to set a pre-warning threshold level. Controller  150  may be configured to send such a signal at startup of system  102  (e.g., when an automobile powers on) because the volatile memory onboard device  100  may erase data when device  100  powers off. Controller  150  may be configured to determine a magnitude for the pre-warning threshold level based on a value stored to a memory onboard controller  150  and/or based on communication from external network  190 . 
     Controller  150  may be configured to request that logic  120  begin sending indications of the parameters of switch  110  to controller  150 . Thus, controller  150  can begin actively monitoring parameter values of switch  110  in response to receiving the alert from device  100 . In addition, controller  150  may be configured to store an indication of the alert received from device  100 . Controller  150  may be configured to also store indications of alerts from other devices in system  102  that are coupled to controller  150 . Controller  150  can forward the alert(s) to external network  190  for data analysis by a fleet manager. Additionally or alternatively, controller  150  may be configured to perform the data analysis on-chip, for example, by changing the threshold levels in response to a threshold level has not been crossed or that a threshold level has been crossed several times. 
     In response to determining a threshold level has not been crossed, controller  150  may be configured to shrink the pre-warning threshold level (e.g., increase a lower threshold or decrease an upper threshold). In response to determining a threshold level has been crossed more than a particular number of times, either by device  100  or by multiple devices in system  102 , controller  150  may be configured to expand the pre-warning threshold level. The determination of whether to shrink or expand a threshold level may be based on the magnitude difference between the pre-warning threshold level and the corresponding shutdown level. For example, controller  150  may be configured to determine whether to shrink an upper temperature pre-warning threshold level based on a magnitude difference between that threshold level and an upper temperature shutdown level. 
     External network  190  may include a cloud network for managing a fleet of systems including system  102 . The fleet manager may receive alerts from multiple systems that each include a respective controller and a respective power device, where each system may be mounted on a vehicle in the fleet. The fleet manager may be able to view and compare the alerts outputted by controllers across the fleet via external network  190 . For example, controller  150  may be configured to receive alerts from devices in system  102  such as device  100  and send the alerts to external network  190 . 
       FIG. 2  is a conceptual block diagram of a power switch device  200  including a switch  210 , a logic  220 , and memory  242  and  246 , in accordance with the techniques of this disclosure. Device  200  also includes sensing circuits  232 ,  234 , and  236  and interfaces  252 ,  254 ,  262 ,  272 , and  282 . Interfaces  252  and  254  may be digital interfaces for communication with a controller, such as serial peripheral interface and/or universal asynchronous receiver-transmitter. 
     Switch  210  may be configured to deliver power from interface  272  to interface  282  depending on whether switch  210  is activated or deactivated. Switch  210  can activate or deactivate based on a control signal received from logic  220 . Although not shown in  FIG. 2 , device  200  may include a gate driver connected between switch  210  and logic  220 , where the gate driver is configured to amplify the control signals outputted by logic  220  and deliver the amplified signals to a control terminal of switch  210 . 
     Logic  220  may be configured to communicate with an external device such as a controller via interfaces  252  and  254 . For example, logic  220  may receive a signal from a controller via interface  252 , where the signal indicates a new pre-warning threshold level to be stored to volatile memory  242 . Logic  220  may be configured to output an alert or other information to an external device via interface  254 . Logic  220  may be configured to also receive power from interfaces  262  and  272 , where interface  262  may be connected to a reference voltage supply, and interface  272  may be connected to a high-side power supply. 
     Sensing circuits  232 ,  234 ,  236  are configured to sense the current, temperature, and voltage of switch  210 , respectively. Current sensing circuit  232  may be configured to sense the current conducted by switch  210  from interface  272  to interface  282 . Temperature sensing circuit  234  may be configured to sense the temperature of switch  210 . Voltage sensing circuit  236  may be configured to sense the voltage across switch  210  (e.g., the voltage difference between interfaces  272  and  282 ). 
     In some examples, device  200  only includes one or two of sensing circuits  232 ,  234 ,  236  (e.g., only sensing circuits  232  and  234 ). In some examples, device  200  includes additional sensing circuits not shown in  FIG. 2 . For example, device  200  may include a circuit for sensing electromagnetic energy generated by switch  210 . Current sensing circuits  232  and  236  may include a current mirror, a shunt resistor, a magnetic sensor, and/or any other current or voltage sensor. Temperature sensing circuit  234  may include a temperature-dependent circuit element (such as a temperature-dependent resistor, bipolar junction transistor, diode or other circuit element that operates with temperature dependence), an analog-to-digital converter, a bandgap reference sensor, negative temperature coefficient element, and/or any other type of temperature sensor. 
     Volatile memory  242  may be configured to store pre-warning threshold level(s)  244 . For example, pre-warning thresholds level  244  may include an upper threshold level and/or a lower threshold level for a parameter such as temperature, current, or voltage. In some examples, there may be six pre-warning thresholds level  244  stored to volatile memory  242  (e.g., an upper and a lower threshold level for each of three parameters). In response to determining that a parameter value satisfies the upper and lower threshold levels, logic  220  may be configured to refrain from generating an alert. 
     Non-volatile memory  246  may be configured to store shutdown level(s)  248 . For example, shutdown levels  248  for temperature may include an upper shutdown level and/or a lower shutdown level. In some examples, there may be six shutdown levels  248  stored to non-volatile memory  246  (e.g., an upper and a lower threshold level for each of three parameters). In response to determining that a parameter value does not satisfy shutdown level  248 , logic  220  may be configured to deactivate switch  210 . Non-volatile memory  246  may include memory that can be programmed multiple times because it may be desirable to change the value of shutdown level(s)  248 . Logic  220  may be configured to set a shutdown level based on a command received from a controller via interface  252 . 
     Non-volatile memory  246  may be configured to also store device rating threshold levels that are predefined and/or fixed throughout the lifetime of device  200 . The device rating threshold levels may represent the minimum or maximum parameter values that switch  210  can withstand, as determined by the manufacturer. In some examples, logic  220  cannot change the device rating threshold levels stored to non-volatile memory  246 . Logic  220  may be configured to deactivate switch  210  in response to determining that a parameter value does not satisfy a device rating threshold level. 
       FIG. 3  is a conceptual block diagram of a system including a gate driver device configured to control a power switch, in accordance with the techniques of this disclosure. Logic  320  may be configured to perform any of the techniques described with respect to logic  120  and  220  shown in  FIGS. 1 and 2 . For example, logic  320  may be configured to store a pre-warning threshold level to memory  340  based on a signal received from microcontroller  350 . Logic  320  may be configured to also output an alert to microcontroller  350  in response to determining that a magnitude of a parameter of switch  310  does not satisfy the pre-warning threshold level. 
     Logic  320  may be configured to generate and deliver control signals to gate driver  322 . Gate driver  322  can amplify the control signals received from logic  320  and deliver the amplified signals to the control terminal of switch  310  to activate or deactivate switch  310 . In the example shown in  FIG. 3 , switch  310  is external to device  300 , but an integrated device including a switch, a gate driver, and a logic circuit could also be configured to perform the techniques of this disclosure. 
     In some examples, logic  320 , gate driver  322 , sensing circuit  330 , and memory  340  may be at least partially enclosed by a single housing. Additionally or alternatively, logic  320 , gate driver  322 , sensing circuit  330 , and memory  340  may be integrated on a single semiconductor die. Logic  320 , gate driver  322 , sensing circuit  330 , and memory  340  may be integrated into a single package. 
       FIG. 4  is a conceptual diagram of threshold levels for three example parameters of a power switch, in accordance with the techniques of this disclosure. Although  FIG. 4  depicts upper and lower threshold levels for each parameter for each of cubes  444 ,  448 , and  450 , there may be a single threshold level for a parameter in some examples. Outermost cube  450  represents a device rating for each parameter, which may be fixed throughout the lifetime of a power switch. For example, the logic circuit may be configured to deactivate the power switch when a parameter does not satisfy the limits of outermost cube  450  regardless of the threshold levels stored in memory. 
     Middle cube  448  illustrated by the thick dotted line represents the shutdown levels for each parameter. For example, the logic circuit may be configured to deactivate the power switch when a parameter does not satisfy the shutdown levels. The shutdown levels are stored in non-volatile memory, but the logic circuit may be configured to set or adjust the shutdown levels based on a signal received from a controller. 
     Inner cube  444  illustrated by the thick solid line represents the pre-warning threshold levels for each parameter. For example, the logic circuit may be configured to output an alert when a parameter does not satisfy the pre-warning threshold levels. The pre-warning threshold levels are stored in volatile memory, and the logic circuit may be configured to set the pre-warning threshold levels based on a signal received from a controller. The logic circuit may be configured to set the pre-warning threshold levels after each power cycle because the volatile memory does not store the pre-warning threshold levels when the power is off. 
     Each set of upper and lower threshold levels can form an acceptable range for parameter values. For example, an acceptable pre-warning range for temperature may be between a lower threshold (e.g., zero degrees Celsius) and an upper threshold (e.g., seventy degrees Celsius). The device may be configured to generate an alert in response to determining that the temperature of the switch is outside of the acceptable pre-warning range. The shutdown range for temperature may be more extensive than the acceptable pre-warning range (e.g., negative ten degrees to eighty degrees Celsius). There may also be a threshold level for the change in temperature over time and/or a threshold level for the temperature differential between two locations on the device. A temperature differential between two locations on the device may result in mechanical stress caused by different thermal expansion at the two locations. Thus, there may be a threshold level of five, ten, fifteen, twenty, or thirty Kelvin for the differential between the temperature sensed at two points on the device. 
     A fleet manager may be able to command devices and/or controllers in the fleet to set or change threshold levels for cubes  444  and  448  by sending instruction(s) through an external network. The shutdown levels for cube  448  may be set at the time of manufacture, but the fleet manager or controller may be able to change the shutdown levels during operation of the device. 
       FIGS. 5A-7B  are diagrams of sensed parameters for vehicle fleets, in accordance with the techniques of this disclosure. In the example shown in  FIG. 5A , none of the vehicles have generated an alert due to pre-warning threshold level  500 A or  510 A being crossed. In response to determining that no alerts have been generated or that the number of alerts is smaller than a threshold number, a fleet manager can shrink or constrict the range associated with pre-warning threshold levels  500 B and  510 B for the three parameters, as shown in  FIG. 5B . The fleet manager can decrease the upper temperature pre-warning threshold  510 B away from the upper temperature shutdown level  530 B. Similarly, the fleet manager can increase the upper temperature pre-warning threshold level  500 B away from the lower temperature shutdown level  520 B. The fleet manager may be able to set a threshold level for multiple devices in a system by sending a single command or a copy of the same command to each device in the system. 
     Additionally or alternatively, a controller in one of the fleet systems may be configured to shrink or constrict a pre-warning threshold range in response to determining that the controller has not received an alert from any of the devices that are coupled to the controller, even if the controller has not received any command from the fleet manager. The controller may be configured to shrink (e.g., reduce or decrease) the pre-warning threshold range in response to determining that a predetermined time duration has elapsed without receiving any alerts from the devices. 
     The working area for the three parameters is defined by the pre-warning threshold levels  500 A and  510 A shown in  FIG. 5A . This working area may be overdesigned relative to the actual fleet performance because no information is sent back to the fleet manager in the form of alerts generated due to breached thresholds. Pre-warning threshold levels  500 B and  510 B shown in  FIG. 5B  may be optimized relative to the pre-warning threshold levels shown in  FIG. 5A  because there is a greater likelihood that a device in the fleet may cross pre-warning threshold level  500 B or  510 B, which results in the fleet manager receiving information about the performance of the fleet. The fleet manager can readjust pre-warning threshold levels for better margin evaluation because none of the devices in the fleet shown in  FIG. 5A  generated an alert. 
     In the example shown in  FIG. 6A , a small percentage of the vehicles have generated an alert due to the temperature having breached pre-warning threshold level  610 A. In response to determining that temperature alerts have been generated or that the number of temperature alerts is greater than a threshold number, a fleet manager can expand the pre-warning threshold that has been crossed (e.g., upper temperature threshold level  610 B), as shown in  FIG. 6B . If the number of alerts is less than a threshold number, it may indicate that one or two devices have a soldering problem, rather than a fleetwide issue. The fleet manager can expand the upper temperature pre-warning threshold level  610 B towards the upper temperature shutdown level  630 B, but upper temperature pre-warning threshold level  610 B is still less than the upper temperature shutdown level  630 B. The fleet manager may not change the other five pre-warning threshold levels in examples in which only pre-warning threshold level  610 A has been crossed. 
     The temperature working area shown in  FIG. 6A  may have been designed for regular temperature operating conditions. However, the working area should be expanded for operations in some regions. For example, a fleet of vehicles in Saudi Arabia will likely experience higher operating temperatures, as compared to a fleet of vehicles in Germany or Great Britain. Thus, the working area should be expanded for hot climates by increasing the magnitude of upper temperature pre-warning threshold level  610 A. 
     In the example shown in  FIG. 7A , a percentage of the vehicles have generated an alert due to temperature crossing pre-warning threshold level  710 A, where the percentage of alerting vehicles in  FIG. 7A  is larger than the percentage of alerting vehicles in  FIG. 6A . In response to receiving temperature alerts or determining that the number of temperature alerts is greater than a threshold number, a fleet manager can expand the pre-warning threshold level that has been crossed (e.g., the upper temperature threshold level  710 A), as shown in  FIG. 7B .  FIG. 7B  shows that the fleet manager may increase the upper temperature threshold level by a plurality of increments  712 B. Additionally or alternatively, the fleet manager may cause each device in the fleet to implement a plurality of upper threshold pre-warning threshold levels. Incremental threshold levels may allow for better margin analysis of the extent that each parameter value is exceeding the pre-warning threshold level. 
     Returning to  FIG. 1 , a fleet manager can receive data indicating the number and type of alerts generated by the devices in a fleet from controller  150  and other controllers via external network  190 . Based on an analysis of the alert data, a fleet manager can change a pre-warning threshold level by transmitting an indication of the new threshold level to controller  150  via external network  190 . Thus, the fleet manager and command controller  150  to shrink or expand the boundaries one or more of cubes  444  and  448 . 
     In some examples, the boundaries of cube  450  may be static and predefined because the boundaries of cube  450  represent the device rating (e.g., the maximum threshold levels for parameters of switch  110 ). If a boundary of cube  444  or  448  extends beyond a boundary of cube  450 , logic  120  may be configured to deactivate switch  110  when a parameter value reaches the boundary of cube  450  before reaching the respective boundary of cube  444  or  448 . Thus, controller  150  may be configured to deactivate switch  110  before the parameter value can reach a boundary of cube  444  or  448  that extends beyond a boundary of cube  450 . 
       FIG. 8  is a flow diagram illustrating example techniques for setting a pre-warning threshold level in response to receiving a signal from a controller, in accordance with the techniques of this disclosure. Device  200  shown in  FIG. 2  will be described as performing the techniques of the example shown in  FIG. 8 , but other components, devices, and systems (e.g., device  100 ) may perform similar functionality in other examples. 
     In the example of  FIG. 8 , logic  220  stores pre-warning threshold level  244  for a parameter of switch  210  to volatile memory  242  ( 800 ). Logic  220  then receives a signal from a controller via interface  252  ( 802 ). The signal received via interface  252  may indicate a new value for pre-warning threshold level  244 . Logic  220  sets a new value for pre-warning threshold level  244  in response to receiving the signal from the controller ( 804 ). The previous value for pre-warning threshold level  244  may have been erased during a power cycle, or logic  220  may overwrite the previous value for pre-warning threshold level  244  during operation. 
     Logic  220  determines that a magnitude of the parameter of switch  210  does not satisfy pre-warning threshold level  244  ( 806 ). For example, logic  220  can make this determination by determining that a magnitude of a signal received from one of sensing circuits  232 ,  234 , and  236  is greater than an upper threshold level or is less than a lower threshold level. Likewise, logic  220  may be configured to determine that a parameter value satisfies a threshold level by determining that the parameter value is within an acceptable range. Logic  220  may be configured to determine that a parameter value satisfies a threshold level by determining that the parameter value is greater than a lower threshold level and/or less than an upper threshold level. 
     Logic  220  outputs an alert to the controller via interface  254  in response to determining that the magnitude of the parameter does not satisfy pre-warning threshold level  244  ( 808 ). The alert may include a flag and/or one or more bits that are transmitted by device  200  to the controller. The alert may also include data indicating the time at which logic  220  determined that the parameter value did not satisfy pre-warning threshold level  244 . The alert data can also indicate the magnitude of the parameter value and the threshold level that was crossed. 
     Logic  220  may be configured to generate an alert for each threshold level crossed by a parameter value. For example, logic  220  may be configured to generate a first alert in response to determining that a magnitude of an electrical current through switch  210  does not satisfy a current pre-warning threshold level. Logic  220  may be configured to generate a second alert in response to determining that a magnitude of a temperature of switch  210  does not satisfy a temperature pre-warning threshold level. Logic  220  may be configured to generate a third alert in response to determining that a magnitude of a voltage across switch  210  does not satisfy a voltage pre-warning threshold level. 
       FIG. 9  is a flow diagram illustrating example techniques for instructing a device to set a pre-warning threshold level for a parameter of a power switch, in accordance with the techniques of this disclosure. Controller  150  shown in  FIG. 1  will be described as performing the techniques of the example shown in  FIG. 9 , but other components, devices, and systems (e.g., device  100 ) may perform similar functionality in other examples. 
     In the example shown in  FIG. 9 , controller  150  transmits a signal to device  100  instructing device  100  to set a pre-warning threshold level for a parameter of device  100  ( 900 ). Controller  150  may be configured to transmit a digital signal indicating a magnitude for one or more of the pre-warning threshold levels to device  100 . By sending the pre-warning threshold signal to device  100 , controller  150  can off-load at least some of the responsibility for monitoring the parameters of switch  110 , so that controller  150  does not have to continuously check the parameter values of every device that is coupled to controller  150 . Controller  150  can determine the magnitude of each threshold level based on a predefined value and/or based on communication from external network  190 . In some examples, controller  150  may be configured to determine a magnitude of the pre-warning threshold level based on user input. 
     Controller  150  then receives an alert from device  100  indicating that a parameter of device  100  does not satisfy the pre-warning threshold level ( 902 ). Controller  150  may also receive the magnitude of the parameter value that crossed a threshold level from device  100 . Controller  150  can store the alert and, in some examples, send a command to device  100  to begin reporting parameter values to controller  150 . For example, device  100  may begin transmitting values for the parameter that crossed the threshold level back to controller  150  after transmitting the alert to device  100 . 
     In response to determining that an alert has not been received from device  100 , controller  150  may be configured to determine that the parameter values of switch  110  satisfy the respective pre-warning threshold levels. In other words, in response to determining that an alert has not been received from device  100 , controller  150  may be configured to determine the pre-warning threshold levels have not been crossed. 
     In the example of  FIG. 9 , controller  150  transmits an indication of the alert to external network  190  ( 904 ). Controller  150  may be configured to send data to external network  190 , where the data can indicate the number and type of alerts received by controller  150  from multiple devices in system  102 . In some examples, controller  150  is configured to send commands to and receive alerts from multiple devices including device  100 . In addition, controller  150  can store data indicating the alerts received from the devices. Each device in system  102  may include a respective switch and a respective memory for storing threshold levels for parameters of the switch. 
     This disclosure has attributed functionality to devices  100  and  200 , logic  120  and  220 , memory  140 ,  242 , and  246 , and distribution circuits  310 ,  314 ,  316 , and  318 . Devices  100  and  200 , logic  120  and  220 , memory  140 ,  242 , and  246 , and distribution circuits  310 ,  314 ,  316 , and  318  may include processing circuitry such as one or more processors. Devices  100  and  200 , logic  120  and  220 , memory  140 ,  242 , and  246 , and distribution circuits  310 ,  314 ,  316 , and  318  may include any combination of integrated circuitry, discrete logic circuity, analog circuitry, such as one or more microprocessors, digital signal processors (DSPs), application specific integrated circuits (ASICs), and/or field-programmable gate arrays (FPGAs). In some examples, devices  100  and  200 , logic  120  and  220 , memory  140 ,  242 , and  246 , and distribution circuits  310 ,  314 ,  316 , and  318  may include multiple components, such as any combination of one or more microprocessors, one or more DSPs, one or more ASICs, or one or more FPGAs, as well as other discrete or integrated logic circuitry, and/or analog circuitry. 
     The techniques described in this disclosure may also be encoded in instructions and data stored to a non-transitory computer-readable storage medium, such as memory  140 , 242 , and  246 . Example non-transitory computer-readable storage media may include RAM, ROM, programmable ROM (PROM), erasable programmable ROM (EPROM), electronically erasable programmable ROM (EEPROM), flash memory, a hard disk, magnetic media, optical media, or any other computer readable storage devices or tangible computer readable media. The term “non-transitory” may indicate that the storage medium is not embodied in a carrier wave or a propagated signal. In certain examples, a non-transitory storage medium may store data that can, over time, change (e.g., in RAM or cache). 
     The following numbered examples demonstrate one or more aspects of the disclosure. 
     Example 1. A method includes storing, by a logic circuit to a memory, a pre-warning threshold level for a parameter of a power switch. The method also includes receiving, by the logic circuit, a signal from a controller and setting, by the logic circuit, the pre-warning threshold level in response to receiving the signal from the controller. The method further includes determining, by the logic circuit, that a magnitude of the parameter of the power switch does not satisfy the pre-warning threshold level. The method includes outputting, by the logic circuit, an alert to the controller in response to determining that the magnitude of the parameter does not satisfy the pre-warning threshold level. 
     Example 2. The method of example 1, further including storing a shutdown level to a non-volatile memory. 
     Example 3. The method of example 1 or example 2, further including determining that the parameter does not satisfy a shutdown level. 
     Example 4. The method of examples 1-3 or any combination thereof, further including deactivating the power switch in response to determining that the parameter does not satisfy a shutdown level. 
     Example 5. The method of examples 1-4 or any combination thereof, further including setting a shutdown level in response to receiving a second signal from the controller. 
     Example 6. The method of examples 1-5 or any combination thereof, wherein storing the pre-warning threshold level includes storing the pre-warning threshold level to a volatile memory. 
     Example 7. The method of examples 1-6 or any combination thereof, wherein the parameter comprises a current through the power switch. 
     Example 8. The method of examples 1-7 or any combination thereof, wherein the parameter comprises a voltage across the power switch. 
     Example 9. The method of examples 1-8 or any combination thereof, wherein the parameter comprises a temperature of the power switch. 
     Example 10. The method of examples 1-9 or any combination thereof, further including outputting the magnitude of the parameter of the power switch to the controller in response to determining that the magnitude of the parameter of the power switch does not satisfy the pre-warning threshold level. 
     Example 11. The method of examples 1-10 or any combination thereof, further including determining, in a second instance, that the magnitude of the parameter of the power switch satisfies the pre-warning threshold level. 
     Example 12. The method of examples 1-11 or any combination thereof, further including not outputting the magnitude of the parameter of the power switch to the controller in response to determining that the magnitude of the parameter of the power switch satisfies the pre-warning threshold level. 
     Example 13. The method of examples 1-12 or any combination thereof, further including refraining from outputting the alert to the controller in response to determining that the magnitude of the parameter satisfies the pre-warning threshold level. 
     Example 14. The method of examples 1-13 or any combination thereof, further including setting a second pre-warning threshold level for a second parameter in response to receiving a second signal from the controller. 
     Example 15. The method of examples 1-14 or any combination thereof, further including outputting a second alert to the controller in response to determining that a magnitude of a second parameter does not satisfy a second pre-warning threshold level. 
     Example 16. The method of examples 1-15 or any combination thereof, further including setting a third pre-warning threshold level for a third parameter in response to receiving a third signal from the controller. 
     Example 17. The method of examples 1-16 or any combination thereof, further including outputting a third alert to the controller in response to determining that a magnitude of a third parameter does not satisfy a third pre-warning threshold level. 
     Example 18. The method of examples 1-17 or any combination thereof, wherein determining that the magnitude of the parameter of the power switch does not satisfy the pre-warning threshold level includes determining that a magnitude of a signal received from a sensing circuit or from a sensor does not satisfy the pre-warning threshold level. 
     Example 19. The method of examples 1-18 or any combination thereof, further including storing lower and upper pre-warning threshold levels to the memory. 
     Example 20. The method of examples 1-19 or any combination thereof, further including determine that the magnitude of the parameter of the power switch satisfies the pre-warning threshold levels by determining that the magnitude of the parameter is greater than or equal to the lower pre-warning threshold level and is less than or equal to the upper pre-warning threshold level. 
     Example 21. The method of examples 1-20 or any combination thereof, further including storing an updated value of the pre-warning threshold level in response to receiving an updated signal from the controller. 
     Example 22. The method of examples 1-21 or any combination thereof, further including activating the power switch to cause the power switch to connect a power supply to a load. 
     Example 23. A device including a memory configured to store a pre-warning threshold level for a parameter of a power switch. The device also includes a logic circuit configured to perform the method of examples 1-22 or any combination thereof 
     Example 24. A device includes and memory configured to store a pre-warning threshold level for a parameter of the power switch. The device also includes a logic circuit configured to receive a signal from a controller and set the pre-warning threshold level in response to receiving the signal from the controller. The logic circuit is also configured to determine that a magnitude of the parameter of the power switch does not satisfy the pre-warning threshold level. The logic circuit is further configured to output an alert to the controller in response to determining that the magnitude of the parameter does not satisfy the pre-warning threshold level. 
     Example 25. The device of example 23 or example 24, further including the power switch as part of the device. 
     Example 26. The device of examples 23-25 or any combination thereof, wherein the power switch is separate from the device. 
     Example 27. The device of examples 23-26 or any combination thereof, further including a gate driver configured to activate the power switch based on control signals received from the logic circuit. 
     Example 28. The device of examples 23-27 or any combination thereof, further including a non-volatile memory configured to store a shutdown level. 
     Example 29. The device of examples 23-28 or any combination thereof, further including a volatile memory configured to store the pre-warning threshold level for the parameter of the power switch. 
     Example 30. The device of examples 23-29 or any combination thereof, further including a single housing at least partially enclosing the power switch, the memory, and the logic circuit. 
     Example 31. The device of examples 23-30 or any combination thereof, further including a single housing at least partially enclosing a gate driver, the memory, and the logic circuit. 
     Example 32. The device of examples 23-31 or any combination thereof, further including a single semiconductor die, wherein the power switch, the memory, and the logic circuit are integrated into a single semiconductor die. 
     Example 33. The device of examples 23-32 or any combination thereof, wherein the power switch, the memory, and the logic circuit are integrated into a single package. 
     Example 34. A system including a power device configured to control a power switch. The power device includes a memory configured to store a pre-warning threshold level for a parameter of a power switch. The device also includes a logic circuit configured to perform the method of examples 1-22 or any combination thereof. The system further includes a microcontroller configured to transmit a signal to the power device instructing the logic circuit to set the pre-warning threshold level. 
     Example 35. A system including a power device configured to control a power switch, the power device including a logic circuit and a memory configured to store a pre-warning threshold level for a parameter of the power switch. The system also includes a microcontroller configured to transmit a signal to the power device instructing the logic circuit to set the pre-warning threshold level. The logic circuit is configured to set the pre-warning threshold level in response to receiving the signal from the microcontroller. The logic circuit is also configured to determine that a magnitude of the parameter of the power switch does not satisfy the pre-warning threshold level. The logic circuit is further configured to output an alert to the microcontroller in response to determining that the magnitude of the parameter does not satisfy the pre-warning threshold level. 
     Example 36. The system of examples 34-35 or any combination thereof, further including a PCB, where the power device and the microcontroller are mounted on the PCB. 
     Example 37. The system of examples 34-36 or any combination thereof, wherein the microcontroller is configured to instruct the logic circuit to reduce the pre-warning threshold level in response to determining that the microcontroller has not received the alert from the power device. 
     Example 38. The system of examples 34-37 or any combination thereof, further including a plurality of power devices, wherein the microcontroller is configured to transmit a respective signal to each respective power device instructing the respective power device to set a respective pre-warning threshold level for the parameter of the respective power device. 
     Example 39. The system of examples 34-38 or any combination thereof, wherein the microcontroller is configured to transmit, in response to receiving the alert, a second signal indicating the alert to an external network for comparison of multiple systems that each include a respective microcontroller and a respective power device. 
     Example 40. The system of examples 34-39 or any combination thereof, wherein the microcontroller is configured to receive a third signal from an external network, the third signal including an instruction to set the pre-warning threshold level to a new value. 
     Example 41. The system of examples 34-40 or any combination thereof, wherein the microcontroller configured to transmit, in response to receiving a third signal from an external network, a fourth signal to the power device instructing the logic circuit to set the pre-warning threshold level to a new value. 
     Example 42. The system of examples 34-41 or any combination thereof, wherein the new value is determined based on analysis of data received by the external network from a fleet of vehicles including a first vehicle, wherein the system is configured to be installed on the first vehicle. 
     Example 43. A device includes a computer-readable medium having executable instructions stored thereon, configured to be executable by processing circuitry for causing the processing circuitry to perform the method of examples 1-22 or any combination thereof. 
     Example 44. A system includes means for performing the method of examples 1-22 or any combination thereof. 
     Various examples of the disclosure have been described. Any combination of the described systems, operations, or functions is contemplated. These and other examples are within the scope of the following claims.