Patent ID: 12218597

The foregoing and other objects, features, and advantages of embodiments herein will be apparent from the following more particular description herein, as illustrated in the accompanying drawings in which like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, with emphasis instead being placed upon illustrating the embodiments, principles, concepts, etc.

DETAILED DESCRIPTION

Embodiments herein include implementation of body diode cross conduction protection in a voltage converter in any number of multiple different ways.

Now, more specifically,FIG.1is an example diagram illustrating a power supply according to embodiments herein.

As shown in this example embodiment, power supply100(such as an apparatus, electronic device, resonant power converter, etc.) includes a controller140and voltage converter110. Voltage converter110(such as a resonant power converter) includes switch121, switch122, transformer160, etc. Transformer160includes primary winding161and secondary winding162.

Primary stage151of the voltage converter110includes switch121, switch122, as well as primary winding161. Secondary stage152includes secondary winding162and corresponding circuitry to generate the output voltage123that powers the load118.

Note that each of the resources as described herein can be instantiated in any suitable manner. For example, each of the controller140and voltage converter110, etc., in power supply100can be instantiated as or include hardware (such as circuitry), software (executed instructions), or a combination of hardware and software resources.

During operation, controller110produces one or more control signals105(such as one or more pulse width modulation signals) that control states of respective control switches121and122in the voltage converter110to produce the output voltage123.

Note that switches121and122can be any suitable type of components. For example, each of the switches121and122may be a field effect transistor, bipolar junction transistor, etc.

As further shown, the voltage converter110receives the input voltage120(Vin, such as a DC input voltage). As previously discussed, transformer160includes a primary winding161and a secondary winding162. The secondary winding162is inductively or magnetically coupled to the primary winding161to receive energy provided by the input voltage120. For example, control of current through the primary winding161stores energy in the primary winding161. The stored energy transfers from the primary winding161to the secondary winding162to produce the output voltage123.

As further discussed herein, controller140of the power supply100controllably switches the switches121and122in a respective circuit path including the primary winding161of transformer160to convey energy to the secondary winding152. Switches121and122may be connected in series. The switching of switches121and122causes a change in a magnitude of current flowing through the primary winding. The secondary stage152of the voltage converter110converts the received energy from the primary winding161into the output voltage123that powers the load118.

In accordance with further embodiments, voltage converter110generates signal Vhb (a.k.a., voltage VHb). As further discussed herein, the controller140uses the detected state of signal Vhb to control operation of the switches.

As previously discussed, during switching operation, the secondary winding162is operable to receive energy from the primary winding161to produce the output voltage123to power the load123. For example, the controller140controls switching operation of the first switch121and the second switch122to control a flow of current through the primary winding161to generate the output voltage123from the secondary winding162.

Note that the voltage converter110as described herein is any suitable type of power supply or power converter. For example, in one embodiment, the voltage converter110takes the form of an asymmetrical half bridge flyback voltage converter. Alternatively, the voltage converter110takes the form of a symmetrical half bridge flyback voltage converter. The voltage converter110can be configured in any suitable manner.

FIG.2is a diagram illustrating a controller and a more detailed rendition of an example power supply according to embodiments herein.

In this example embodiment, the switch121is instantiated as a field effect transistor including a body diode D1, a gate (G), drain (D), and source (S). Additionally, the switch122is instantiated as a field effect transistor including a body diode D2, a gate (G), drain (D), and source (S).

Driver241(such as high side switch driver circuitry) of the controller140is electrically connected to the gate of switch121. The drain node of the switch121is connected to receive the input voltage120. At node281, the source node of the switch121is connected to the drain node of switch122. Switch121and switch122are connected in series.

Driver242(such as low side switch driver circuitry) of the controller140is electrically connected to drive the gate of switch122. The source node of switch122is connected to a first ground reference potential291.

As further shown, the body diode D1(inherent or parasitic diode) is disposed between the source node of switch121and the drain node of switch121. The body diode D2is connected between the source node of switch122and the drain node of switch122.

In accordance with further embodiments, the voltage converter110includes a resonant circuit path (combination of inductor L1, primary winding161, and resonant capacitor C1) disposed between the node281and the ground reference potential291. More specifically, the resonant circuit path includes a series connection of inductor L1(optional component) connected between the node281and node282of the primary winding161. The primary winding161is connected in series with the capacitor C1between node282and the ground reference potential291.

The body diode D2(inherent or parasitic diode) of switch122is disposed between the source node of switch122and the drain node of switch122.

As further shown, the secondary winding162is connected between node283and the diode D3. The combination of secondary winding162and diode D3are connected in series between node283and the second ground reference potential292.

Capacitor Cout is connected between node283and the second ground reference potential292.

As previously discussed, the primary winding161of the transformer160is disposed in a resonant circuit path such as the circuit path including a combination of the inductor L1, primary winding161, and the capacitor C1(a.k.a., Cr). The controller140controls a magnitude of the switching frequency associated with the control signals105at or around the resonant frequency associated with the resonant circuit path.

Activation of the switch121to an ON state (while the switch122is set to an OFF state) stores energy received from the input voltage120in the resonant circuit path as well as conveys energy from the primary winding161to the secondary winding162. Activation of the switch122to an ON state (while the switch121is set to an OFF state) dissipates energy stored in the resonant circuit path through the primary winding161to the secondary winding162.

As previously discussed, the node281feeds voltage Vhb (a.k.a., feedback signal Vhb) to the controller140. As further shown, the controller140includes comparator240. In one embodiment, during operation, comparator240compares a magnitude of the feedback signal Vhb to a threshold value TV2. The magnitude of the threshold value TV2can be set to any suitable value such as between a magnitude of the reference voltage291and magnitude of the input voltage120.

Based on the comparison of the feedback voltage signal Vhb to the threshold value TV2(threshold voltage TV2), the comparator240produces a respective trigger signal103, a state of which may depend upon whether the feedback voltage signal Vhb is greater or less than the threshold voltage TV2. Thus, the comparator240detects when the magnitude of the feedback voltage signal Vhb crosses the respective threshold voltage TV2and produces the signal103. Delay timer255receives the trigger signal103, which serves as a basis in which to activate the delay timer255.

As further discussed below (such as inFIGS.3A,3B, and3Cas well), after expiry of a time delay (such as time delay TD1) as measured by timer255with respect to a trigger event as indicated by trigger signal103, the controller140controls the driver241to activate the switch121to an ON-state. In such an instance, upon expiry of the time delay TD1, the timer255outputs control signal104, which provides a basis in which to control timing and generation of control signal105-1at an appropriate time with respect to control signal105-2such that there is no (or substantially no) cross-conduction when switch121is activated to an ON-state. In other words, to prevent cross conduction, as further discussed herein, the controller140prevents activation of switch121until after a condition in which the body diode D2no longer conducts and current no longer flows through the body diode D2. This is further illustrated inFIGS.3A,3B, and3C.

FIGS.3A,3B, and3Care example timing diagrams illustrating implementation of signal monitoring and switch control in a power converter to prevent cross conduction according to embodiments herein.

As previously discussed, the controller140monitors a magnitude of the feedback voltage signal Vhb produced by node281coupling the switch121and switch122. A magnitude of the monitored feedback voltage signal Vhb during the OFF state of the switch122is used as a basis to determine whether current flows through the body diode D2of the second switch122.

In one embodiment, the controller140is further operable to initiate activation of the first switch121after expiration of a predetermined delay amount of time TD1, which corresponds to a condition in which there is no current (such as Ihb) flowing through the body diode D2of the switch122. The predetermined time TD1can be as little as no time or a predetermined amount of time greater than zero.

Note that the magnetizing current Imag represents the energy stored in the inductance of the transformer. Ihb is the current measured at the input of the primary winding of the transformer; in one embodiment, it is composed of the magnetizing current and the reflected current from the other windings (forward currents).

As further shown,FIG.3Bindicates states of control signals105that control switch121and switch.

For example, between time T30and time T31, the controller140controls a state of the driver242and corresponding control signal105-2to a logic high state while driver241drives control signal105-1to a logic low state. In such an instance, the current (Imag) decreases. The magnitude of the current Ihb also decreases. Activation of the switch122between time T30and T31causes the resonant circuit path (such as inductor L1, primary winding161, and capacitor C1) to dissipate energy in the corresponding resonant circuit path to convey energy from primary winding161to the secondary winding162, which is used to generate the output voltage123that powers the load118.

At time T31, the controller140resets the control signal105-2to a logic low resulting in the deactivation of the switch122. The diode D2of switch122conducts at least for a short amount of time after switch122is turned off at time T31. During the dead time when both of the switches121and122are in an OFF-state, after time T31, the comparator240compares the magnitude of the feedback voltage signal Vhb to the threshold level TV2.

In response to detecting at time or around time T32that the magnitude of the feedback voltage signal Vhb (crosses) increases above the threshold voltage level TV2, the comparator240generates the trigger signal103(such as an edge trigger) to indicate the detected condition. Note that after voltage signal Vhb increases to a sufficient level, it is safe to turn on the switch121again because it is known that the current through diode D2is zero or substantially zero. This prevents cross conduction.

As previously discussed, the trigger signal103(indicating that the magnitude of the signal Vhb crosses the threshold voltage TV2) causes the delay timer255to be activated. After expiration of the predetermined time delay TD1measured (by the delay timer255) with respect to time T32, the delay timer255changes a state of the control signal104(such as via falling edge) to indicate that it is time to activate the switch121again. In other words, after expiration of the time delay TD1at time T32, the controller140activates the control signal105-1to a logic high state to activate the switch121.

Thus, time window between time T31and T33represents a dead time in which the controller140sets switches121and122to OFF states (logic low). The controller140uses a magnitude of the feedback signal Vhb as a basis to control switch121. Implementation of the delay TD1with respect to the trigger103(at time T32) ensures that there is no current through the body diode D2at or around time T33when the switch121is activated to an on state again after time TD1. Thus, cross conduction is avoided.

Activation of the switch121(while switch122is OFF) between time duration T33to T34causes an increase in current Ihb through the primary winding161again as shown inFIG.3A. Activation of the switch121between time T33and T34causes the resonant circuit path (inductor L1, primary winding161, and capacitor C1) to store energy as well as convey energy from primary winding161to the secondary winding162, which is used to generate the output voltage123that powers the load118.

Accordingly, the controller140as described herein can be configured to implement a time delay TD1between a time of detecting a condition in which the feedback voltage signal Vhb crosses a respective threshold voltage TV2and activating the switch121to the ON-state to ensure that there is no current flowing through the body diode D2when the switch121is activated to the on state.

Note that the time window between time T34and T35represents a dead time in which the controller140sets switches121and122to OFF states (logic low).

After time T35, in a window between time T35and T36, the control cycle then repeats in which the controller140initially activates the switch122to an ON state at time T35while switch121is turned OFF.

It should be noted that the magnitude of the feedback signal Vhb may not increase above the respective threshold value TV2during a respective control cycle. To accommodate such conditions, and provide proper control, the controller140and corresponding delay timer255can be configured to measure a second time delay TD2after detecting a condition in which the control signal105-2is set to a low state to deactivate the switch122. More specifically, at time T36, the controller deactivates the switch122to an OFF-state while switch121is also set to the OFF-state. In a similar manner as previously discussed, the controller140can be configured to monitor for a condition in which a magnitude of the feedback voltage Vhb crosses the threshold value TV2. This may not happen. For example, this does not happen between time T36and T37.

In response to detecting that the magnitude of the feedback signal Vhb does not increase above the threshold voltage TV2within the time delay TD2, the controller140sets the control signal105-1to the logic high state to turn on the switch121at time T37.

Thus, embodiments herein include operations such as i) activating the switch121to the ON-state after a delay of TD1with respect to detecting that the feedback signal Vhb crosses the threshold value TV2or ii) activating the switch121to the ON-state in response to detecting expiration of a time delay value TD2subsequent to the deactivating the switch122in a control cycle to prevent occurrence of body diode cross conduction (such as switch121in an on state when current flows through diode D2). Note that the controller140can be configured to simultaneously monitor for both of these conditions (such as signal Vhb greater than TV2or the signal Vhb does not threshold value TV2within the time delay TD2. If either condition occurs, the controller140activates the switch121again. More specifically, the controller140detects the condition i between time T31and time T33; the controller140detects the condition ii between time T36and time T37.

FIG.4is an example diagram illustrating a more detailed rendition of a power supply and corresponding controller according to embodiments herein.

In this example embodiment, the switch121is instantiated as a field effect transistor including a body diode D1, a gate (G), drain (D), and source (S). Additionally, the switch122is instantiated as a field effect transistor including a body diode D2, a gate (G), drain (D), and source (S).

Driver241(such as high side switch driver circuitry) of the controller140is electrically connected to the gate of switch121. The drain node of the switch121is connected to receive the input voltage120. At node281, the source node of the switch121is connected to the drain node of switch122. Switch121and switch122are connected in series.

Driver242(such as low side switch driver circuitry) of the controller140is electrically connected to drive the gate of switch122. The source node of switch122is connected to a first ground reference potential291.

As further shown, the body diode D1(inherent or parasitic diode) is disposed between the source node of switch121and the drain node of switch121. The body diode D2is connected between the source node of switch122and the drain node of switch122.

In accordance with further embodiments, the voltage converter110includes a resonant circuit path (combination of inductor L1, primary winding161, and capacitor C1) disposed between the node281and the node284(input voltage120). More specifically, the resonant circuit path includes a series connection of inductor L1(optional) connected between the node281and node282. The primary winding161is connected in series with the capacitor C1between node282and the node284.

The body diode D2(inherent or parasitic diode) of switch122is disposed between the source node of switch122and the drain node of switch122.

As further shown, the secondary winding162is connected between node283and the diode D3. The combination of secondary winding162and diode D3are connected in series between node283and the second ground reference potential292.

Capacitor Cout is connected between node283and the second ground reference potential292.

As previously discussed, the primary winding161of the transformer160is disposed in a resonant circuit path such as the circuit path including a combination of the inductor L1, primary winding161, and the capacitor C1(Cr). The controller140controls a magnitude of the switching frequency associated with the control signals105based upon the resonant frequency associated with the resonant circuit path.

Activation of the switch122to an ON state (while the switch121is set to an OFF state) stores energy received from the input voltage120in the resonant circuit path as well as conveys energy from the primary winding161to the secondary winding162. Activation of the switch121to an ON state (while the switch122is set to an OFF state) dissipates energy stored in the resonant circuit path through the primary winding161to the secondary winding162.

As previously discussed, the node281feeds signal Vhb (such as feedback signal Vhb) to the controller140. As further shown, the controller140includes comparator240. In one embodiment, during operation, comparator240compares a magnitude of the feedback signal Vhb to a threshold value TV4. The magnitude of the threshold value TV4can be set to any suitable value such as between a magnitude of the reference voltage291and magnitude of the input voltage120.

Based on the comparison of the feedback voltage signal Vhb to the threshold value TV4(threshold voltage TV4), the comparator240produces a respective trigger signal103, a state of which depends upon whether the feedback voltage signal Vhb is greater or less than the threshold voltage TV4. Thus, the comparator240detects when the magnitude of the feedback voltage signal Vhb crosses (such as drops below) the respective threshold voltage TV4.

Delay timer255receives the trigger signal103, which serves as a basis in which to activate the delay timer255and measure time.

More specifically, as further discussed below (such as inFIGS.5A,5B, and5Cas well), after expiry of a time delay (such as time delay TD3) as measured by timer255with respect to a trigger event as indicated by trigger signal103, the controller140controls the driver242to activate the switch122to an ON-state subsequent to a time of deactivating the second switch121to an OFF-state. For example, upon expiry of the time delay TD3, the timer255outputs control signal104, which provides a basis in which to control timing and generation of control signal105-2at an appropriate time with respect to control signal105-1such that there is no (or substantially no) cross-conduction when switch122is activated to an ON-state. In other words, to prevent cross conduction, as further discussed herein, the controller140prevents activation of switch122until after a condition in which the body diode D1no longer conducts and current no longer flows through the body diode D1. This is further illustrated inFIGS.5A,5B, and5C.

FIGS.5A,5B, and5Care example timing diagrams illustrating implementation of signal monitoring and switch control in a power converter to prevent cross conduction according to embodiments herein.

As previously discussed, the controller140monitors a magnitude of the feedback voltage signal Vhb produced by node281coupling the switch121and switch122. A magnitude of the monitored feedback voltage signal Vhb during the OFF state of the switch121is used as a basis to determine whether current flows through the body diode D1of the second switch121.

In one embodiment, the controller140is further operable to initiate activation of the first switch121after expiration of a predetermined delay amount of time TD3, which corresponds to a condition in which there is no current (such as Ihb) flowing through the body diode D1of the switch121. The predetermined time TD3can be as little as no time or a predetermined amount of time greater than zero.

As further shown,FIG.5Bindicates states of control signals105that control switch121and switch122.

For example, between time T40and time T41, the controller140controls a state of the driver241and corresponding control signal105-1to a logic high state while driver242drives control signal105-2to a logic low state. In such an instance, the current (Imag) decreases. The magnitude of the current Ihb also decreases.

At time T41, the controller140produces the control signal105-1to a logic low resulting in the deactivation of the switch121. The diode D1of switch121conducts at least for a short amount of time after it is turned off. During the dead time when both of the switches121and122are in an OFF-state, after time T41, the comparator240compares the magnitude of the feedback voltage signal Vhb to the threshold level TV4.

In response to detecting at or around time T42that the magnitude of the feedback voltage signal Vhb decreases below the threshold voltage level TV4, the comparator240generates the trigger signal103(such as an edge trigger) to indicate the detected condition. Note that after voltage signal Vhb decreases to a sufficient level, it is safe to turn on the switch122again because it is known that the current through diode D1zero or substantially zero.

As previously discussed, the trigger signal103(indicating that the magnitude of the signal Vhb crosses the threshold voltage TV4) causes the delay timer255to be activated. After expiration of the predetermined time delay TD3measured (by the delay timer255) with respect to time T42, the delay timer255changes a state of the control signal104(such as via falling edge) to indicate that it is time to activate the switch121again. In other words, after expiration of the time delay TD3at time T43, the controller140activates the control signal105-2to a logic high state to activate the switch122.

Thus, time window between time T41and T43represents a dead time in which the controller140sets switches121and122to OFF states (logic low). The controller140uses a magnitude of the feedback signal Vhb as a basis to control switch122on again. Implementation of the delay TD3with respect to the trigger103(at time T42) ensures that there is no current through the body diode D1at or around time T43when the switch122is activated to an on state again after time TD3. Thus, cross conduction is avoided.

Activation of the switch122(while switch121is OFF) between time duration T43to T44causes an increase in current Ihb through the primary winding161again as shown inFIG.5A.

Accordingly, the controller140as described herein can be configured to implement a time delay TD3between a time of detecting a condition in which the feedback voltage signal Vhb crosses a respective threshold voltage TV4and activating the switch122to the ON-state to ensure that there is no current flowing through the body diode D1when the switch122is activated to the on state.

Note that the time window between time T44and T45represents a dead time in which the controller140sets switches121and122to OFF states (logic low).

After time T45, in a window between time T45and T46, the control cycle then repeats in which the controller140initially activates the switch121to an ON state at time T45while switch122is turned OFF.

It should be noted that the magnitude of the feedback signal Vhb may not decrease below the respective threshold value TV4during a respective control cycle. To accommodate such a condition, the controller140and corresponding delay timer255can be configured to measure a second time delay TD4after detecting a condition in which the control signal105-1is set to a low state to deactivate the switch121. More specifically, at time T46, the controller deactivates the switch121to an OFF-state while switch121is also set to the OFF-state. In a similar manner as previously discussed, the controller140can be configured to monitor for a condition in which a magnitude of the feedback voltage Vhb crosses the threshold value TV4. This may not happen. For example, this does not happen between time T46and T47.

In response to detecting that the magnitude of the feedback signal Vhb does not decrease below the threshold voltage TV4within the time delay TD4measured from time T46, the controller140sets the control signal105-2to the logic high state to turn on the switch122at time T47.

Embodiments herein include operations such as i) activating the switch122to the ON-state after a delay of TD3with respect to detecting that the feedback signal Vhb crosses the threshold value TV4or condition ii) activating the switch122to the ON-state in response to detecting expiration of a time delay value TD4subsequent to the deactivating the switch121in a control cycle. These operations prevent occurrence of body diode cross conduction (such as switch122in an on state when current flows through diode D1). Note that the controller140can be configured to simultaneously monitor for both of these conditions. If either condition i or ii occurs, the controller140activates the switch122again. More specifically, the controller140detects the condition i between time T41and time T43; the controller140detects the condition ii between time T46and time T47to activate the switch122.

FIG.6is an example diagram illustrating a more detailed rendition of a power supply and corresponding controller according to embodiments herein.

In this example of the power supply100(a.k.a., resonant power converter), the power supply100includes controller640, switch121, switch122, inductor L1, transformer160, capacitor C1, resistor R1, diode D3, and capacitor Cout. The transformer660includes primary winding161, secondary winding162, and auxiliary winding163.

Each of the windings in the transformer660is magnetically coupled to each other. For example, the primary winding161, secondary winding162, and the auxiliary winding163are magnetically or inductively coupled to each other.

In this example embodiment of the power supply100, the switch121is instantiated as a field effect transistor including a body diode D1, a gate (G), drain (D), and source (S). Additionally, the switch122is instantiated as a field effect transistor including a body diode D2, a gate (G), drain (D), and source (S).

Driver641(such as high side switch driver circuitry) of the controller640is electrically connected to the gate of switch121. The drain node of the switch121is connected to receive the input voltage120. At node681, the source node of the switch121is connected to the drain node of switch122. Switch121and switch122are connected in series.

Driver642(such as low side switch driver circuitry) of the controller640is electrically connected to drive the gate of switch122. The source node of switch122is connected to a first ground reference potential291.

As further shown, the body diode D1(inherent or parasitic diode) is disposed between the source node of switch121and the drain node of switch121. The body diode D2is connected between the source node of switch122and the drain node of switch122.

In accordance with further embodiments, the voltage converter110includes a resonant circuit path (combination of inductor L1, primary winding161, capacitor C1, and resistor R1) disposed between the node681and the ground reference potential291. More specifically, the resonant circuit path includes a series connection of inductor L1(optional) connected between the node681and node682of the primary winding161. The primary winding161is connected in series with the capacitor C1between node686.

Node684provides coupling between the primary winding161and the capacitor C1. The voltage Vcr at node684is fed back to the controller640.

Node686provides coupling between the resistor R1, the source node of switch122, and capacitor C1. The voltage Vcs at node686is fed back to the controller640.

The auxiliary winding163is connected between node685and the ground reference potential291. The voltage Vzcd is fed back to the controller640.

Note further that the body diode D2(inherent or parasitic diode) of switch122is disposed between the source node of switch122and the drain node of switch122.

As further shown, the secondary winding162is connected between node683and the diode D3. The combination of secondary winding162and diode D3are connected in series between node683and the second ground reference potential292.

Capacitor Cout is connected between node683and the second ground reference potential292.

As previously discussed, the primary winding161of the transformer660is disposed in a resonant circuit path such as the circuit path including a combination of the inductor L1, primary winding161, and the capacitor C1(Cr). The controller640controls a magnitude of the switching frequency associated with the control signals105based upon the resonant frequency associated with the resonant circuit path.

Activation of the switch121to an ON state (while the switch122is set to an OFF state) stores energy received from the input voltage120in the resonant circuit path as well as conveys energy from the primary winding161to the secondary winding162and auxiliary winding163. Activation of the switch122to an ON state (while the switch121is set to an OFF state) dissipates energy stored in the resonant circuit path through the primary winding161to the secondary winding162.

The node681feeds voltage Vhb (such as feedback signal Vhb) to the controller640. As further shown, the controller640includes comparator640. In one embodiment, during operation, comparator640compares a magnitude of the feedback signal Vhb to a threshold value TV6. The magnitude of the threshold value TV6can be set to any suitable value such as between a magnitude of the reference voltage291and magnitude of the input voltage120. Additional details of selecting a magnitude of the threshold value TV6is further discussed below with respect toFIGS.8A,8B,8C, and8D

In one embodiment, the controller640sets the magnitude of the threshold value TV6as a function of monitored voltage Vcr from node684. In another example embodiment, the controller640sets the magnitude of the threshold value TV6as a function of the monitored voltage Vzcd. In further example embodiments, the controller640sets the magnitude of the threshold value TV6as a function of monitored voltage Vcr and monitored voltage Vzcd.

In further example embodiments, the controller640sets the threshold value TV6with respect to a magnitude of the input voltage Vin. In such an instance, the controller640controls activation of the first switch121to an ON-state based at least in part on a difference between a magnitude of the signal Vhb and a magnitude of an input voltage Vin (120) converted by controlled switching (of switches121and122) into the output voltage Vout.

Based on the comparison of the feedback voltage signal Vhb to the threshold value TV6(threshold voltage TV6), the comparator640produces a respective trigger signal603, a state of which depends upon whether the feedback voltage signal Vhb is greater or less than the threshold voltage TV6. Thus, the comparator640detects when the magnitude of the feedback voltage signal Vhb crosses the respective threshold voltage TV6.

Delay timer655receives the trigger signal103, which serves as a basis in which to activate the delay timer655to measure an amount of time such as TD5and/or TD6as further discussed below.

FIG.7is an example timing diagram illustrating control signals and corresponding monitor signals according to embodiments herein.

As previously discussed, the controller640inFIG.6produces the respective control signals105in timing diagram700to control switches121and122. As shown, the magnitude of the signals Iout, Imag (a.k.a., magnetizing current in primary winding), Ihb, Vhb, Vcr, and Vzcd vary depending on control output switches via control signals105.

FIGS.8A,8B,8C, and8Dare example timing diagrams illustrating implementation of signal monitoring and switch control in a power converter to prevent cross conduction according to embodiments herein.

As previously discussed, the controller640monitors a magnitude of the feedback voltage signal Vhb produced by node681coupling the switch121and switch122. A magnitude of the monitored feedback voltage signal Vhb during the OFF state of the switch122is used as a basis to determine whether current flows through the body diode D2of the second switch122.

In one embodiment, the controller640sets a magnitude of the threshold value TV6based on one or more feedback signals (such as voltage Vcr, voltage Vcs, voltage Vzcd, etc.) For example, in one configuration, the controller640sets the threshold value TV6to be equal to A*Vcr+B, where A is a chosen gain value and B is a chosen offset value. In one embodiment, the controller640uses one or more samples of signal Vcr in window of time W1(between T80-1and T80-2such as around 50% to 75% into a range of switch122being ON between T80and T81, T85and T86, etc.) to generate the magnitude of the threshold value TV6.

Additionally, or alternatively, the controller640uses one or more samples of voltage Vzcd in window of time W1(between T80-1and T80-2such as around 50% to 75% of switch122being ON between T80and T81, T85and T86, etc.) to generate the magnitude of the threshold value TV6. For example, the controller640sets the threshold value TV6to be equal to A*Vzcd+B, where A is a chosen gain value and B is a chosen offset value.

In a further example, the controller640is operable to initiate activation of the first switch121after expiration of a predetermined delay amount of time TD5, which corresponds to a condition in which there is no current (such as Ihb) flowing through the body diode D2of the switch122. The predetermined time TD5can be as little as no time or a predetermined amount of time greater than zero.

As further shown,FIG.8Bindicates states of control signals105that control switch121and switch122.

For example, between time T80and time T81, the controller140controls a state of the driver642and corresponding control signal105-2to a logic high state while driver641drives control signal105-1to a logic low state. In such an instance, the current (Imag) decreases. The magnitude of the current Ihb also decreases. Activation of the switch122between time T80and T81causes the resonant circuit path (such as inductor L1, primary winding161, and capacitor C1) to dissipate energy in the corresponding resonant circuit path to convey energy from primary winding161to the secondary winding162, which is used to generate the output voltage123that powers the load118.

At time T81, the controller140produces the control signal105-2to a logic low resulting in the deactivation of the switch122. The diode D2of switch122conducts at least for a short amount of time after switch122is turned off. During the dead time when both of the switches121and122are in an OFF-state, after time T81, the comparator640compares the magnitude of the feedback voltage signal Vhb to the threshold level TV6.

In response to detecting at time or around time T82that the magnitude of the feedback voltage signal Vhb increases above the threshold voltage level TV6, the comparator640generates the trigger signal603(such as an edge trigger) to indicate the detected condition. Note that after voltage signal Vhb increases to a sufficient level, and after time duration TD5, it is safe to turn on the switch121again because it is known that the current through diode D2is zero or substantially zero.

As previously discussed, the trigger signal603(indicating that the magnitude of the signal Vhb crosses the threshold voltage TV6) causes the delay timer655to be activated. After expiration of the predetermined time delay TD5measured (by the delay timer655) with respect to time T82, the delay timer655changes a state of the control signal104(such as via falling edge) to indicate that it is time to activate the switch121again. In other words, after expiration of the time delay TD5with respect to time T82, the controller140activates the control signal105-1to a logic high state to activate the switch121.

Thus, time window between time T81and T83represents a dead time in which the controller140sets switches121and122to OFF states (logic low). The controller640uses a magnitude of the feedback signal Vhb as a basis to control switch121. Implementation of the delay TD5with respect to the trigger103(at time T82) ensures that there is substantially no current through the body diode D2at or around time T83when the switch121is activated to an on state again after time TD5. Thus, cross conduction is avoided.

Activation of the switch121to an ON-state (while switch122is OFF) between time duration T83to T84causes an increase in current Ihb through the primary winding161again as shown inFIG.8A. Activation of the switch121between time T83and T84causes the resonant circuit path (inductor L1, primary winding161, and capacitor C1) to store energy as well as convey energy from primary winding161to the secondary winding162, which is used to generate the output voltage123that powers the load118.

Accordingly, the controller140as described herein can be configured to implement a time delay between a time of detecting a condition in which the feedback voltage signal Vhb crosses a respective threshold voltage TV6and activating the switch121to the ON-state to ensure that there is no current flowing through the body diode D2when the switch121is activated to the ON-state.

Note that the time window between time T84and T85represents a dead time in which the controller640sets switches121and122to OFF states (logic low).

After time T85, in a window between time T85and T86, the control cycle then repeats in which the controller640initially activates the switch122to an ON state at time T85while switch121is turned OFF.

It should be noted that the magnitude of the feedback signal Vhb may not increase above the respective threshold value TV6during a respective control cycle. To accommodate such condition, the controller140and corresponding delay timer655can be configured to measure a second time delay TD6after detecting a condition in which the control signal105-2is reset from a high to a low state to deactivate the switch122. More specifically, at time T86, the controller deactivates the switch122to an OFF-state while switch121is also set to the OFF-state. In a similar manner as previously discussed, the controller140can be configured to monitor for a condition in which a magnitude of the feedback voltage Vhb crosses the threshold value TV6. This may not happen. For example, this does not happen between time T86and T87.

In response to detecting that the magnitude of the feedback signal Vhb does not increase above the threshold voltage TV8within the time delay TD6, but there is an expiration of time TD6started at time T86, the controller140sets the control signal105-1to the logic high state to turn on the switch121at time T87.

Note that the controller640can be configured to simultaneously monitor for both of the conditions as previously discussed. For example, for each of multiple control cycles (such as between time T80and time T85, between time T85and time T89, etc.), the controller640monitors for the occurrence of the voltage Vhb increasing above a respective threshold value TV6within a time delay TD6of the activating the low side switch122. If the controller640detects this condition (Vhb>TV6), the controller640activates the switch121again after a time delay of TD5with respect to a crossing of the voltage Vhb with respect to the threshold value TV6. If the controller640does not detect the voltage Vhb crossing the threshold value TV6within time duration TD6, the controller640activates the switch121again after a time delay of TD6with respect to the activating the switch122to the OFF-state.

FIG.9is an example diagram illustrating a more detailed rendition of a power supply and corresponding controller according to embodiments herein.

In this example embodiment, the switch121is instantiated as a field effect transistor including a body diode D1, a gate (G), drain (D), and source (S). Additionally, the switch122is instantiated as a field effect transistor including a body diode D2, a gate (G), drain (D), and source (S).

Driver641(such as high side switch driver circuitry) of the controller640is electrically connected to the gate of switch121. The drain node of the switch121is connected to receive the input voltage120. At node981, the source node of the switch121is connected to the drain node of switch122. Switch121and switch122are connected in series.

Driver642(such as low side switch driver circuitry) of the controller640is electrically connected to drive the gate of switch122. The source node of switch122is connected to a first ground reference potential291.

As further shown, the body diode D1(inherent or parasitic diode) is disposed between the source node of switch121and the drain node of switch121. The body diode D2is connected between the source node of switch122and the drain node of switch122.

In accordance with further embodiments, the power supply100includes a resonant circuit path (combination of inductor L1, primary winding161, and capacitor C1) disposed between the node981and the node982(input voltage120).

The body diode D2(inherent or parasitic diode) of switch122is disposed between the source node of switch122and the drain node of switch122.

As further shown, the secondary winding162is connected between node983and the diode D3. The combination of secondary winding162and diode D3are connected in series between node983and the second ground reference potential292.

Capacitor Cout is connected between node983and the second ground reference potential292.

As previously discussed, the primary winding161of the transformer660is disposed in a resonant circuit path such as the circuit path including a combination of the inductor L1, primary winding161, and the capacitor C1(a.k.a., Cr). The controller640controls a magnitude of the switching frequency associated with the control signals105based upon the resonant frequency associated with the resonant circuit path.

As previously discussed, the node981feeds voltage Vhb (such as feedback signal Vhb) to the controller640. As further shown, the controller640includes comparator640. In one embodiment, during operation, comparator640compares a magnitude of the feedback signal Vhb to a threshold value TV7. The magnitude of the threshold value TV7can be set to any suitable value such as between a magnitude of the reference voltage291and magnitude of the input voltage120.

Additional details of selecting a magnitude of the threshold value TV7is further discussed below with respect toFIGS.11A,11B,11C, and11D

In one embodiment, the controller640sets the magnitude of the threshold value TV7as a function of monitored voltage Vcr. In another example embodiment, the controller640sets the magnitude of the threshold value TV7as a function of the monitored voltage Vzcd. In further example embodiments, the controller640sets the magnitude of the threshold value TV7as a function of monitored voltage Vcr and monitored voltage Vzcd.

Based on the comparison of the feedback voltage signal Vhb to the threshold value TV7, the comparator640produces a respective trigger signal603, a state of which depends upon whether the feedback voltage signal Vhb is greater or less than the threshold voltage TV7. Thus, the comparator640detects when the magnitude of the feedback voltage signal Vhb crosses the respective threshold voltage TV7. If desired, the threshold value TV7can be selected as a function input voltage120. The controller640can be configured to control activation of the switch122to an ON state based at least in part on a difference between a magnitude of the signal Vhb and a magnitude of an input voltage120converted by controlled switching of switches121and122into the output voltage123.

Delay timer655receives the trigger signal603, which serves as a basis in which to activate the delay timer655and measure time.

More specifically, as further discussed below (such as inFIGS.11A,11B,11C, and11D), after expiry of a time delay (such as time delay TD7) as measured by timer655with respect to a trigger event as indicated by trigger signal603, the controller640controls the driver641to activate the switch121to an ON-state subsequent to a time of deactivating the switch121to an OFF-state. For example, upon expiry of the time delay TD7with respect to shutting OFF switch121, the timer755outputs control signal104, which provides a basis in which to control timing and generation of control signal105-2at an appropriate time with respect to control signal105-1such that there is no (or substantially no) cross-conduction when switch122is activated to an ON-state. In other words, to prevent cross conduction, as further discussed herein, the controller140prevents activation of switch122until after a condition in which the body diode D1no longer conducts and current no longer flows through the body diode D1. This is further illustrated inFIG.10andFIGS.11A,11B,11C, and11D.

FIG.10is an example timing diagram illustrating control signals and corresponding monitor signals according to embodiments herein.

As previously discussed, the controller640inFIG.9produces the respective control signals105in timing diagram1000to control switches121and122. As shown, the magnitude of the signals Iout, Imag (a.k.a., magnetizing current in primary winding), Ihb, Vhb, Vcr, and Vzcd vary depending on control output switches via control signals105.

FIGS.11A,11B,11C, and11Dare example timing diagrams illustrating implementation of signal monitoring and switch control in a power converter to prevent cross conduction according to embodiments herein.

As previously discussed, the controller140monitors a magnitude of the feedback voltage signal Vhb produced by node981coupling the switch121and switch122. A magnitude of the monitored feedback voltage signal Vhb during the OFF state of the switch122is used as a basis to determine whether current flows through the body diode D2of the second switch122.

In one embodiment, the controller640sets a magnitude of the threshold value TV7based on one or more feedback signals (such as voltage Vcr, voltage Vcs, voltage Vzcd, etc.)

For example, the controller640sets the threshold value TV7to be equal to A*Vcr+B, where A is a chosen gain value and B is a chosen offset value. In one embodiment, the controller640uses one or more samples of signal Vcr in window of time W3(between T90-1and T90-2such as around 50% to 75% into a range of switch121being ON between T80and T81, T85and T86, etc.) to generate the magnitude of the threshold value TV7.

Additionally, or alternatively, the controller640uses one or more samples of voltage Vzcd in window of time W3(between T90-1and T90-2such as around 50% to 75% of switch121being ON between T90and T91, T95and T96, etc.) to generate the magnitude of the threshold value TV7. For example, the controller640sets the threshold value TV7to be equal to A*Vzcd+B, where A is a chosen gain value and B is a chosen offset value.

In one embodiment, the controller140is further operable to initiate activation of the first switch122after expiration of a predetermined delay amount of time TD7, which corresponds to a condition in which there is no current (such as Ihb) flowing through the body diode D1of the switch121. The predetermined time TD7can be as little as no time or a predetermined amount of time greater than zero.

As further shown,FIG.11Bindicates states of control signals105that control switch121and switch122.

For example, between time T90and time T91, the controller640controls a state of the driver641and corresponding control signal105-1to a logic high state while driver642drives control signal105-2to a logic low state. In such an instance, the current (Imag) decreases. The magnitude of the current Ihb also decreases.

At time T91, the controller640produces the control signal105-1to a logic low resulting in the deactivation of the switch121. The diode D1of switch121conducts at least for a short amount of time after it is turned off. During the dead time when both of the switches121and122are in an OFF-state, after time T91, the comparator640compares the magnitude of the feedback voltage signal Vhb to the threshold level TV7.

In response to detecting at time or around time T92that the magnitude of the feedback voltage signal Vhb decreases below the threshold voltage level TV7, the comparator640generates the trigger signal103(such as an edge trigger) to indicate the detected condition. Note that after voltage signal Vhb decreases to a sufficient level, it is safe to turn on the switch122again because it is known that the current through diode D1zero or substantially zero.

As previously discussed, the trigger signal103(indicating that the magnitude of the signal Vhb crosses the threshold voltage TV7) causes the delay timer655to be activated. After expiration of the predetermined time delay TD7measured (by the delay timer655) with respect to time T92, the delay timer655changes a state of the control signal104(such as via falling edge) to indicate that it is time to activate the switch122again. In other words, after expiration of the time delay TD7at time T93, the controller640activates the control signal105-2to a logic high state to activate the switch122.

Thus, time window between time T91and T93represents a dead time in which the controller640sets switches121and122to OFF states (logic low). The controller640uses a magnitude of the feedback signal Vhb as a basis to control switch122. Implementation of the delay TD7with respect to the trigger103(at time T92) ensures that there is no current through the body diode D1at or around time T93when the switch122is activated to an on state again after time TD7. Thus, cross conduction between switch122being ON and current flowing through the diode D1is avoided.

Accordingly, the controller640as described herein can be configured to implement a time delay TD7between a time of detecting a condition in which the feedback voltage signal Vhb crosses a respective threshold voltage TV7and activating the switch122to the ON-state to ensure that there is no current flowing through the body diode D1when the switch122is activated to the on state.

Note that the time window between time T94and T95represents a dead time in which the controller140sets switches121and122to OFF states (logic low).

After time T95, in a window between time T95and T96, the control cycle then repeats in which the controller640initially activates the switch121to an ON state at time T95while switch122is turned OFF.

It should be noted that the magnitude of the feedback signal Vhb may not decrease below the respective threshold value TV7during a respective control cycle. To accommodate such a condition, the controller640and corresponding delay timer655can be configured to measure a second time delay TD8after detecting a condition in which the control signal105-1is set to a low state to deactivate the switch121. More specifically, at time T96, the controller deactivates the switch121to an OFF-state while switch122is also set to the OFF-state. In a similar manner as previously discussed, the controller640can be configured to monitor for a condition in which a magnitude of the feedback voltage Vhb crosses the threshold value TV7. This may not happen. For example, this does not happen between time T96and T97.

In response to detecting that the magnitude of the feedback signal Vhb does not decrease below the threshold voltage TV7within the time delay TD8with respect to time T96, the controller140sets the control signal105-2to the logic high state to turn on the switch122at time T97.

Note that the controller640can be configured to simultaneously monitor for both of the conditions as previously discussed. For example, for each of multiple control cycles (such as between time T90and time T95, between time T95and time T99, etc.), the controller640monitors for the occurrence of the voltage Vhb decreasing below a respective threshold value TV7within a time delay TD8of the deactivating the low side switch121. If the controller640detects this condition (Vhb<TV7), the controller640activates the switch121again after a time delay of TD7with respect to a crossing of the voltage Vhb with respect to the threshold value TV7. If the controller640does not detect the voltage Vhb crossing the threshold value TV7by expiration of time TD8, the controller640activates the switch122again.

FIG.12is an example block diagram of a computer system for implementing any of the operations as previously discussed according to embodiments herein.

Any of the resources (such as controller140, etc.) as discussed herein can be configured to include computer processor hardware and/or corresponding executable instructions to carry out the different operations as discussed herein.

As shown, computer system1250of the present example includes an interconnect1211that couples computer readable storage media1212such as a non-transitory type of media (which can be any suitable type of hardware storage medium in which digital information can be stored and retrieved), a processor1213(computer processor hardware), I/O interface1214, and a communications interface1217.

I/O interface(s)1214supports connectivity to voltage converter110.

Computer readable storage medium1212can be any hardware storage device such as memory, optical storage, hard drive, floppy disk, etc. In one embodiment, the computer readable storage medium1212stores instructions and/or data.

As shown, computer readable storage media1212can be encoded with controller application140-1(e.g., including instructions) to carry out any of the operations as discussed herein.

During operation of one embodiment, processor1213accesses computer readable storage media1212via the use of interconnect1211in order to launch, run, execute, interpret or otherwise perform the instructions in controller application140-1stored on computer readable storage medium1212. Execution of the controller application140-1produces controller process140-2to carry out any of the operations and/or processes as discussed herein.

Those skilled in the art will understand that the computer system1250can include other processes and/or software and hardware components, such as an operating system that controls allocation and use of hardware resources to execute controller application140-1.

In accordance with different embodiments, note that computer system may reside in any of various types of devices, including, but not limited to, a power supply, switched-capacitor converter, power converter, a mobile computer, a personal computer system, a wireless device, a wireless access point, a base station, phone device, desktop computer, laptop, notebook, netbook computer, mainframe computer system, handheld computer, workstation, network computer, application server, storage device, a consumer electronics device such as a camera, camcorder, set top box, mobile device, video game console, handheld video game device, a peripheral device such as a switch, modem, router, set-top box, content management device, handheld remote control device, any type of computing or electronic device, etc. The computer system1250may reside at any location or can be included in any suitable resource in any network environment to implement functionality as discussed herein.

Functionality supported by the different resources will now be discussed via flowcharts inFIG.13. Note that the steps in the flowcharts below can be executed in any suitable order.

FIG.13is a flowchart1300illustrating an example method according to embodiments herein. Note that there will be some overlap with respect to concepts as discussed above.

In processing operation1310, the controller140controls switching of a first switch and a second switch in a power supply (such as a resonant power converter) to regulate conveyance of energy from a primary winding161of a transformer160in the resonant power converter to a secondary winding162of the transformer to generate an output voltage123that powers a load118. The primary winding161and a resonant capacitor C1disposed in a resonant circuit path of the resonant power converter (power supply100).

In processing operation1320, the controller140receives a first signal (Vhb) generated from a first node coupling the first switch and the second switch.

In processing operation1330, the controller140controls activation of the first switch to an ON-state based at least in part on the first signal (Vhb).

Note again that techniques herein are well suited for use in power supply applications. However, it should be noted that embodiments herein are not limited to use in such applications and that the techniques discussed herein are well suited for other applications as well.

While this invention has been particularly shown and described with references to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present application as defined by the appended claims. Such variations are intended to be covered by the scope of this present application. As such, the foregoing description of embodiments of the present application is not intended to be limiting. Rather, any limitations to the invention are presented in the following claims.