Temperature control of power devices

Abstract

In described examples, a circuit (100) includes a power device (102) having a voltage input (104, 106) and a command input (108). A sense circuit (110) has a sensor input (112) and a sensor output (114), with the sensor input coupled to the power device (102). A control circuit (118) has a control input (120) and a control output (122), with the control input coupled to the sensor output (114). A driver circuit (124) has a driver input and a driver output. The driver input is coupled to the control output (122), and the driver output is coupled to the command input (108) of the power device (102).

Description

Technical Field

[0001] This invention relates to the temperature control of a power device. Background Technology

[0002] Avalanche breakdown involves a phenomenon that can occur in either insulating or semiconducting materials when the electric field across the pn junction has sufficient energy to generate free charge carriers that collide with bound electrons, producing more free charge carriers. The increase in free charge carriers leads to a significant increase in current through the pn junction. During overvoltage stress conditions, power devices can experience excessive power dissipation in response to avalanche breakdown. Increased power loss induces temperature rise in the junction of the power device and its encapsulated package. In some cases, this temperature rise can cause device damage (e.g., package delamination). Summary of the Invention

[0003] In the described example, a circuit includes a power device having a voltage input and a command input. A sensing circuit has a sensor input and a sensor output, wherein the sensor input is coupled to the power device. A control circuit has a control input and a control output, wherein the control input is coupled to the sensor output. A driver circuit has a driver input and a driver output. The driver input is coupled to the control output, and the driver output is coupled to the command input of the power device.

[0004] In another described example, a circuit includes a power device having a voltage input terminal and a command input. The power device is configured to conduct current between the voltage inputs in response to a control input signal. A thermal sensor is configured to sense the temperature of the power device and provide a sensor signal in response to the sensed temperature. A driver circuit is configured to provide a driver signal to the command input of the power device to turn on the power device and to reduce the temperature of the power device in response to the sensor signal.

[0005] In another described example, a system includes an integrated circuit (IC) having a voltage input terminal. The IC includes a power device having an input terminal and a command input, the input terminal of the power device being coupled to the voltage input terminal of the IC. The IC also includes a sensor coupled to the power device, the sensor being configured to provide a sensor signal in response to detecting an overload event of the power device. The IC further includes the command input coupled to the power device and configured to drive driver circuitry of the power device in response to the sensor signal. The test system includes a voltage source coupled to the voltage input terminal and configured to provide a test voltage to induce the overload event of the power device. Attached Figure Description

[0006] Figure 1This is a block diagram illustrating an example circuit configured to control the temperature of a power device.

[0007] Figure 2 Describe an example circuit configured to control the temperature of a power device.

[0008] Figure 3 Describe an example of a temperature control circuit.

[0009] Figure 4 Describe another example circuit configured to control the temperature of a power device.

[0010] Figure 5 An exemplary system is described, comprising a power device and a circuit configured to control the temperature of the power device during a high potential test.

[0011] Figure 6 It is a display Figure 5 The signal diagram of the system is a curve. Detailed Implementation

[0012] Exemplary embodiments relate to circuit systems and methods for controlling the temperature of power devices. As used herein, the term "power device" refers to a semiconductor device that can be implemented in an integrated circuit (IC) chip and used as a switch or rectifier or other type of power electronic device. Examples of power devices include metal-oxide-semiconductor field-effect transistors (MOSFETs), insulated-gate bipolar transistors (IGBTs), bipolar junction transistors (BJTs), laterally diffused metal-oxide-semiconductor (LDMOS) FETs, etc.

[0013] In one example, a circuit includes a power device having a voltage input and a control input. A sensing circuit has a sensor input and a sensor output, wherein the sensor input is coupled to the power device. A control circuit has a control input and a control output, wherein the control input is coupled to the sensor output. The control circuit may be implemented as part of the sensing circuit or as a separate circuit. A driver circuit has a driver input and a driver output. The driver input is coupled to the control input, and the driver output is coupled to the control input of the power device. For example, the sensing circuit is configured to sense an overload condition of the power device, such as by sensing the temperature, voltage, or current of the power device. The control circuit is configured to modulate a control signal at the driver input in response to the sensed overload condition. Therefore, the power device is operated during the sensed overload condition in response to the control signal to correspondingly reduce the temperature of the power device.

[0014] Figure 1This is a block diagram illustrating an exemplary circuit 100. Circuit 100 includes a power device 102 having voltage inputs 104 and 106 and a command input 108. For example, the power device includes one or more transistors coupled between inputs 104 and 106. Thus, the power device 102 can be implemented as a metal-oxide-semiconductor field-effect transistor (MOSFET), a bipolar junction transistor (BJT), a junction field-effect transistor (JFET), an insulated-gate bipolar transistor (IGBT), or other types of transistors. In this example, the power device is implemented as a power MOSFET, which includes a body diode coupled between the source and drain of the MOSFET coupled to inputs 104 and 106. When a reverse bias is applied between the drain and source, an electric field is established across the PN junction of the body diode. When the applied voltage increases beyond the breakdown voltage, a critical field is reached where the junction no longer supports the applied voltage. The increased voltage causes avalanche breakdown in which a reverse current flows through the body diode.

[0015] The circuit also includes sensing circuitry 110 having sensor input 112 and sensor output 114. Sensor input 112 is coupled to power device 102. For example, the coupling schematically shown at 116 may include conductive coupling such as a conductive and / or thermally conductive connection. Sensing circuitry 110 is configured to detect avalanche conditions of power device 102 and provide a sensor signal representing the sensed avalanche condition. As used herein, the term “avalanche condition” refers to an insulating region (e.g., a pn junction of a semiconductor power device) of power device 102 that is electrically broken down in response to an applied electric field. For example, when the power device is off (e.g., inactive) (such as during a high potential (HIPOT) test), a sufficiently high voltage and / or current is applied to the inputs 104 and 106 of the power device to generate an electric field sufficient to trigger an electrical breakdown across the insulating region of the power device. Thus, current may flow through the power device in response to the electrical breakdown. Sensing circuitry may sense the temperature and / or electrical characteristics of the power device to detect overload (e.g., avalanche) conditions.

[0016] In one example, sensing circuit 110 is a thermal sensor disposed adjacent to power device 102 and configured to measure the temperature of the power device and provide a sensor signal representing the temperature. In another example, sensing circuit 110 is configured to measure the electrical characteristics (e.g., voltage, current, power) of power device 102 (such as the voltage and / or current of the power device) and provide a sensor signal in response to the measured electrical characteristics. In another example, circuit 100 is implemented as an IC comprising power device 102 and sensing circuit 110 on a common substrate (e.g., a die) within IC packaging material.

[0017] Circuit 100 further includes control circuitry 118 having control input 120 and control output 122. Control input 120 is coupled to sensor output 114. Control output 122 is coupled to driver input of driver circuitry 124. Control circuitry 118 is configured to provide a control signal to driver circuitry 124 in response to a sensor signal. For example, control circuitry 118 is configured to compare the sensor signal with a threshold and provide the control signal as a pulse or pulse sequence in response to the sensor signal indicating an avalanche condition of the power device. Figure 1 In one example, the control circuit 118 and the sensing circuit 110 are shown as separate circuits. In another example, the sensing circuit 110 and the control circuit 118 may be combined in a circuit system configured to perform corresponding sensing and control functions.

[0018] Driver circuit 124 has a driver output coupled to command input 108 of the power device. Driver circuit 124 is configured to supply a drive signal to the command input in response to a control signal at 122. The power device is configured to activate (e.g., turn on) in response to the drive signal to reduce the power consumed by the power device during avalanche conditions.

[0019] For example, sensing circuit 110, control circuit 118, and driver circuit 124 are configured as an "on" control loop to regulate the operation of power device 102 during avalanche conditions. In one example, control circuit 118 is configured to provide a control signal as a pulse with a duty cycle in response to a sensor signal. The duty cycle of the control signal may be fixed or may vary over time. For example, the duty cycle may be set in response to temperature changes in the power device. Control circuit 118 may be configured to repeatedly activate the power device to conduct current at a first temperature threshold and then deactivate the power device when a lower temperature threshold is reached, such as providing hysteresis control in response to device temperature. Thus, by activating (e.g., turning on) power device 102 in response to the detection of an avalanche condition, the power device consumes less power. Reduced power consumption further enables a reduction in the temperature of the power device.

[0020] As another example, test system 128 is shown coupled to circuit 100. Test system 128 includes a voltage source 130 coupled in series with a limiting resistor RLIM between the voltage inputs 104 and 106 of the power device. In this example, the circuit is implemented as IC 132 and the voltage inputs 104 and 106 of the power device are coupled to terminals 134 and 136 of IC 132. Therefore, as Figure 1As shown, the RLIM and voltage source can be coupled to terminals 134 and 136, such as for testing circuitry in an IC. For example, the voltage source is configured to perform HIPOT by applying a high-stress voltage, which can be up to about five times the normal blocking requirements of the power device. Such high-stress voltages tend to increase the power consumption of the power device, which also raises the die temperature. For example, elevated die temperature can damage the IC package, such as causing delamination. Existing methods for reducing power consumption include increasing the size of the RLIM or adding clamping circuitry across terminals 134 and 136. Both of these significantly increase the cost of circuitry 100. The method used herein, which activates power device 102 in response to the detection of an overload event (such as avalanche breakdown) of the power device, allows for a reduction in the size (and cost) of the RLIM compared to existing methods. Furthermore, the method described herein eliminates the need for additional (expensive) clamping circuitry.

[0021] Figure 2 An exemplary circuit 200 configured to control the temperature of power device 102 is depicted. Circuit 200 is... Figure 1 An exemplary embodiment of the circuit 100 shown herein. Therefore, Figure 2 The description also references Figure 1 .exist Figure 2 In one example, power device 102 includes a pair of power FETs 202 and 204 series coupled between voltage input terminals 206 and 208. Specifically, FETs 202 and 204 are shown in a common-source configuration, wherein the sources of each FET are coupled together. The common-source configuration is used to provide bidirectional voltage blocking. The drain of each FET 202 and 204 is coupled to the respective input terminals 206 and 208. Each of FETs 202 and 204 also includes body diodes 210 and 212 coupled between the respective source and drain of the FET. Body diodes 210 and 212 have semiconductor junctions configured to block reverse current from the drain to the source of the respective FETs 202 and 204.

[0022] Circuit 200 also includes a thermal sensor 214 coupled to power device 102. Figure 2In this example, the thermal sensor 214 has a voltage input 215 coupled to a transistor 216. For example, the transistor 216 is a JFET coupled between terminal 206 and the input 215 of the thermal sensor 214, with the source of the JFET coupled to the voltage input 215. The voltage input 215 is also coupled to a voltage input of a driver 218. The JFET 216 is configured to operate the thermal sensor 214 and the driver 218, such as by supplying an input voltage in response to a voltage potential applied across terminals 206 and 208. For example, when the gate of the JFET is grounded, the JFET is configured (e.g., operating in pinch-off mode) to provide a low voltage supply (e.g., about 5 to 20V) at its source to operate the control circuitry. When the drain of the JFET is low, the JFET is configured (e.g., operating in the transistor region) to behave like a switch, cutting off the control circuitry. The output 220 of the thermal sensor 214 is coupled to the input of the driver 218. The driver 218 has an output coupled to the gate of the FET 202. The gate of FET 204 is coupled to the common source terminal of FETs 202 and 204. The thermal sensor 214 and the driver 218 have a ground terminal that is also coupled to the common source terminal of FETs 202 and 204.

[0023] In other instances, different methods may be used. Figure 2 The number and arrangement of one or more power devices 102 shown in the figure. Figure 2 In examples of this and others, circuit 200 may include one or more examples of thermal sensors 214 and drivers 218 (or other circuitry) configured to drive the corresponding power device 102 in response to the detection of avalanche conditions. Similarly, separate sensing and control circuitry systems, such as those described herein, may be implemented to control the power device 102 in response to the detection of avalanche conditions.

[0024] Thermal sensor 214 is configured to provide a sensor signal at output 220 in response to the temperature of the power device. Driver 218 is configured to control power device 102 in response to the sensor signal. In one example, thermal sensor 214 is implemented as a “shutdown” sensor of power device 102 (via driver 218) in response to a sensed temperature exceeding a temperature threshold. The temperature threshold may be configurable. In another example, thermal sensor 214 is configured to implement hysteresis control, wherein the thermal sensor provides a logic high sensor signal to turn on FET 202 in response to a temperature exceeding a first threshold and provides a logic low sensor signal to turn off FET 202 in response to a temperature dropping below a second threshold. Thus, FET 202 is turned on and off (e.g., switched) in response to the duty cycle of the sensor output signal, and the duty cycle of the sensor signal is responsive to the temperature of power device 102.

[0025] As another example, terminals 206 and 208 are adapted to couple to test system 211. For example, similar to Figure 1 The test system 211 includes a resistor RLIM series coupled between terminals 206 and 208 and a voltage source 130. The voltage source 130 is configured to provide an output voltage (shown as VHIPOT) such as for test circuit 200. Therefore, in response to the application of voltage VHIPOT across terminals 206 and 208, avalanche breakdown occurs across the PN junction of the body diode 210 of FET 202 to provide current flowing through the channel of FET 202. Diode 212 can be forward biased to conduct current through FET 204. Power will be consumed in response to avalanche conditions, causing the power device 102 to heat up. As described above, a thermal sensor 214 is configured to provide a sensor signal in response to the sensed temperature to control FET 202 and thereby regulate the temperature of the power device.

[0026] In this example, circuit 200 is implemented as IC 234, which includes a power device 102, a thermal sensor 214, a driver 218, and a transistor 216 implemented on a common substrate (e.g., a semiconductor die). In the exemplary IC 234, the thermal sensor measures the temperature of the die at the location where the thermal sensor is implemented, which depends on the temperature of the power device 102.

[0027] Figure 3 The display can be used Figure 2 An example of thermal sensor 214 in the examples. Therefore, Figure 3 The description also references Figure 2The thermal sensor 214 includes current sources 302 and 304. A switch (e.g., a FET) 306 is coupled in series with current source 304, which is connected in parallel with current source 302. In one example, current source 302 is a PTAT-proportional current source configured to provide a current in response to (e.g., proportional to) the temperature of the substrate on which the current source is formed. Another current source 304 may also be a PTAT current source. A resistor R1 is coupled between voltage terminal 308 and junction (e.g., terminal) 310 to which current source 302 and switch 306 are coupled. Terminal 310 is also coupled to the base of transistor 312. The emitter of transistor 312 is coupled to terminal 308, and the collector of transistor 312 is coupled to ground via another current source 314 configured to draw current from the collector of transistor 312. Due to the PTAT characteristics of current sources 304 and 302, the voltage difference between the voltages at 308 and 310 (e.g., the emitter-base voltage of 312) increases in response to a rise in temperature to control transistor 312. Transistor 312 is activated to couple the output 220 of the thermal sensor to a voltage terminal in response to a rise in temperature of the input supplied to driver 218. In this example, the output 220 of the thermal sensor is used to control the state of switch 306 such that when 220 is logic high, switch 306 is enabled and exhibits a hysteresis response to temperature. Therefore, the sensor output at 220 may have a duty cycle responsive to the sensed temperature (e.g., due to enabling or disabling the hysteresis of PTAT current source 302 using switch 306).

[0028] Figure 4 An exemplary circuit 400 configured to control the temperature of power device 102 is depicted. Circuit 400 is... Figure 1 Another exemplary embodiment of the circuit 100 shown herein. Therefore, Figure 4 The description also references Figure 1 .exist Figure 4 In one example, power device 102 includes a FET 402 coupled between voltage input terminals 406 and 408. Similar to... Figure 2 As described, FET 402 also includes a body diode 410 coupled between the respective source and drain of the FET. The body diode 410 has a semiconductor junction configured to block reverse current from the drain to the source of the respective FET 402.

[0029] Circuit 400 also includes a sensor for detecting overload conditions. Figure 4In this example, the sensor is implemented as a voltage sensor 414 having first and second inputs 416 and 418 and a sensor output 420. The first input is coupled to the drain of FET 402 and the second input is coupled to the source of FET 402. Sensor output 420 is coupled to the input of a single trigger circuit 422. The single trigger circuit 422 has an output 424 coupled to the input of a driver circuit 426. The driver circuit 426 has an output coupled to a control input (e.g., the gate of FET 402) of the power device 102.

[0030] Voltage sensor 414 is configured to measure the voltage across FET 402, and also provides a measurement of the voltage across body diode 410. Voltage sensor 414 provides a sensor output signal at output 420 representing the sensed voltage across FET 402. For example, voltage sensor 414 is implemented as a voltage divider circuit (e.g., a resistive voltage divider) configured to provide a voltage representing the drain voltage of FET 402. A comparator compares the voltage divider output with a reference, such that the comparator provides a first output (e.g., logic high) when the measured voltage exceeds the reference and a second output (e.g., logic low) when the measured voltage does not exceed the reference. In other instances, different configurations of circuitry can be used to implement voltage sensor 414. Single trigger circuit 422 is configured to control a driver in response to the sensor output signal at 420, such as by providing a trigger pulse signal with a duration. The duration of the trigger pulse signal at 424 can be fixed and configurable. Driver circuit 426 is configured to drive a power device in response to the trigger pulse at 424. The driver circuit 426 also has a supply input coupled to a transistor (e.g., a JFET) 428. Therefore, the JFET is configured to provide a supply voltage to the driver circuit 426, and the driver circuit provides a drive signal (with amplitude) to the power device in response to a voltage drop across the transistor 428.

[0031] As an example, terminals 406 and 408 are adapted to couple to test system 430. Similar to... Figure 2Test system 430 may include resistor RLIM and voltage source 130. Voltage source 130 is configured to provide an output voltage VHIPOT, such as for test circuit 400. For example, when FET 402 is off and not experiencing avalanche breakdown, the power consumed in FET 402 is not a concern due to heat (e.g., in the sub-mW range). If the voltage applied across 406 and 408 (e.g., VHIPOT) exceeds the breakdown voltage of FET 402, an avalanche condition occurs, in which body diode 410 is reverse biased to conduct current from drain to source. During the avalanche condition, voltage sensor 414 measures the voltage across FET 402, which is approximately equal to the voltage at 406 (e.g., VHIPOT minus the voltage drop across RLIM). Voltage sensor 414 may provide a sensor signal in response to the detected voltage to drive the input of a single-trigger circuit. A single-trigger circuit is configured to supply a pulse of duration to trigger driver circuit 426 to drive the gate of FET 402 (e.g., to have a gate-to-source voltage of FET 402 sufficient to turn on the FET) and turn on the FET to conduct current through its channel for a time interval equal to the duration of the single-trigger pulse. As described herein, the FET dissipates less heat and cools down when it is on. After the duration, the driver removes the voltage from the gate of FET 402 and the FET turns off. Assuming VHIPOT is still provided, the FET will undergo avalanche breakdown and heat dissipation. In response to avalanche breakdown, voltage sensor 414 triggers single-trigger circuit 422 to turn on the FET for a duration. This process can be repeated during the application of VHIPOT to regulate the temperature of power devices and, more generally, circuit 400 (e.g., implemented as an IC), as described herein.

[0032] Figure 5 An example of a system 502 is depicted, comprising IC 500, control circuitry 504, and test system 506. Figure 5 In one example, IC 500 includes an isolation barrier 508 configured to electrically isolate one set of circuit systems 510 from another set of circuit systems 512. Circuit system 512 includes power devices 102 (such as...). Figure 1 As shown in the diagram, it includes FETs 514 and 516 coupled between corresponding terminals 518 and 520. A test system 506 is coupled to terminals 518 and 520. For example, the test system 506 includes a voltage source 130, a resistor RLIM, and another resistor R3 (e.g., RLIM > R3). A driver 522 is coupled to the gates of FETs 514 and 516 to drive the power device 102 in response to an input control signal.

[0033] For example, control circuitry 504 is configured to apply an enable input signal to input terminal 524. Isolation driver 526 has an input coupled to terminal 524. Isolation driver 526 is configured to provide an isolation control signal that can be converted back to an electrical signal through an isolation barrier (e.g., as an optical signal), the electrical signal serving as an input control signal for driver 522 to control power device 102.

[0034] System 502 also includes protection circuitry 530. In one example, protection circuitry 530 is implemented as part of circuit system 512 in IC 500. In another example, protection circuitry 530 is implemented as part of control circuitry 504. In yet another example, protection circuitry 530 may be distributed between circuit system 512 and control circuitry 504. Protection circuitry 530 is configured to regulate the junction temperature of power device 102 during overload conditions (such as avalanche conditions). For example, protection circuitry 530 is configured to, according to the provisions of this document (including...) Figure 1 , 2 Sensing and control can be implemented using any of the examples described in 3 and 4). Because the protection circuitry can effectively regulate the temperature of the power device 102 (including each of FETs 514 and 516) and IC 500, a smaller resistor RLIM can be used in system 502 than in existing methods.

[0035] As another example, Figure 6 It is a display Figure 5The system's signal graphs 602, 604, 606, 608, and 610 are plotted in graph 600. Graph 602 shows an example of a test signal supplied by voltage source 130 during a test interval (e.g., approximately 60 seconds). Graph 604 shows an example of current supplied at terminal 518 in response to the test voltage and operation of protection circuit 530, as described herein. Therefore, during operation of protection circuit 530, the current switches according to a duty cycle in response to switching the duty cycles of FETs 514 and 516. Graph 606 shows the voltage drop across resistor RLIM in response to the test current (Graph 604). As shown, in Graph 606, an increased voltage drop occurs across RLIM in response to turning on FETs 514 and 516. Graph 608 shows the input voltage (VIN) across input terminals 518 and 520. A wider pulse 612 initially occurs in response to the test signal VHIPOT because the protection circuit 530 has not yet triggered FETs 514 and 516 to turn on. After the temperature rises due to the test voltage VHIPOT, the protection circuit 530 is configured to control the FETs such that the input voltage 608 has the corresponding duty cycle shown (e.g., after approximately 4 seconds). Figure 610 illustrates an example of the sensed temperature (e.g., the junction temperature of FET 514) of the power device 102. Thus, Figure 610 illustrates that the junction temperature initially rises at 614 and then hysteretly regulates during high-stress conditions (e.g., during the application of VHIPOT to IC 500). As described herein, if the protection circuit 530 does not implement temperature regulation, the temperature may continue to rise, which could cause irreparable damage to IC 500 (e.g., package delamination). After VHIPOT is removed, the power device 102 returns to normal operation and is able to block an input voltage at 518 that does not exceed the breakdown voltage of FET 514.

[0036] In this invention, the term "coupled" means either an indirect or direct connection. Therefore, if a first device is coupled to a second device, the connection can be either a direct connection or an indirect connection via other devices and connections. For example, if device A generates a signal to control device B to perform an action, then in a first instance, device A is coupled to device B, or in a second instance, device A is coupled to device B via an intermediary component C, where the intermediary component C substantially does not alter the functional relationship between device A and device B, such that device B is controlled by the control signal generated by device A.

[0037] The expression "based on" implies "at least partially based on". Therefore, if X is based on Y, then X can be a function of Y and various other factors.

[0038] Within the scope of the claims, modifications to the described embodiments are possible, and other embodiments are also possible.

Claims

1. A circuit for controlling the temperature of a power device, comprising: A power device having a first voltage terminal, a second voltage terminal, and a command input; A sensing circuit having a sensor input and a sensor output, the sensor input being coupled to the power device, the sensing circuit being configured to detect overload events of the power device; A control circuit having a control input and a control output, wherein the control input is coupled to the sensor output; A driver circuit having a driver input and a driver output, the driver input being coupled to the control output and the driver output being coupled to the command input of the power device, wherein the driver circuit is configured to supply a drive signal to the command input in response to the overload event to activate the power device to conduct current, wherein the driver circuit does not include a clamping circuit system. and A transistor coupled between a first voltage terminal and a power supply terminal of the driver circuit, the transistor having a control terminal coupled to the second voltage terminal, wherein the transistor is configured to provide an input voltage from the first voltage terminal to the power supply terminal of the driver circuit in response to a voltage potential at the second voltage terminal.

2. The circuit of claim 1, wherein the sensing circuit includes a thermal sensor circuit coupled to the power device, the thermal sensor circuit having a voltage supply terminal coupled to the transistor and an output coupled to the driver input.

3. The circuit according to claim 2, wherein the thermal sensor circuit comprises: A temperature-proportional PTAT current source, coupled to the power device via a substrate, is configured to provide a bias signal to the control input of the control circuit in response to the temperature of the substrate.

4. The circuit of claim 3, wherein the transistor is a first transistor, the control circuit includes a second transistor having an input configured to receive the bias signal, the transistor having a voltage input coupled to the voltage supply terminal, and the second transistor having a control output coupled to the driver input.

5. The circuit of claim 3, wherein the PTAT current source is configured to provide a hysterically varying current in response to the temperature of the substrate, and The control circuit is configured to adjust the temperature of the power device according to a duty cycle in response to the current from the PTAT current source.

6. The circuit of claim 1, wherein the sensing circuit comprises: A voltage sensor having a voltage input and an output, wherein the voltage input of the voltage sensor is coupled to a first voltage terminal and a second voltage terminal; A single-trigger circuit having an input and an output, wherein the output of the voltage sensor is coupled to the input of the single-trigger circuit, and the output of the single-trigger circuit is coupled to the input of the driver.

7. The circuit of claim 6, wherein the single trigger circuit is configured to modulate the driver input in response to a voltage sensor signal at the output of the voltage sensor.

8. The circuit of claim 1, wherein the circuit is implemented as an integrated circuit, the integrated circuit including a substrate, and the power device and the sensing circuit are implemented on the substrate.

9. The circuit of claim 1, wherein the power device comprises: A first field-effect transistor (FET) has a first gate, a first source, and a first drain, wherein the first drain of the first field-effect transistor is coupled to the first voltage terminal. and The second field-effect transistor has a second gate, a second source, and a second drain. The first source of the first field-effect transistor is coupled to the second source of the second field-effect transistor, and the second drain of the second field-effect transistor is coupled to the second voltage terminal.

10. The circuit of claim 1, further comprising: Resistor; and A voltage source, which is coupled in series with the resistor between the first voltage terminal and the second voltage terminal of the power device.

11. A circuit for controlling the temperature of a power device, comprising: A power device having a first voltage terminal and a second voltage terminal and a command input, the power device being configured to conduct current between the first voltage terminal and the second voltage terminal in response to a control input signal; A thermal sensor configured to sense the temperature of the power device and provide a sensor signal in response to the sensed temperature exceeding a temperature threshold; A driver circuit configured to provide a drive signal to the command input of the power device in response to the sensor signal to conduct current and reduce the temperature of the power device, wherein the driver circuit does not include a clamping circuit system; and A transistor coupled between a first voltage terminal and a power supply terminal of the driver circuit, the transistor having a control terminal coupled to the second voltage terminal, wherein the transistor is configured to provide an input voltage from the first voltage terminal to the power supply terminal of the driver circuit in response to a voltage potential at the second voltage terminal.

12. The circuit of claim 11, wherein the power device comprises: A field-effect transistor (FET) has a first voltage terminal and a second voltage terminal as the drain and source of the FET, respectively. The FET has a body diode between the source and the drain. The FET is configured to conduct reverse current through the body diode in response to a voltage potential between the drain and the source exceeding the breakdown voltage of the FET.

13. The circuit of claim 12, wherein the thermal sensor comprises: A PTAT current source proportional to absolute temperature is coupled to the power device, the PTAT current source being configured to conduct current in response to the temperature of the power device.

14. The circuit of claim 13, wherein the transistor is a first transistor, and the thermal sensor includes a second transistor configured to control the driver circuit in response to the current.

15. The circuit of claim 14, wherein the PTAT current source is configured to provide a hysteresis-varying current in response to the temperature of the power device.

16. The circuit of claim 12, wherein the circuit is implemented as an integrated circuit including a substrate, and the power device and the thermal sensor are implemented on the substrate of the integrated circuit.

17. The circuit of claim 11, further comprising a test system configured to provide a test voltage to the first voltage terminal and the second voltage terminal during a test interval, the test voltage exceeding the breakdown voltage of the power device.

18. The circuit of claim 17, wherein the thermal sensor is configured to provide a sensor signal in a duty cycle in response to the sensed temperature to control the power device to conduct current during the test interval.

19. A system for controlling the temperature of a power device, comprising: An integrated circuit (IC) having a first voltage terminal and a second voltage terminal, the IC comprising: A power device having an input terminal and a command input, wherein the input terminal of the power device is coupled to the first voltage terminal and the second voltage terminal of the IC; A sensor coupled to the power device, the sensor being configured to provide a sensor signal in response to detecting an overload event of the power device; A driver circuit coupled to the command input of the power device and configured to activate the power device to conduct current in response to the sensor signal, wherein the driver circuit does not include a clamping circuit system; and A transistor coupled between a first voltage terminal and a power supply terminal of the driver circuit, the transistor having a control terminal coupled to the second voltage terminal, wherein the transistor is configured to provide an input voltage from the first voltage terminal to the power supply terminal of the driver circuit in response to a voltage potential at the second voltage terminal; A test system includes a voltage source coupled to the first voltage terminal and the second voltage terminal, the voltage source being configured to provide a test voltage to the first voltage terminal and the second voltage terminal to induce the overload event of the power device.

20. The system of claim 19, wherein the driver circuit is configured to supply a drive signal to the command input of the power device, the drive signal having a duty cycle during the overload event.

21. The system of claim 20, wherein the overload event includes at least one of temperature or overvoltage conditions.

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