Single-point detection device and method for safe working area of power MOSFET

Abstract

The invention provides a single-point detection device and method for a safe working area of a power MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor), and relates to the technical field of semiconductor device testing. The single-point detection device comprises a pulse trigger circuit, a sampling feedback circuit, a driving amplification circuit, a capacitance energy storage circuit and a data collector. The pulse trigger circuit is used for outputting a pulse signal with a preset width according to the conduction time corresponding to the specific test point; the sampling feedback circuit is used for collecting the drain current of the power MOSFET and generating a feedback signal; the driving amplification circuit drives the power MOSFET to be switched on or switched off according to the feedback signal and the pulse signal; the capacitance energy storage circuit provides target drain-source voltage for the power MOSFET according to the drain-source voltage corresponding to the specific test point; and the data collector records the waveforms of the drain-source voltage and the drain current of the power MOSFET. The single-point detection device does not need to add extra lines, parameter matching is achieved by adjusting devices in the single-point detection device, the test efficiency is improved, and the single-point detection device has the advantages of being efficient, flexible, high in precision and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor device testing, and in particular to a single-point detection device and method for a power MOSFET safe operating area. Background Art

[0002] As an important semiconductor device, power metal oxide semiconductor field-effect transistors (MOSFETs) are widely used in high-power applications such as switching power supplies, motor drives, and new energy vehicle electronic control systems due to their excellent switching performance and power handling capabilities. In power MOSFET applications, the safe operating area (SOA) is a core metric that measures the MOSFET's ability to operate reliably under extreme voltage (VDS), current (Id), and time conditions. Accurate SOA assessment is crucial to ensuring the safety, stability, and reliability of power MOSFETs in practical applications.

[0003] However, traditional MOSFET SOA test methods have numerous limitations. Common SOA test methods currently include direct measurement, oscilloscope multiplication, and case temperature measurement. While these methods can provide a safe operating area assessment to a certain extent, they present numerous challenges in practical applications. First, test efficiency is low. Traditional methods typically use DC or long pulse signals, which significantly increase device temperature, prolonging test time and potentially damaging the device. Second, equipment compatibility is poor. High-voltage and low-voltage testing often require different equipment, making it impossible to cover the full range of power MOSFET specifications with a single platform, increasing test cost and complexity. Furthermore, adjustment accuracy is insufficient. Adjusting the on-time of gate-source voltage VGS and drain current ID relies on the coordinated operation of multiple instruments, which is not only complex but also prone to introducing errors, affecting the accuracy of test results. Finally, quality control lags. SOA testing is typically concentrated in the back-end of finished product production. Traditional methods require multiple high-voltage and low-voltage instruments, making widespread adoption in the front-end production difficult due to high testing costs.

[0004] In summary, traditional MOSFET SOA test methods cannot effectively identify early failure risks during the selection and incoming material inspection stages, which may lead to batch quality accidents. In addition, single-point testing has limitations such as low data acquisition efficiency, long test cycles, and poor environmental adaptability, and it is difficult to accurately test single-point SOA. Therefore, traditional MOSFET SOA test methods cannot meet the high-precision, high-efficiency, and high-compatibility requirements of power MOSFET SOA evaluation in high-power applications.

[0005] In order to meet the requirements of high efficiency, flexibility and high precision for single-point detection of power MOSFET SOA, the industry urgently needs to develop a single-point detection device and method for the safe operating area of ​​power MOSFET. Summary of the Invention

[0006] As mentioned above, the traditional MOSFET SOA test method has limitations in single-point testing, such as low data acquisition efficiency, long test cycle, and poor environmental adaptability, and it is difficult to accurately test single-point SOA.

[0007] This application proposes a single-point detection device for a power MOSFET safe operating area, comprising: A pulse trigger circuit is used to output a pulse signal of a preset width according to the conduction time corresponding to a specific test point in the safe operating area curve; A sampling feedback circuit, connected to the power MOSFET, for collecting the drain current of the power MOSFET and generating a feedback signal; a driving amplifier circuit, connected to the pulse trigger circuit and the sampling feedback circuit, and configured to drive the power MOSFET to be turned on or off according to the pulse signal and the feedback signal; a capacitor energy storage circuit connected between the drain and source of the power MOSFET and configured to provide a target drain-source voltage to the power MOSFET according to a drain-source voltage corresponding to a specific test point in the safe operating area curve; and A data collector is used to record the waveform of the drain-source voltage and the waveform of the drain current of the power MOSFET, wherein the waveform of the drain-source voltage and / or the waveform of the drain current of the power MOSFET is used to determine whether the power MOSFET has failed.

[0008] Optionally, the pulse trigger circuit includes: an adjustable voltage generating circuit, configured to receive a DC voltage and generate an adjustable voltage signal according to a conduction time corresponding to a specific test point in the safe operating area curve; and A timer is connected to the adjustable voltage generating circuit and is used to generate the pulse signal according to the adjustable voltage signal.

[0009] Optionally, the adjustable voltage generating circuit includes: a first adjustable resistor, wherein a first end of the first adjustable resistor is configured to receive the DC voltage; and A first capacitor, wherein a first end of the first capacitor is connected to the second end of the first adjustable resistor and is used to provide the adjustable voltage signal, and a second end of the first capacitor is grounded.

[0010] Optionally, a position of a sliding end of the first adjustable resistor is adjusted according to a conduction time corresponding to a specific test point in the safe operating area curve to adjust a resistance value of the first adjustable resistor, and the preset width is adjusted according to the resistance value of the first adjustable resistor and a capacitance value of the first capacitor.

[0011] Optionally, the preset width is 1.1 × vr1 × c1, where vr1 is the resistance value of the first adjustable resistor, and c1 is the capacitance value of the first capacitor.

[0012] Optionally, the pulse trigger circuit further comprises: a first resistor, a first end of the first resistor being configured to receive the direct current voltage; and a key, a first end of the key being connected to a second end of the first resistor and the timer respectively, and a second end of the key being grounded; wherein the timer is triggered when the key is closed.

[0013] Optionally, the driving amplification circuit comprises: a first switch tube, a first end of the first switch tube being configured to receive a direct current voltage, and a control end of the first switch tube being connected to the pulse trigger circuit to receive the pulse signal; a second switch tube, a first end of the second switch tube being grounded, a second end of the second switch tube being connected to a second end of the first switch tube, and a control end of the second switch tube being connected to the control end of the first switch tube; a first diode, a cathode of the first diode being connected to the second end of the first switch tube; a second diode, an anode of the second diode being connected to the first end of the first switch tube; a third switch tube, a first end of the third switch tube being connected to a cathode of the second diode, and a control end of the third switch tube being connected to an anode of the first diode; and a fourth switch tube, a first end of the fourth switch tube being grounded, a second end of the fourth switch tube being connected to a second end of the third switch tube and a control end of the power MOSFET respectively, and a control end of the fourth switch tube being connected to the control end of the third switch tube.

[0014] Optionally, the sampling feedback circuit is further configured to set a target drain current according to a drain current corresponding to a specific test point in the safe operating area curve.

[0015] Optionally, the sampling feedback circuit comprises: a second resistor, a first end of the second resistor being configured to receive the direct current voltage; a second adjustable resistor, a first end of the second adjustable resistor is connected to a second end of the second resistor, and a second end of the second adjustable resistor is grounded; a reference source, a first end of the reference source is connected to a reference end of the reference source and the first end of the second adjustable resistor respectively, and a second end of the reference source is grounded; a sampling resistor, a first end of the sampling resistor is connected to the source of the power MOSFET, and a second end of the sampling resistor is grounded, the sampling resistor is used to collect the drain current of the power MOSFET and generate a sampling signal; and a comparator, a first input end of the comparator is connected to the first end of the sampling resistor for receiving the sampling signal, a second input end of the comparator is connected to the wiper of the second adjustable resistor for receiving an adjustable reference voltage, and an output end of the comparator is connected to the control end of the fourth switch tube for outputting the feedback signal.

[0016] Optionally, the position of the wiper of the second adjustable resistor is adjusted according to the drain current corresponding to a specific test point in the safe operating area curve to adjust the adjustable reference voltage.

[0017] Optionally, when the sampling signal is greater than the adjustable reference voltage, the drive amplification circuit drives the power MOSFET to be turned off according to the feedback signal.

[0018] Optionally, the capacitor energy storage circuit comprises: a double-pole double-throw switch, a first input end of the double-pole double-throw switch is connected to a charging DC source, and a second input end of the double-pole double-throw switch is connected to ground through a discharge resistor, a high-voltage capacitor, a first end of the high-voltage capacitor is connected to a first output end and a fourth output end of the double-pole double-throw switch, and a second end of the high-voltage capacitor is grounded; a low-voltage capacitor, a first end of the low-voltage capacitor is connected to a second output end and a third output end of the double-pole double-throw switch, and a second end of the low-voltage capacitor is grounded; and a switch, connected between the first end of the high-voltage capacitor and the drain of the power MOSFET, for turning on during testing.

[0019] Preferably, the double-pole double-throw switch is controlled according to the drain-source voltage corresponding to a specific test point in the safe operating area curve, so that the charging DC source charges one of the high-voltage capacitor and the low-voltage capacitor to the target drain-source voltage, and the other of the high-voltage capacitor and the low-voltage capacitor is discharged through the discharge resistor.

[0020] The application also proposes a single-point detection method for a safe operating area of a power MOSFET, comprising: output a preset width pulse signal according to the on-time corresponding to the specific test point in the safe operating area curve; collecting drain current of the power MOSFET and generating a feedback signal; driving the power MOSFET to turn on or off according to the pulse signal and the feedback signal; providing a target drain-source voltage to the power MOSFET according to the drain-source voltage corresponding to the specific test point in the safe operating area curve; recording the waveform of the drain-source voltage and the waveform of the drain current of the power MOSFET, wherein the waveform of the drain-source voltage and / or the waveform of the drain current of the power MOSFET are used to determine whether the power MOSFET is failed.

[0021] Preferably, the waveform of the drain-source voltage and / or the waveform of the drain current of the power MOSFET are used to determine whether the power MOSFET is failed, comprising: determining whether the maximum value of the drain current in the waveform of the drain current of the power MOSFET exceeds the drain current corresponding to the specific test point in the safe operating area curve, if yes, marking as failed, if no, marking as passed.

[0022] Preferably, the target drain current is provided according to the drain current corresponding to the specific test point in the safe operating area curve.

[0023] The beneficial effects of the present application at least include: The single-point detection device for the safe operating area of ​​a power MOSFET in this embodiment includes a pulse trigger circuit, a sampling feedback circuit, a drive amplifier circuit, a capacitor energy storage circuit, and a data collector. The pulse trigger circuit is configured to output a pulse signal of a preset width based on the on-time corresponding to a specific test point in the safe operating area curve; the sampling feedback circuit is configured to collect the drain current of the power MOSFET and generate a feedback signal; the drive amplifier circuit is configured to drive the power MOSFET on or off based on the pulse signal and the feedback signal; the capacitor energy storage circuit is configured to provide a target drain-source voltage to the power MOSFET based on the drain-source voltage corresponding to the specific test point in the safe operating area curve; and the data collector is configured to record the waveform of the drain-source voltage and the waveform of the drain current of the power MOSFET, wherein the waveform of the drain-source voltage and / or the waveform of the drain current of the power MOSFET is used to determine whether the power MOSFET has failed. This single-point detection device can apply high voltage and high current to the power MOSFET within the conduction time of a single pulse signal (for example, microseconds) without damaging the device, thereby realizing single-point testing of SOA. This device does not require additional circuits and costs, improves test efficiency, and has the advantages of high efficiency, flexibility and high precision. It can realize fast, accurate and efficient evaluation of the safe operating area of ​​the power MOSFET, thereby improving the reliability and quality control level of the power MOSFET in high-power applications.

[0024] The capacitor energy storage circuit includes a double-pole double-throw switch, a high-voltage capacitor, a discharge resistor, and a low-voltage capacitor. By controlling the double-pole double-throw switch, a charging DC source charges one of the high-voltage and low-voltage capacitors to the target drain-source voltage, and the other one discharges through the discharge resistor. This single-point detection device has a wide range of applications and is compatible with both high-voltage and low-voltage testing requirements.

[0025] The above has generally summarized the features and technical advantages of the present application so that the following detailed description of the application can be better understood. The additional features and advantages of the present application will be described below, which form the subject matter of the claims of the present application. It will be understood by those skilled in the art that the disclosed concepts and specific embodiments can be easily utilized as the basis for modifying or designing other structures or processes for achieving the same purpose of the present application. It will also be appreciated by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the present application as set forth in the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] For a more complete understanding of the present application and its advantages, reference is now made to the following description in conjunction with the accompanying drawings, in which: Figure 1 A schematic diagram showing the structure of a single-point detection device for a power MOSFET safe operating area according to an embodiment of the present application is shown; Figure 2A circuit diagram showing the internal structure of a single-point detection device for a power MOSFET safe operating area according to an embodiment of the present application is shown; Figure 3 A schematic diagram showing a safe operating area curve according to an embodiment of the present application is shown; Figure 4 The following diagram shows a voltage waveform and a current waveform detected when the drain-source voltage is 40V and the drain current is 8A at a specific test point in the safe operating area curve according to an embodiment of the present application; Figure 5 The following diagram shows a voltage waveform and a current waveform detected when the drain-source voltage is 80V and the drain current is 4A at a specific test point in the safe operating area curve according to an embodiment of the present application; Figure 6 A flow chart of a single-point detection method for a power MOSFET safe operating area according to an embodiment of the present application is shown.

[0027] Corresponding numerals and symbols in the different figures generally refer to corresponding parts unless otherwise indicated.The figures are drawn to clearly illustrate the relevant aspects of the various embodiments and are not necessarily drawn to scale. DETAILED DESCRIPTION

[0028] Various exemplary embodiments, features, and aspects of the present invention will be described in detail below with reference to the accompanying drawings. The same reference numerals in the accompanying drawings represent elements with the same or similar functions. Although various aspects of the embodiments are shown in the accompanying drawings, the drawings are not necessarily drawn to scale unless otherwise indicated.

[0029] The word "exemplary" is used exclusively herein to mean "serving as an example, example, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments. The terms "first," "second," "third," and so on (if any) in the description and claims of the present invention and in the drawings are used to distinguish similar items and are not necessarily used to describe a particular order or sequential sequence.

[0030] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "coupled," "connected," and "connected" should be understood broadly. For example, they may refer to electrical connection or mutual communication, direct connection or indirect connection through an intermediary, internal communication between two components, or interaction between two components. Those skilled in the art will understand the specific meanings of these terms in the present invention based on specific circumstances.

[0031] In addition, numerous specific details are provided in the following detailed description to better illustrate the present invention. Those skilled in the art will appreciate that the present invention can be practiced without certain specific details. In some instances, methods, means, components, and circuits well known to those skilled in the art have not been described in detail in order to highlight the main points of the present invention.

[0032] See also Figure 1 A structural schematic diagram of a single-point detection device for the safe operating area of ​​a power MOSFET according to an embodiment of the present application is shown. The embodiment of the present application provides a single-point detection device for the safe operating area of ​​a power MOSFET, which is used to accurately test a single point in the safe operating area curve of the power MOSFET QT under test, wherein the safe operating area curve can refer to the specification sheet of the power MOSFET under test. Specifically, according to the specification sheet of the power MOSFET under test, a specific test point in the safe operating area (SOA) curve is selected for accurate testing, wherein the selected specific test point will include parameters such as the drain-source voltage Vds, the drain current Id, and the on-time t. The single-point detection device for the safe operating area of ​​a power MOSFET includes: a pulse trigger circuit 11, a sampling feedback circuit 13, a drive amplifier circuit 12, a capacitor energy storage circuit 14, and a data collector 15. The pulse trigger circuit 11 is used to receive a DC voltage VCC and output a preset width according to the on-time t corresponding to the specific test point in the SOA curve. The pulse signal is such that the preset width is equal to or approximately equal to the on-time t. In this embodiment, the pulse signal may be a single pulse signal.

[0033] The sampling feedback circuit 13 is connected to the power MOSFET QT and is used to collect the drain current Id of the power MOSFET and generate a feedback signal. Specifically, the sampling feedback circuit 13 is used to set a target drain current based on the drain current Id corresponding to a specific test point in the SOA curve, and to generate the feedback signal based on the target drain current and the collected drain current of the power MOSFET QT.

[0034] The driving amplifier circuit 12 is connected to the pulse trigger circuit 11 and the sampling feedback circuit 13, and is used to drive the power MOSFET QT to be turned on or off according to the pulse signal and the feedback signal.

[0035] The capacitor energy storage circuit 14 is connected between the drain and the source of the power MOSFET QT, and is configured to provide a target drain-source voltage to the power MOSFET QT according to the drain-source voltage Vds corresponding to a specific test point in the safe operating area curve. The capacitor energy storage circuit 14 provides instantaneous high-power output to the power MOSFET QT, so that the drain-source voltage between the drain and the source of the power MOSFET QT is the target drain-source voltage.

[0036] The data collector 15 is configured to record the waveform of the drain-source voltage and the waveform of the drain current of the power MOSFET QT, wherein the waveform of the drain-source voltage and / or the waveform of the drain current of the power MOSFET QT are used to determine whether the power MOSFET QT is failed. In the embodiment, the data collector 15 can be an oscilloscope, and the oscilloscope is connected to the power MOSFET QT through a differential probe and a current probe, so as to record the waveform of the drain-source voltage and the waveform of the drain current of the power MOSFET QT.

[0037] For the characteristics of high voltage, large current and fast switching of the power MOSFET, the single-point detection device for the safe operating area of the power MOSFET provided by the application has the advantages of high efficiency, flexibility, high precision and the like, and can realize fast, accurate and efficient evaluation of the safe operating area of the power MOSFET, and accurate testing of specific test points in the SOC curve, so as to improve the reliability and quality control level of the power MOSFET in high-power applications. In the test of the power MOSFET, the power MOSFET is turned on by a single pulse signal to avoid overheating of the power MOSFET. The detection device can be tested independently from product application, supports front-end selection and incoming inspection of the power MOSFET, identifies failure risks in advance, has a simple structure, relies less on external equipment, reduces cost, and has strong practicality.

[0038] The sampling feedback circuit 13 is configured to collect the drain current Id of the power MOSFET and generate a feedback signal to form a current feedback protection mechanism to effectively protect the power MOSFET.

[0039] Please refer to Figure 1 and Figure 2 The pulse trigger circuit 11 includes an adjustable voltage generating circuit and a timer. The adjustable voltage generating circuit is configured to receive a direct current voltage VCC and generate an adjustable voltage signal according to the turn-on time t corresponding to a specific test point in the safe operating area curve. The timer is connected to the adjustable voltage generating circuit and is configured to generate the pulse signal according to the adjustable voltage signal, wherein the pulse signal has a preset width .

[0040] Furthermore, the adjustable voltage generating circuit includes a first adjustable resistor VR1 and a first capacitor C1. The first end of the first adjustable resistor VR1 is used to receive the DC voltage VCC, and the sliding end of the first adjustable resistor VR1 is connected to the first end of the first adjustable resistor VR1. The first end of the first capacitor C1 is connected to the second end of the first adjustable resistor VR1 for providing the adjustable voltage signal, and the second end of the first capacitor is grounded. In this embodiment, the first adjustable resistor VR1 and the first capacitor C1 are connected in series to form an RC network, and the connection between the first adjustable resistor VR1 and the first capacitor C1 is used to provide the adjustable voltage signal.

[0041] Furthermore, the position of the sliding end of the first adjustable resistor VR1 is adjusted according to the on-time t corresponding to the specific test point in the safe operating area curve to adjust the resistance of the first adjustable resistor VR1, and the preset width is adjusted according to the resistance of the first adjustable resistor VR1 and the capacitance of the first capacitor C1.

[0042] Furthermore, the preset width Approximately 1.1 × vr1 × c1, where vr1 is the resistance of the first adjustable resistor VR1, and c1 is the capacitance of the first capacitor C1.

[0043] Furthermore, the timer may be a 555 timer including pins 1 to 8. A first pin GND of the 555 timer is grounded, a fourth pin RST and an eighth pin VCC of the 555 timer are used to receive the DC voltage VCC, a fifth pin CTRL of the 555 timer is grounded via a second capacitor C2, a seventh pin DIS and a sixth pin TIIR of the 555 timer are connected to the first end of the first capacitor C1 for receiving the adjustable voltage signal, and a third pin OUT of the 555 timer is used to output the pulse signal.

[0044] Furthermore, the pulse trigger circuit 11 also includes a first resistor R1 and a button S1. The first end of the first resistor R1 is configured to receive the DC voltage VCC. The first end of the button S1 is connected to the second end of the first resistor S1 and the second pin TRIG of the 555 timer, respectively. The second end of the button S1 is grounded. The connection between the first resistor R1 and the button S1 is configured to provide a trigger signal to the 555 timer. When the button is closed, the potential of the second pin TRIG of the 555 timer is pulled low, thereby triggering the 555 timer.

[0045] By adjusting the position of the sliding end of the first adjustable resistor VR1 to adjust the resistance value of the first adjustable resistor VR1, the preset width of the single pulse is Equal or close to the conduction time t corresponding to the specific test point in the SOA curve. It can be seen that by adjusting the first adjustable resistor VR1, the preset width of the pulse signal can be accurately set .

[0046] Further, the driving amplification circuit 12 comprises a first switch tube Q1, a second switch tube Q2, a third switch tube Q3, a fourth switch tube Q4, a first diode D1 and a second diode D2. The first end of the first switch tube Q1 is used to receive the direct current voltage VCC, the control end of the first switch tube Q1 is connected with the output end of the pulse trigger circuit, for example, a timer, for receiving the pulse signal. The first end of the second switch tube Q2 is grounded, the second end of the second switch tube Q2 is connected with the second end of the first switch tube Q1, and the control end of the second switch tube Q2 is connected with the control end of the first switch tube Q1. The cathode of the first diode D1 is connected with the second end of the first switch tube Q1. The anode of the second diode D2 is connected with the first end of the first switch tube Q1. The first end of the third switch tube Q3 is connected with the cathode of the second diode D2, and the control end of the third switch tube Q3 is connected with the anode of the first diode D1. The first end of the fourth switch tube Q4 is grounded, the second end of the fourth switch tube Q4 is connected with the second end of the third switch tube Q3, and the second end of the third switch tube Q3 is connected with the control end of the power MOSFET QT through the resistance R4, and the control end of the fourth switch tube Q4 is connected with the control end of the third switch tube Q3.

[0047] Specifically, the driving amplification circuit 12 includes two totem pole amplification circuits, wherein the first switch tube Q1 and the second switch tube Q2 constitute a first stage totem pole, and the third switch tube Q3 and the fourth switch tube Q4 constitute a second stage totem pole. When the pulse signal output by the timer is at a high level, the first switch tube Q1 and the third switch tube Q3 are controlled to be turned on, and the pulse signal output by the timer passes through the first switch tube Q1, the second diode D2 and the third switch tube Q3 to drive the power MOSFET QT to be turned on, wherein the second end of the third switch tube Q3 provides a high-level driving voltage and driving current of an approximate direct current voltage VCC, improves the current driving capability, and ensures that the power MOSFET is completely turned on. When the pulse signal output by the timer is at a low level, the second switch tube Q2 and the fourth switch tube Q4 are controlled to be turned on, and the reverse electromotive force generated by the gate inductance is discharged through the fourth switch tube Q4, the first diode D1 and the second switch tube Q2 to drive the power MOSFET QT to be turned off, so as to ensure that the power MOSFET is turned off more thoroughly. The first diode D1 can limit the gate-source voltage of the power MOSFET QT in the range of -0.7V to the direct current voltage VCC, and at the same time, when the pulse signal output by the timer is at a low level, the fourth switch tube Q4 and the second switch tube Q2 are connected in communication to quickly absorb the reverse electromotive force generated by the gate inductance, so as to prevent the negative breakdown of the gate oxide layer. The first diode D1 and the second diode D2 are driven to be anti-interference.

[0048] Further, the sampling feedback circuit 13 comprises a second resistor R2, a second adjustable resistor VR2, a reference source U3, a sampling resistor RS and a comparator U2. The first end of the second resistor R2 is connected to receive the DC power supply VCC. The first end of the second adjustable resistor VR2 is connected to the second end of the second resistor R2, and the second end of the second adjustable resistor VR2 is grounded. The first end (e.g. cathode) of the reference source U3 is connected to the reference terminal of the reference source U3 and the first end of the second adjustable resistor VR2 respectively, and the second end (e.g. anode) of the reference source U3 is grounded. The first end of the sampling resistor RS is connected to the source of the power MOSFET QT, and the second end of the sampling resistor RS is grounded. The sampling resistor RS is used to collect the drain current of the power MOSFET QT and generate a sampling signal. The second resistor R2 and the reference source U3 are connected in series, and a reference voltage, for example 2.5V, is output at the connection point between the second resistor R2 and the reference source U3. The reference voltage is divided by adjusting the position of the sliding end of the second adjustable resistor VR2 to obtain an adjustable reference voltage. The first input terminal of the comparator U2 is connected to the first end of the sampling resistor RS through a resistor R5 to receive the sampling signal, and the first input terminal of the comparator U2 is connected to the output terminal of the comparator U2 through a third capacitor C3. The second input terminal of the comparator U2 is connected to the sliding end of the second adjustable resistor VR2 to receive the adjustable reference voltage Vth, and the output terminal of the comparator U2 is connected to the control terminal of the fourth switch tube Q4 through a resistor R3 to output the feedback signal.

[0049] Further, when the sampling signal is greater than the adjustable reference voltage Vth, the drive amplification circuit 12 drives the power MOSFET to be turned off according to the feedback signal, thereby playing a role of current feedback protection. Specifically, the comparator U2 compares the sampling signal and the adjustable reference voltage Vth. When the sampling signal is greater than the adjustable reference voltage Vth, the comparator U2 outputs a low level, so that the fourth switch tube Q4 is turned on, and the power MOSFET gate is discharged through the fourth switch tube Q4 until it is lower than the turn-on threshold, so that the power MOSFET QT is turned off. In this embodiment, the second diode D2 ensures that the output terminal of the comparator U2 is unidirectionally pulled low to drive the power MOSFET QT to be turned off.

[0050] Further, the position of the sliding terminal of the second adjustable resistor VR2 is adjusted according to the drain current of the specific test point on the safe operating area curve to adjust the adjustable reference voltage Vth, and the target drain current is set according to the adjustable reference voltage Vth and the resistance of the sampling resistor RS. Specifically, the sampling signal is obtained according to the drain current Id of the specific test point on the safe operating area curve and the resistance of the sampling resistor RS, where the sampling signal is the product of the drain current Id of the specific test point on the safe operating area curve and the resistance of the sampling resistor RS, and the adjustable reference voltage Vth is obtained by adjusting the sliding terminal of the second adjustable resistor VR2. Similarly, when the adjustable reference voltage Vth is obtained, the target drain current of the power MOSFET can be obtained in reverse, which is the quotient of the adjustable reference voltage Vth and the sampling resistor RS. By adjusting the second adjustable resistor VR2, the target drain current of the power MOSFET QT can be accurately set.

[0051] Further, the capacitor energy storage circuit 14 includes a double-pole double-throw switch S3, a high-voltage capacitor C4, a low-voltage capacitor C4, and a switch S2. The first input terminal of the double-pole double-throw switch S3 is connected to the charging DC source Vcharge, and the second input terminal of the double-pole double-throw S3 is connected to ground through a discharge resistor RL. The first terminal of the high-voltage capacitor C4 is connected to the first output terminal and the fourth output terminal of the double-pole double-throw S3, and the second terminal of the high-voltage capacitor C4 is connected to ground. The first terminal of the low-voltage capacitor C5 is connected to the second output terminal and the third output terminal of the double-pole double-throw S3, and the second terminal of the low-voltage capacitor C5 is connected to ground. The switch S2 is connected between the first terminal of the high-voltage capacitor C4 and the drain of the power MOSFET QT. In this embodiment, the high-voltage capacitor C4 can be composed of a plurality of high-voltage electrolytic capacitors in series and parallel connection to support the testing of high-voltage power MOSFETs, and the low-voltage capacitor C5 can be composed of a plurality of low-voltage capacitors in parallel connection to support low-voltage power MOSFETs. In this embodiment, the high-voltage capacitor C4 is used to provide a first target drain-source voltage to the power MOSFET, and the low-voltage capacitor C5 is used to provide a second target drain-source voltage to the power MOSFET.

[0052] Further, the double-pole double-throw switch is controlled according to the drain-source voltage of the specific test point on the safe operating area curve, so that the charging DC source charges one of the high-voltage capacitor and the low-voltage capacitor to the target drain-source voltage, and the other of the high-voltage capacitor and the low-voltage capacitor is discharged through the discharge resistor.

[0053] Specifically, when the drain-source voltage corresponding to the test point in the SOA curve is high voltage, the high-voltage capacitor C4 stores energy by charging the DC power supply Vcharge, that is, the voltage of the DC power supply Vcharge is adjusted to the first target drain-source voltage according to the drain-source voltage corresponding to the test point in the SOA curve, and then the high-voltage capacitor C4 is charged to the target drain-source voltage by the DC power supply Vcharge, while the low-voltage capacitor C5 is discharged through the discharge resistor RL. In this embodiment, the first target drain-source voltage is equal to or close to the drain-source voltage corresponding to the test point in the SOA curve. When the test starts, the switch S2 is turned on, so that the high-voltage capacitor C4 supplies power to the power MOSFET. When the power MOSFET is turned on, the high-voltage capacitor C4 is discharged through the power MOSFET and the sampling resistor RS, generating the required drain-source voltage and drain current for the test. When the test is completed, the switch S2 is turned off, and the double-pole double-throw switch S3 is switched, so that the high-voltage capacitor C4 releases energy through the discharge resistor RL.

[0054] When the drain-source voltage corresponding to the test point in the SOA curve is low voltage, the low-voltage capacitor C5 stores energy by charging the DC power supply Vcharge, that is, the voltage of the DC power supply Vcharge is adjusted to the second target drain-source voltage according to the drain-source voltage corresponding to the test point in the SOA curve, and then the low-voltage capacitor C5 is charged to the target drain-source voltage by the DC power supply Vcharge, while the high-voltage capacitor C4 is discharged through the discharge resistor RL. In this embodiment, the second target drain-source voltage is equal to or close to the drain-source voltage corresponding to the test point in the SOA curve. When the test starts, the switch S2 is turned on, so that the low-voltage capacitor C5 supplies power to the power MOSFET. When the power MOSFET is turned on, the low-voltage capacitor C5 is discharged through the power MOSFET and the sampling resistor RS, generating the required drain-source voltage and drain current for the test. When the test is completed, the switch S2 is turned off, and the double-pole double-throw switch S3 is switched, so that the low-voltage capacitor C5 releases energy through the discharge resistor RL.

[0055] The single-point detection device of the safe working area of the power MOSFET in this embodiment can meet the test requirements of high voltage (for example, 650V) and low voltage (for example, 40V).

[0056] The energy storage energy of the capacitor is calculated by the following formula: .

[0057] The maximum discharge current can be calculated by the formula: .

[0058] wherein, is the energy storage energy of the capacitor, is the capacitance of the capacitor, is the charging voltage provided by the DC power supply, is the resistance of the loop resistance, where the loop resistance includes the on-resistance RDS(on) of the power MOSFET and the sampling resistor RS.

[0059] In this embodiment, if the capacitance of the high-voltage capacitor C4 is 6800μF, the drain-source voltage Vds of the power MOSFET is 700V, the drain current Id of the power MOSFET is 80A, the on-resistance RDS(on) of the power MOSFET is 1.5Ω, the resistance of the sampling resistor RS is 50mΩ, the line resistance R=Rs+RDS(on)=1.55Ω, and the preset width of the pulse signal is For 10ms, when the high-voltage capacitor C4 is charged to 700V, the stored energy is: , the maximum discharge current is , the maximum value of this discharge current is greater than the measured drain current of the power MOSFET.

[0060] If the low-voltage capacitor C5 has a capacity of 160000μF, the drain-source voltage Vds of the power MOSFET is 40V, the drain current Id of the power MOSFET is 190A, the on-resistance RDS(on) of the power MOSFET is 38mΩ, the resistance of the sampling resistor RS is 10mΩ, the line resistance R=Rs+RDS(on)=48mΩ, the preset width of the pulse signal When the low-voltage capacitor C5 is charged to 40V, the stored energy is: , the maximum discharge current is , the maximum value of this discharge current is greater than the measured drain current of the power MOSFET.

[0061] Due to the difference in physical structure, the drift region of high voltage MOS is designed to be thicker, the on-resistance RDS(on) is larger, and the gate-drain capacitance Cgd is higher. According to the formula It can be seen that at the moment when the high-voltage or low-voltage MOS is turned on, the energy of the capacitor is sufficient to support the high power output required for short-time pulse testing.

[0062] During the test, the pulse trigger circuit 11 outputs a single pulse signal to control the power MOSFET to turn on, and the high-voltage capacitor or the low-voltage capacitor is quickly discharged through the power MOSFET and the sampling resistor RS, forming a transient large drain current and drain-source voltage, simulating the SOA extreme working condition.

[0063] The discharge process is divided into two phases: initial and decay. In the initial phase, the high-voltage or low-voltage capacitor is rapidly released through the power MOSFET and sampling resistor RS, generating a peak current. In the decay phase, the high-voltage or low-voltage capacitor decreases with discharge time, and the current decays exponentially.

[0064] The peak current calculation formula is: .

[0065] The formula for current decay over time is: , in is the time constant, .

[0066] The capacitor voltage decay formula is: .

[0067] To meet SOA test requirements, it is necessary to ensure the preset width of the pulse signal Less than the time constant , so that the voltage of the high-voltage capacitor or the low-voltage capacitor is approximately constant during the test, and the current remains stable. .

[0068] In this embodiment, the capacitance of the high voltage capacitor is , loop resistance The resistance is 1.55Ω, so the time constant is for .

[0069] When the preset width of the pulse signal When the power MOSFET is tested, the drain-source voltage Vds and drain current Id are approximately constant instantaneously during the test.

[0070] The following test is based on two specific test points on the SOA curve of a 500V / 5A power MOSFET with a turn-on time t of 1ms. The corresponding drain-source voltages at the two test points are 40V and 80V, and the corresponding drain currents are 8A and 4A, respectively.

[0071] Test the first specific test point (drain-source voltage is 40V, drain current is 8A), such as Figure 2 、 Figure 3 and Figure 4As shown, the double-pole double-throw switch is controlled to operate so that the low-voltage capacitor C5 is connected to the charging DC source Vcharge, and the voltage of the charging DC source is 40V at this time. A capacitor with a capacitance of 100nF is selected as the first capacitor C1, and the resistance of the first adjustable resistor VR1 is calculated by the conduction time t and the first capacitor C1, so that the resistance of the first adjustable resistor is approximately 0.9kΩ. According to the first capacitor and the first adjustable resistor, a pulse signal of a preset width can be output, wherein the preset width tpulse=1.1×0.9kΩ×100nF≈1ms. The second adjustable resistor VR2 is adjusted to set the target drain current, and the sampling resistor RS is taken as 0.05Ω. The second adjustable resistor is adjusted so that the adjustable reference voltage Vth=0.4V. At this time, the target drain current is obtained according to the sampling resistor and the adjustable reference voltage, and the target drain current Imax=0.4 / 0.05=8A. As shown Figure 4 As shown, the first waveform is the drain-source voltage waveform of the power MOSFET, and the second waveform is the drain current waveform of the power MOSFET. The maximum current value in the waveform of the drain current of the power MOSFET is 8A, reaching the drain current corresponding to the first specific test point in the SOA curve, and the power MOSFET does not break down, so it is judged to have passed.

[0072] The second specific test point (drain-source voltage is 80V, drain current is 4A) is tested, as shown in the following example: Figure 2 、 Figure 3 and Figure 5 As shown, the double-pole double-throw switch is controlled to operate so that the high-voltage capacitor C4 is connected to the charging DC source Vcharge, and the voltage of the charging DC source is 80V at this time. A capacitor with a capacitance of 100nF is selected as the first capacitor C1, and the resistance of the first adjustable resistor VR1 is calculated by the conduction time t and the first capacitor C1, so that the resistance of the first adjustable resistor is approximately 0.9kΩ. According to the first capacitor and the first adjustable resistor, a pulse signal of a preset width can be output, wherein the preset width tpulse=1.1×0.9kΩ×100nF≈1ms. The second adjustable resistor VR2 is adjusted to set the target drain current, and the sampling resistor RS is taken as 0.05Ω. The second adjustable resistor is adjusted so that the adjustable reference voltage Vth=0.2V. At this time, the target drain current is obtained according to the sampling resistor and the adjustable reference voltage, and the target drain current Imax=0.2 / 0.05=4A. As shown Figure 5 As shown, the first waveform is the drain-source voltage waveform of the power MOSFET, and the second waveform is the drain current waveform of the power MOSFET. The maximum current value in the waveform of the drain current of the power MOSFET is 4A, reaching the drain current corresponding to the second specific test point in the SOA curve, and the power MOSFET still does not break down, so it is judged to have passed.

[0073] In this embodiment, the first specific test point or the second specific test point is tested, and the maximum current value in the waveform of the drain current of the power MOSFET obtained exceeds the drain current corresponding to the first specific test point or the second specific test point, and the power MOSFET breaks down and is judged to be failed.

[0074] In other embodiments, testing the first specific test point or the second specific test point can be used to determine whether the MOSFET has failed based on the waveform of the drain-source voltage of the power MOSFET, or can be used to determine whether the MOSFET has failed based on the waveform of the drain-source voltage of the power MOSFET and the waveform of the drain current of the power MOSFET.

[0075] In view of the high voltage, high current and fast switching characteristics of power MOSFET, the single-point detection device for the safe operating area of ​​power MOSFET provided by the present application adjusts the resistance value of the first adjustable resistor according to the conduction time corresponding to the specific test point in the SOA curve to output a pulse signal of a preset width, and adjusts the second adjustable resistor according to the drain current corresponding to the specific test point in the SOA curve so that the drain current of the power MOSFET reaches the target drain current, and then provides the power MOSFET with a target drain-source voltage according to the drain-source voltage corresponding to the specific test point in the SOA curve, thereby achieving the ability to accurately set the preset width of the pulse signal, the target drain-source voltage and the target drain current. It has the advantages of high efficiency, flexibility and high precision, and can achieve fast, accurate and efficient evaluation of the safe operating area of ​​the power MOSFET, as well as precise testing of specific test points in the SOC curve, so as to improve the reliability and quality control level of the power MOSFET in high-power applications. When testing the power MOSFET, the power MOSFET is driven to conduct by a single pulse signal to prevent the power MOSFET from overheating. The detection device can be used for single-unit testing independent of product applications, supports front-end selection and incoming material inspection of power MOSFET units, and identifies failure risks in advance. It also has a simple structure, relies less on external equipment, reduces costs, and is highly practical.

[0076] like Figure 6 As shown, the embodiment of the present application also provides a single-point detection method for a power MOSFET safety zone, including: Step S11: outputting a pulse signal of a preset width according to the on-time corresponding to a specific test point in the safe operating area curve; Step S12: collecting the drain current of the power MOSFET and generating a feedback signal; Step S13: driving the power MOSFET to be turned on or off according to the pulse signal and the feedback signal; Step S14: providing a target drain-source voltage to the power MOSFET according to the drain-source voltage corresponding to a specific test point in the safe operating area curve; Step S15: recording the drain-source voltage waveform and the drain current waveform of the power MOSFET, wherein the drain-source voltage waveform and / or the drain current waveform of the power MOSFET are used to determine whether the power MOSFET has failed.

[0077] Specifically, such as Figure 1 As shown, the pulse trigger circuit 11 is used to receive the DC voltage VCC and output a pulse signal of a preset width according to the conduction time t corresponding to a specific test point in the SOA curve, so that the preset width is equal to or approximately equal to the conduction time t. In this embodiment, the pulse signal can be a single pulse signal.

[0078] The sampling feedback circuit 13 is connected to the power MOSFET QT and is used to collect the drain current Id of the power MOSFET and generate a feedback signal. Specifically, the sampling feedback circuit 13 is used to set a target drain current based on the drain current Id corresponding to a specific test point in the SOA curve, and to generate the feedback signal based on the target drain current and the collected drain current of the power MOSFET QT.

[0079] The driving amplifier circuit 12 is connected to the pulse trigger circuit 11 and the sampling feedback circuit 13, and is used to drive the power MOSFET QT to be turned on or off according to the pulse signal and the feedback signal.

[0080] A capacitor tank circuit 14 is connected between the drain and source of the power MOSFET QT and is configured to provide a target drain-source voltage to the power MOSFET QT based on the drain-source voltage Vds corresponding to a specific test point in the safe operating area curve. The capacitor tank circuit 14 provides instantaneous high power output to the power MOSFET QT, such that the drain-source voltage between the drain and source of the power MOSFET QT reaches the target drain-source voltage.

[0081] The data collector 15 is configured to record the waveform of the drain-source voltage and the waveform of the drain current of the power MOSFET QT. The waveform of the drain-source voltage and / or the waveform of the drain current of the power MOSFET QT is used to determine whether the power MOSFET QT has failed. In this embodiment, the data collector 15 may be an oscilloscope, which is configured to record the waveform of the drain-source voltage and the waveform of the drain current of the power MOSFET QT by connecting the oscilloscope's differential probe and current probe to the power MOSFET QT.

[0082] Furthermore, the waveform of the drain-source voltage and / or the waveform of the drain current of the power MOSFET is used to determine whether the power MOSFET has failed, including: Determine whether the maximum value of the drain current in the waveform of the drain current of the power MOSFET exceeds the drain current corresponding to the specific test point in the safe operating area curve. If so, mark it as failed; otherwise, mark it as passed.

[0083] Furthermore, a target drain current is provided according to a drain current corresponding to a specific test point in the safe operating area curve.

[0084] In view of the high voltage, high current and fast switching characteristics of power MOSFET, the single-point detection method for the safe operating area of ​​power MOSFET provided in this application can adjust the resistance of the first adjustable resistor according to the conduction time corresponding to the specific test point in the SOA curve to output a pulse signal of a preset width, and adjust the second adjustable resistor according to the drain current corresponding to the specific test point in the SOA curve so that the drain current of the power MOSFET reaches the target drain current. Then, according to the drain-source voltage corresponding to the specific test point in the SOA curve, the target drain-source voltage is provided to the power MOSFET, thereby achieving the ability to accurately set the preset width of the pulse signal, the target drain-source voltage and the target drain current. It has the advantages of high efficiency, flexibility and high precision, and can achieve rapid, accurate and efficient evaluation of the safe operating area of ​​the power MOSFET, as well as precise testing of specific test points in the SOC curve, to improve the reliability and quality control level of the power MOSFET in high-power applications. During the power MOSFET test, the power MOSFET is driven to conduct by a single pulse signal to avoid overheating of the power MOSFET. This method supports the front-end selection and incoming material inspection of power MOSFET monomers, identifies failure risks in advance, and has a simple structure, less reliance on external equipment, reduces costs and is highly practical.

[0085] Although the embodiments of the present application and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the application as defined by the appended claims.

[0086] Furthermore, the scope of this application is not limited to the particular embodiments of the processes, machines, manufactures, compositions of matter, means, methods, and steps described in this specification. Those skilled in the art will readily appreciate from the disclosure of this application that, in accordance with this application, currently existing or later developed processes, machines, manufactures, compositions of matter, means, methods, or steps may be utilized that perform substantially the same functions or achieve substantially the same results as the corresponding embodiments described herein. Accordingly, it is intended that the appended claims include within their scope such processes, machines, manufactures, compositions of matter, means, methods, or steps.

Claims

1. A single-point detection device for a power MOSFET safe operating area, characterized in that: include: A pulse trigger circuit is used to output a pulse signal of a preset width according to the conduction time corresponding to a specific test point in the safe operating area curve; A sampling feedback circuit, connected to the power MOSFET, for collecting the drain current of the power MOSFET and generating a feedback signal; a driving amplifier circuit, connected to the pulse trigger circuit and the sampling feedback circuit, and configured to drive the power MOSFET to be turned on or off according to the pulse signal and the feedback signal; a capacitor energy storage circuit connected between the drain and source of the power MOSFET and configured to provide a target drain-source voltage to the power MOSFET according to the drain-source voltage corresponding to a specific test point in the safe operating area curve; as well as A data collector is used to record the waveform of the drain-source voltage and the waveform of the drain current of the power MOSFET, wherein the waveform of the drain-source voltage and / or the waveform of the drain current of the power MOSFET is used to determine whether the power MOSFET has failed.

2. The single-point detection device for the safe operating area of ​​a power MOSFET according to claim 1, characterized in that: The pulse trigger circuit comprises: an adjustable voltage generating circuit, configured to receive a DC voltage and generate an adjustable voltage signal according to a conduction time corresponding to a specific test point in the safe operating area curve; and A timer is connected to the adjustable voltage generating circuit and is used to generate the pulse signal according to the adjustable voltage signal.

3. The single-point detection device for the safe operating area of ​​a power MOSFET according to claim 2, characterized in that: The adjustable voltage generating circuit comprises: a first adjustable resistor, a first end of the adjustable resistor being configured to receive the DC voltage; and A first capacitor, wherein a first end of the first capacitor is connected to the second end of the first adjustable resistor and is used to provide the adjustable voltage signal, and a second end of the first capacitor is grounded.

4. The single-point detection device for the safe operating area of ​​a power MOSFET according to claim 3, characterized in that: The position of the sliding end of the first adjustable resistor is adjusted according to the conduction time corresponding to a specific test point in the safe operating area curve to adjust the resistance of the first adjustable resistor, and the preset width is adjusted according to the resistance of the first adjustable resistor and the capacitance of the first capacitor.

5. The single-point detection device for the safe operating area of ​​a power MOSFET according to claim 3, characterized in that: The preset width is 1.1×vr1×c1, where vr1 is the resistance of the first adjustable resistor, and c1 is the capacitance of the first capacitor.

6. The single-point detection device for the safe operating area of ​​a power MOSFET according to claim 2, characterized in that: The pulse trigger circuit also includes: a first resistor, wherein a first end of the first resistor is configured to receive the DC voltage; and a button, wherein a first end of the button is connected to the second end of the first resistor and the timer respectively, and a second end of the button is grounded; When the button is closed, the timer is triggered.

7. The single-point detection device for the safe operating area of ​​a power MOSFET according to claim 1, characterized in that: The driving amplifier circuit includes: a first switching tube, wherein a first end of the first switching tube is used to receive a DC voltage, and a control end of the first switching tube is connected to the pulse trigger circuit, and is used to receive the pulse signal; a second switching tube, wherein a first end of the second switching tube is grounded, a second end of the second switching tube is connected to the second end of the first switching tube, and a control end of the second switching tube is connected to the control end of the first switching tube; a first diode, wherein a cathode of the first diode is connected to the second end of the first switching tube; a second diode, wherein an anode of the second diode is connected to the first end of the first switching tube; a third switching tube, wherein a first terminal of the third switching tube is connected to the cathode of the second diode, and a control terminal of the third switching tube is connected to the anode of the first diode; and A fourth switch tube, wherein a first end of the fourth switch tube is grounded, a second end of the fourth switch tube is respectively connected to the second end of the third switch tube and the control end of the power MOSFET, and the control end of the fourth switch tube is connected to the control end of the third switch tube.

8. The single-point detection device for the safe operating area of ​​a power MOSFET according to claim 7, characterized in that: The sampling feedback circuit is further configured to set a target drain current according to a drain current corresponding to a specific test point in the safe operating area curve.

9. The single-point detection device for the safe operating area of ​​a power MOSFET according to claim 8, characterized in that: The sampling feedback circuit includes: a second resistor, wherein a first end of the second resistor is used to receive the DC voltage; a second adjustable resistor, wherein a first end of the second adjustable resistor is connected to a second end of the second resistor, and the second end of the second adjustable resistor is grounded; A reference source, wherein a first end of the reference source is respectively connected to the reference end of the reference source and the first end of the second adjustable resistor, and a second end of the reference source is grounded; a sampling resistor, wherein a first end of the sampling resistor is connected to the source of the power MOSFET, a second end of the sampling resistor is grounded, and the sampling resistor is used to collect the drain current of the power MOSFET and generate a sampling signal; and A comparator, wherein a first input end of the comparator is connected to the first end of the sampling resistor for receiving the sampling signal, a second input end of the comparator is connected to the sliding end of the second adjustable resistor for receiving the adjustable reference voltage, and an output end of the comparator is connected to the control end of the fourth switching tube for outputting the feedback signal.

10. The single-point detection device for the safe operating area of ​​a power MOSFET according to claim 9, characterized in that: The position of the sliding end of the second adjustable resistor is adjusted according to the drain current corresponding to the specific test point in the safe operating area curve to adjust the adjustable reference voltage.

11. The single-point detection device for the safe operating area of ​​a power MOSFET according to claim 9, characterized in that: When the sampling signal is greater than the adjustable reference voltage, the driving amplifier circuit drives the power MOSFET to turn off according to the feedback signal.

12. The single-point detection device for the safe operating area of ​​a power MOSFET according to claim 1, characterized in that: The capacitor energy storage circuit comprises: A double-pole double-throw switch, wherein a first input terminal of the double-pole double-throw switch is connected to a charging DC source, and a second input terminal of the double-pole double-throw switch is grounded via a discharge resistor. a high-voltage capacitor, wherein a first end of the high-voltage capacitor is connected to the first output end and the fourth output end of the double-pole double-throw, and a second end of the high-voltage capacitor is grounded; a low-voltage capacitor, wherein a first end of the low-voltage capacitor is connected to the second output end and the third output end of the double-pole double-throw, and a second end of the low-voltage capacitor is grounded; and A switch is connected between the first end of the high-voltage capacitor and the drain of the power MOSFET, and is configured to be turned on during testing.

13. The single-point detection device for the safe operating area of ​​a power MOSFET according to claim 12, characterized in that: The double-pole double-throw action is controlled according to the drain-source voltage corresponding to a specific test point in the safe operating area curve, so that the charging DC source charges one of the high-voltage capacitor and the low-voltage capacitor to the target drain-source voltage, and the other of the high-voltage capacitor and the low-voltage capacitor is discharged through the discharge resistor.

14. A single-point detection method for a power MOSFET safe operating area, characterized in that: include: By outputting a pulse signal of preset width according to the conduction time corresponding to a specific test point in the safe operating area curve; Collecting the drain current of the power MOSFET and generating a feedback signal; Driving the power MOSFET on or off according to the pulse signal and the feedback signal; Providing a target drain-source voltage to the power MOSFET according to the drain-source voltage corresponding to a specific test point in the safe operating area curve; The drain-source voltage waveform and the drain current waveform of the power MOSFET are recorded, wherein the waveform of the drain-source voltage and / or the waveform of the drain current of the power MOSFET are used to determine whether the power MOSFET has failed.

15. The single-point detection method for the safe operating area of ​​a power MOSFET according to claim 14, characterized in that: The waveform of the drain-source voltage and / or the waveform of the drain current of the power MOSFET is used to determine whether the power MOSFET has failed, including: Determine whether the maximum value of the drain current in the waveform of the drain current of the power MOSFET exceeds the drain current corresponding to the specific test point in the safe operating area curve. If so, mark it as failed; otherwise, mark it as passed.

16. The single-point detection method for the safe operating area of ​​a power MOSFET according to claim 14, wherein: A target drain current is provided according to a drain current corresponding to a specific test point in the safe operating area curve.

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