Slow start control circuit of MOS (Metal Oxide Semiconductor) tube and power electronic equipment

Abstract

The utility model discloses a slow start control circuit of an MOS (Metal Oxide Semiconductor) tube and power electronic equipment, relates to the technical field of H-bridge circuits, and solves the technical problems that the start process of the MOS tube is not stable enough and the current state cannot be monitored and fed back in real time. The circuit comprises an enable circuit, a slow start circuit, a current detection circuit and a controller U3. The enable circuit, the slow start circuit and the current detection circuit are all connected with the controller U3, and the controller U3 is used for outputting level signals and PWM pulses with different duty ratios; the enabling circuit is connected with the power supply VCC and the slow start circuit, so that the slow start circuit and the power supply VCC are connected or disconnected; the slow start circuit is connected with the H-bridge circuit, so that the H-bridge circuit is disconnected or slow start is carried out based on PWM pulses with different duty ratios; and the current detection circuit is connected with the H-bridge circuit and is used for detecting the current output to the load by the H-bridge circuit. According to the utility model, the PWM pulse duty ratio is gradually changed, so that the starting process of the MOS tube is stable, and the safety, the reliability and the working efficiency are improved.

Description

Technical Field

[0001] This utility model relates to the field of H-bridge circuit technology, and in particular to a soft-start control circuit for a MOSFET and a power electronic device. Background Technology

[0002] MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors) are widely used power semiconductor devices in power electronics technology, offering advantages such as high switching speed, low on-resistance, and ease of driving. MOSFETs play a crucial role in various power electronic devices, such as switching power supplies, motor drivers, inverters, and uninterruptible power supplies (UPS).

[0003] In many power electronic systems, especially in H-bridge circuits built with MOSFETs, the startup process is a crucial step. However, traditional startup methods suffer from problems such as instantaneous current surges, unstable startup, and a lack of real-time protection. Instantaneous current surges: When power is suddenly switched on, the MOSFETs immediately turn on, potentially generating large instantaneous current surges, leading to voltage fluctuations and even damage to circuit components. Unstable startup: Existing startup control schemes often use simple delays or fixed duty cycles, failing to precisely control current changes during startup. This can result in large current fluctuations during startup, affecting normal system operation. Lack of real-time protection: If the current status cannot be monitored and fed back in a timely manner during startup and operation, overcurrent events can damage the system.

[0004] Existing technologies often lack effective real-time current detection and protection mechanisms. Inappropriate startup control strategies increase unnecessary energy loss and reduce overall efficiency. This is especially true in high-frequency switching applications, where energy loss during startup is significant. Some existing solutions involve using simple delay circuits or fixed duty cycle PWM signals to control the MOSFET's on-time. However, these methods are still insufficient; simple delays or fixed duty cycle methods cannot achieve precise control over current changes, resulting in an uneven startup process and the inability to monitor and provide real-time current status feedback. Therefore, there is an urgent need for a MOSFET soft-start control circuit that can achieve smooth startup and provide real-time current protection.

[0005] In the process of developing this utility model, the applicant discovered at least the following problems in the prior art:

[0006] The inability to precisely control the changes in conduction current by using delay or fixed duty cycle results in an unstable startup process for the MOSFET and an inability to monitor and provide feedback on the current status in real time. Utility Model Content

[0007] The purpose of this invention is to provide a soft-start control circuit for a MOSFET, thereby solving the technical problems in the prior art where delay or fixed duty cycle cannot accurately control changes in conduction current, resulting in an unstable MOSFET startup process and the inability to monitor and provide real-time feedback of current status. The various technical effects of the preferred solutions provided by this invention are detailed below.

[0008] To achieve the above objectives, the present invention provides the following technical solution:

[0009] This utility model provides a soft-start control circuit for a MOSFET, including an enable circuit, a soft-start circuit, a current detection circuit, and a controller U3. The enable circuit, soft-start circuit, and current detection circuit are all connected to the controller U3, which outputs a level signal and PWM pulses with different duty cycles. The enable circuit is connected to the power supply VCC and the soft-start circuit, enabling the soft-start circuit to be switched on or off from the power supply VCC. The soft-start circuit is connected to an H-bridge circuit, enabling the H-bridge circuit to be switched off or to perform a soft start based on PWM pulses with different duty cycles. The current detection circuit is connected to the H-bridge circuit and is used to detect the magnitude of the current output from the H-bridge circuit to the load.

[0010] Preferably, the enabling circuit includes a P-type MOSFET Q1 and an NPN transistor Q4; the source of the MOSFET Q1 is connected to the power supply VCC, the gate is connected to the collector of the transistor Q4, and the drain is connected to the soft-start circuit and the H-bridge circuit; the base of the transistor Q4 is connected to pin 1 of the controller U3, and the emitter is grounded.

[0011] Preferably, the enabling circuit further includes resistors R1 and R2, which divide the voltage by a proportional resistance value to enable the MOSFET Q1 to conduct normally; one end of resistor R1 is connected to the power supply VCC and the source of the MOSFET Q1, and the other end is connected to the gate of the MOSFET Q1 and the resistor R2; the two ends of resistor R2 are respectively connected to the gate of the MOSFET Q1 and the collector of the transistor Q4.

[0012] Preferably, the enabling circuit further includes resistors R3 and R4, which are used to limit the base current of transistor Q4; the two ends of resistor R3 are connected to pin 1 of controller U3 and the base of transistor Q4 respectively; one end of resistor R4 is connected to resistor R3 and the base of transistor Q4, and the other end is grounded.

[0013] Preferably, the soft-start circuit includes an N-type MOSFET Q7 and an NPN transistor Q8; the source of the MOSFET Q7 is grounded, the drain is connected to the H-bridge circuit, and the gate is connected to the collector of the MOSFET Q8 and the enable circuit; the base of the transistor Q8 is connected to pin 2 of the controller U3 to receive PWM pulses with different duty cycles output by the controller U3, the emitter is grounded, and the collector is connected to the gate of the MOSFET Q7 and the enable circuit.

[0014] Preferably, the soft-start circuit further includes resistors R5, R7, and R11, which form a voltage divider circuit to keep the source and gate voltage difference of the MOSFET Q7 stable. One end of resistor R5 is connected to the enable circuit, and the other end is connected to resistor R7 and the collector of the transistor Q8. One end of resistor R7 is connected to resistor R5 and the collector of the transistor Q8, and the other end is connected to resistor R11 and the gate of the MOSFET Q8. One end of resistor R11 is connected to resistor R7 and the gate of the MOSFET Q8, and the other end is grounded.

[0015] Preferably, the soft-start circuit further includes resistors R6, R8, and R10. Resistor R6 is used to prevent the base of transistor Q8 from breaking down. Resistor R8 is the base current-limiting resistor of transistor Q8. Resistor R10 is used to prevent the base and emitter of transistor Q8 from conducting. One end of resistor R6 is connected to the enable circuit, and the other end is connected to resistors R8 and R10 and the base of transistor Q8. One end of resistor R8 is connected to pin 2 of controller U3, and the other end is connected to resistors R6 and R10 and the base of transistor Q8. One end of resistor R10 is connected to resistors R6 and R8 and the base of transistor Q8, and the other end is grounded.

[0016] Preferably, the current detection circuit includes a current detection resistor R13 and a comparator U2; the two ends of the current detection resistor R13 are respectively connected to the H-bridge circuit and the load; the positive terminal of the comparator U2 is connected to the current detection resistor R13, the negative terminal is connected to the reference voltage VREF, and the output terminal is connected to pin 3 of the controller U3.

[0017] Preferably, the soft-start control circuit further includes a drive circuit, which is connected to the controller U3 and the H-bridge circuit, and generates four drive signals for the H-bridge circuit based on the pin level type of the controller U3.

[0018] A power electronic device, the power electronic device comprising a soft-start control circuit for a MOSFET as described in any one of the above claims.

[0019] Implementing one of the above-described technical solutions of this utility model has the following advantages or beneficial effects:

[0020] This invention achieves a gradual increase in current in the soft-start circuit by progressively changing the duty cycle of the PWM pulses output by the controller U3, making the MOSFET startup process more stable. Combined with the current signal detected by the current detection circuit, it realizes real-time monitoring and feedback of the current status. When the current is abnormal, the power supply to the soft-start control circuit is shut off in time through the enable circuit, providing real-time protection and improving the safety, reliability and working efficiency of the MOSFET in the soft-start control circuit. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. In the drawings:

[0022] Figure 1 This is a circuit diagram of a MOS transistor soft-start control circuit according to Embodiment 1 of this utility model. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this utility model clearer, various exemplary embodiments described below will be referenced to the accompanying drawings, which form part of the exemplary embodiments, illustrating various exemplary embodiments that may be adopted to implement this utility model. Unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this disclosure. It should be understood that they are merely examples of processes, methods, and apparatuses consistent with some aspects of this utility model disclosed as detailed in the appended claims, and other embodiments may be used, or structural and functional modifications may be made to the embodiments listed herein without departing from the scope and spirit of this utility model.

[0024] In the description of this utility model, it should be understood that the terms "center," "longitudinal," "lateral," etc., indicate the orientation or positional relationship based on the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the referred element must have a specific orientation, or be constructed and operated in a specific orientation. The terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. The term "multiple" means two or more. The terms "connected" and "linked" should be interpreted broadly, for example, they can be fixed connections, detachable connections, integral connections, mechanical connections, electrical connections, communication connections, direct connections, indirect connections through an intermediate medium, and can be the internal connection of two elements or the interaction relationship between two elements. The term "and / or" includes any and all combinations of one or more of the related listed items. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0025] To illustrate the technical solution described in this utility model, specific embodiments are described below, showing only the parts related to the embodiments of this utility model.

[0026] Example 1:

[0027] like Figure 1As shown, this utility model provides a soft-start control circuit for a MOSFET, including an enable circuit, a soft-start circuit, a current detection circuit, and a controller U3. The enable circuit, the soft-start circuit, and the current detection circuit are all connected to the controller U3. The controller U3 is used to output level signals and PWM (Pulse Width Modulation) pulses with different duty cycles. The duration of the PWM pulses output by the controller U3 is designed according to the settling time of the load motor in the actual application, so that the load motor can enter a stable working process after being buffered by the PWM wave, thereby avoiding damage to the MOSFET caused by excessive inrush current at the moment of startup. The enable circuit is connected to the power supply VCC and the soft-start circuit, enabling the soft-start circuit to be turned on or off from the power supply VCC. The soft-start circuit is connected to the H-bridge circuit, enabling the H-bridge circuit to be turned off or to perform soft start based on PWM pulses with different duty cycles. The smaller the duty cycle of the PWM wave output by the controller U3, that is, the smaller the proportion of the high-level time in one cycle to the entire cycle time, the longer the conduction time of the soft-start circuit, the more the H-bridge circuit is connected, the larger the current flowing in the cycle, and the lower the duty cycle, the more the current gradually increases, thus achieving the effect of soft start. The current detection circuit is connected to the H-bridge circuit to detect the current output from the H-bridge circuit (the H-bridge circuit includes interconnected N-type MOSFETs Q2, Q3, Q5, and Q6; the direction and magnitude of the load current can be controlled by controlling the four MOSFETs) to the load (in this embodiment, the load motor U1). This invention achieves a gradual increase in current in the soft-start circuit by progressively changing the duty cycle of the PWM pulses output by the controller U3, making the MOSFET startup process more stable. Combined with the current signal detected by the current detection circuit, it realizes real-time monitoring and feedback of the current status. When the current is abnormal, the power supply to the soft-start control circuit is shut off in time through the enable circuit, providing real-time protection and improving the safety, reliability and working efficiency of the MOSFET in the soft-start control circuit.

[0028] As an optional implementation method, such as Figure 1As shown, the enable circuit includes a P-type MOSFET Q1 and an NPN transistor Q4; the source of MOSFET Q1 is connected to the power supply VCC, the gate is connected to the collector of transistor Q4, and the drain is connected to the soft-start circuit (specifically, resistors R5 and R6 of the soft-start circuit) and the H-bridge circuit (specifically, MOSFETs Q2 and Q3 of the H-bridge circuit); the base of transistor Q4 is connected to pin 1 of controller U3, and the emitter is grounded. The enabling circuit also includes resistors R1 and R2. Resistors R1 and R2 divide the voltage by their resistance values ​​to enable the MOSFET Q1 to conduct normally. Specifically, resistor R1 is the voltage divider resistor between the source and gate of the MOSFET Q1. Resistors R1 and R2 divide the voltage by their resistance values ​​to ensure that the voltage difference between the source and gate of the MOSFET Q1 is 0-10V, thereby ensuring the normal conduction of the MOSFET Q1. One end of resistor R1 is connected to the power supply VCC and the source of the MOSFET Q1, and the other end is connected to the gate of the MOSFET Q1 and resistor R2. The two ends of resistor R2 are connected to the gate of the MOSFET Q1 and the collector of the transistor Q4, respectively. The enable circuit also includes resistors R3 and R4. Resistors R3 and R4 are used to limit the base current of transistor Q4 to prevent the MOSFET Q4 from being damaged by overcurrent. The two ends of resistor R3 are connected to pin 1 of controller U3 and the base of transistor Q4, respectively. One end of resistor R4 is connected to resistor R3 and the base of transistor Q4, and the other end is grounded.

[0029] As an optional implementation method, such as Figure 1As shown, the soft-start circuit includes an N-type MOSFET Q7 and an NPN transistor Q8. The source of MOSFET Q7 is grounded, its drain is connected to the H-bridge circuit, and its gate is connected to the collector and enable circuit of MOSFET Q8. The base of transistor Q8 is connected to pin 2 of controller U3 to receive PWM pulses with different duty cycles output by controller U3. Its emitter is grounded, and its collector is connected to the gate and enable circuit of MOSFET Q7. The soft-start circuit also includes resistors R5, R7, and R11, which form a voltage divider circuit to ensure that the voltage between the source and gate of MOSFET Q7 is stable at around 10V, keeping the voltage difference between the source and gate of MOSFET Q7 stable. At the same time, resistor R11 prevents the source and gate of MOSFET Q7 from being mis-converted. One end of resistor R5 is connected to the enable circuit, and the other end is connected to resistor R7 and the collector of transistor Q8; one end of resistor R7 is connected to resistor R5 and the collector of transistor Q8, and the other end is connected to resistor R11 and the gate of MOSFET Q8; one end of resistor R11 is connected to resistor R7 and the gate of MOSFET Q8, and the other end is grounded. The soft-start circuit also includes resistors R6, R8, and R10. Resistor R6 is used to prevent the base of transistor Q8 from breaking down, resistor R8 is the base current limiting resistor of transistor Q8, and resistor R10 is used to prevent the base and emitter of transistor Q8 from conducting. One end of resistor R6 is connected to the enable circuit, and the other end is connected to resistors R8 and R10 and the base of transistor Q8. One end of resistor R8 is connected to pin 2 of controller U3, and the other end is connected to resistors R6 and R10 and the base of transistor Q8. One end of resistor R10 is connected to resistors R6 and R8 and the base of transistor Q8, and the other end is grounded.

[0030] As an optional implementation method, such as Figure 1 As shown, the current detection circuit includes a current sensing resistor R13 (preferably with a resistance in the milliohm range to ensure current detection accuracy) and a comparator U2. The two ends of the current sensing resistor R13 are connected to the H-bridge circuit and the load, respectively. The positive terminal of the comparator U2 is connected to the current sensing resistor R13, and the negative terminal is connected to the reference voltage VREF (the reference voltage VREF is set as needed, determined by the current flowing through the MOSFET and the resistance value of the current sensing resistor R13). The output terminal is connected to pin 3 of the controller U3, allowing the controller to generate corresponding control signals based on the output level signal. When the soft-start control circuit is working normally, when current flows through the load U1, a voltage drop is generated across the current sensing resistor R13. If this voltage is less than the reference voltage VREF, the comparator U2 outputs a low level; if the voltage is greater than the reference voltage, the comparator U2 outputs a high level. A capacitor C1 is also connected in parallel with the current sensing resistor R13 to maintain the stability of the sampling voltage. The comparator's power supply voltage is preferably 10V. The current detection circuit also includes a pull-up resistor R12 connected to the positive power supply terminal and the output terminal of the comparator.

[0031] As an optional implementation method, such as Figure 1 As shown, the soft-start control circuit also includes a drive circuit, which is connected to the controller U3 and the H-bridge circuit. Based on the pin level type of the controller U3, four drive signals for the H-bridge circuit are generated. The four drive signals are G2, G5, G3, and G6, which are connected to the gates of MOSFETs Q2, Q3, Q5, and Q6 in the H-bridge circuit, respectively, to realize the control of the H-bridge circuit.

[0032] The working principle of this embodiment is as follows: ① In the initial state, pin 1 of controller U3 outputs a low level, transistor Q4 is not turned on, and the gate of MOSFET Q1 is disconnected from the ground, i.e., MOSFET Q1 is not turned on, the enable circuit is turned off, and the power supply VCC is disconnected from the overall circuit. ② In the normal working state, pin 1 of controller U3 outputs a high level, transistor Q4 is turned on, and the gate of MOSFET Q1 is connected to the ground. A voltage difference between the gate voltage and the emitter voltage is formed through the voltage divider network of R1 and R2, i.e., Q1 is turned on, the enable circuit is turned on, and the power supply VCC is connected to the overall circuit for power supply. At this time, the current output from the H-bridge circuit to the load increases, but the sampling voltage at the positive input of comparator U2 is still less than the reference voltage VREF at the negative input. The output of comparator U2 is low. After receiving the low-level feedback signal at pin 3 of controller U3, the control drive signals G2, G5, G3, and G6 are output. At this time, pin 1 of the controller outputs a high level, ensuring that the overall circuit is continuously in the conducting state. ③ When an overcurrent occurs in the circuit, the current output from the H-bridge circuit to the load increases until the sampling voltage at the positive input of U2 is greater than the reference voltage VREF at the negative input. U2 outputs a high level. After receiving a high-level feedback signal, pin 3 of U3 controls drive signals G2, G5, G3, and G6 to a low level, and pin 1 of the controller outputs a low level, ensuring the circuit remains in the off state until the current returns to normal. Then, pin 3 of the controller U3 receives a low-level feedback signal, which in turn controls drive signals G2, G5, G3, and G6 to output, causing pin 1 of the controller U3 to output a high level, thus restarting the circuit. ④ During circuit startup, pin 1 of the controller U3 outputs a high level, transistor Q4 conducts, and the gate of MOSFET Q1 is connected to the ground. A voltage divider network of resistors R1 and R2 forms a voltage difference between the gate and emitter, causing MOSFET Q1 to conduct, enabling the circuit. Power supply VCC is then connected to the circuit for power. At startup, the controller U3 outputs a PWM pulse, and within this pulse, the duty cycle gradually decreases. When pin 2 of controller U3 outputs a high level, transistor Q8 conducts, power supply VCC is grounded through resistor R5, MOSFET Q7 does not conduct, the H-bridge is disconnected from the ground, the load motor current loop is incomplete, the voltage reference point is lost, and no current flows through the load motor U1. When pin 2 of controller U3 outputs a low level, transistor Q8 does not conduct, power supply VCC supplies power to the gate of MOSFET Q7 through resistors R5 and R7, MOSFET Q7 conducts, the H-bridge is connected to the ground, and the circuit conducts normally. ⑤ During the soft start process, if the current reaches the overcurrent protection value at a certain PWM pulse, the overcurrent protection is triggered, and pin 1 of controller U3 outputs a low level to ensure that the circuit remains in the off state until the current returns to normal. Then, pin 3 of controller U3 receives a low-level feedback signal, which controls the output of drive signals G2, G5, G3, and G6, and pin 1 outputs a high level, restarting the circuit and enhancing the overall circuit safety.

[0033] The embodiment is merely a special case and does not indicate that this utility model is implemented in such a way.

[0034] Example 2:

[0035] A power electronic device includes a soft-start control circuit for a MOSFET as described in Embodiment 1. By employing the soft-start control circuit of Embodiment 1, the safety and stability of the power electronic device are improved.

[0036] The above description is merely a preferred embodiment of the present utility model. Those skilled in the art will understand that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of the present utility model. Furthermore, under the teachings of the present utility model, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of the present utility model. Therefore, the present utility model is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the protection scope of the present utility model.

Claims

1. A slow start control circuit for a MOS transistor, characterized by comprising: The application relates to a power supply circuit, which comprises an enabling circuit, a slow start circuit, a current detection circuit and a controller U3; the enabling circuit, the slow start circuit and the current detection circuit are connected with the controller U3, the controller U3 is used for outputting a level signal and a PWM pulse with different duty cycles; the enabling circuit is connected with a power supply VCC and the slow start circuit, so that the slow start circuit is turned on or turned off with the power supply VCC; the slow start circuit is connected with an H-bridge circuit, so that the H-bridge circuit is turned off or slowly started based on the PWM pulse with different duty cycles; and the current detection circuit is connected with the H-bridge circuit and used for detecting the current size of the H-bridge circuit output to a load. The enabling circuit comprises a P-type MOS tube Q1 and an NPN-type triode Q4; the source of the MOS tube Q1 is connected with the power supply VCC, the gate is connected with the collector of the triode Q4, and the drain is connected with the slow start circuit and the H-bridge circuit; the base of the triode Q4 is connected with a pin 1 of the controller U3, and the emitter is grounded.

2. The soft-start control circuit of a MOS transistor according to claim 1, wherein, The enabling circuit further comprises resistors R1 and R2; the resistors R1 and R2 are used for proportionally dividing the voltage to enable the MOS tube Q1 to be normally turned on; one end of the resistor R1 is connected with the power supply VCC and the source of the MOS tube Q1, and the other end is connected with the gate of the MOS tube Q1 and the resistor R2; and the two ends of the resistor R2 are respectively connected with the gate of the MOS tube Q1 and the collector of the triode Q4.

3. The soft-start control circuit for a MOS transistor of claim 2, wherein, The enabling circuit further comprises resistors R3 and R4; the resistors R3 and R4 are used for limiting the base current of the triode Q4; the two ends of the resistor R3 are respectively connected with the pin 1 of the controller U3 and the base of the triode Q4; one end of the resistor R4 is connected with the resistor R3 and the base of the triode Q4, and the other end is grounded.

4. The soft-start control circuit for a MOS transistor of claim 2, wherein, The slow start circuit comprises an N-type MOS tube Q7 and an NPN-type triode Q8; the source of the MOS tube Q7 is grounded, the drain is connected with the H-bridge circuit, and the gate is connected with the collector of the MOS tube Q8 and the enabling circuit; the base of the triode Q8 is connected with a pin 2 of the controller U3 and used for receiving the PWM pulse with different duty cycles output by the controller U3, the emitter is grounded, and the collector is connected with the gate of the MOS tube Q7 and the enabling circuit.

5. The soft-start control circuit for a MOSFET of claim 1, wherein, The slow start circuit further comprises resistors R5, R7 and R11; the resistors R5, R7 and R11 form a voltage dividing circuit, so that the voltage difference between the source and the gate of the MOS tube Q7 is kept stable; one end of the resistor R5 is connected with the enabling circuit, and the other end is connected with the resistor R7 and the collector of the triode Q8; one end of the resistor R7 is connected with the resistor R5 and the collector of the triode Q8, and the other end is connected with the resistor R11 and the gate of the MOS tube Q8; one end of the resistor R11 is connected with the resistor R7 and the gate of the MOS tube Q8, and the other end is grounded.

6. The soft-start control circuit for a MOS transistor of claim 5, wherein, ​ 7. The circuit of claim 5, wherein the circuit further comprises a first capacitor coupled between the first node and the second node. The slow start circuit further comprises a resistor R6 for preventing the base of the triode Q8 from being broken down, a resistor R8 as the base current limiting resistor of the triode Q8, and a resistor R10 for preventing the base and emitter of the triode Q8 from being turned on; one end of the resistor R6 is connected with the enable circuit, and the other end is connected with the resistor R8, the resistor R10, and the base of the triode Q8; one end of the resistor R8 is connected with the pin 2 of the controller U3, and the other end is connected with the resistor R6, the resistor R10, and the base of the triode Q8; one end of the resistor R10 is connected with the resistor R6, the resistor R8, and the base of the triode Q8, and the other end is grounded.

8. A soft-start control circuit for a MOS transistor as defined in any one of claims 1, characterized in that The current detection circuit comprises a current detection resistor R13 and a comparator U2; two ends of the current detection resistor R13 are respectively connected with the H-bridge circuit and the load; the positive electrode of the comparator U2 is connected with the current detection resistor R13, the negative electrode is connected with a reference voltage VREF, and the output end is connected with the pin 3 of the controller U3.

9. A soft-start control circuit for a MOS transistor as claimed in any one of claims 1 to 8, wherein, The slow start control circuit further comprises a drive circuit connected with the controller U3 and the H-bridge circuit, and generating four drive signals of the H-bridge circuit based on the pin level type of the controller U3.

10. A power electronic device, characterized by The power electronic device comprises the MOS tube slow start control circuit according to any one of claims 1-9.

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