A power switch tube driving circuit and method

Abstract

The present invention discloses a power switch tube driving circuit and method. When turning on the power switch tube, a charging module uses the current output by a current sequence module for charging to generate a voltage and supply it to the gate of a source follower switch. Moreover, during the charging process, the current sequence module is controlled to generate a variable charging current, so that the gate voltage of the power switch tube rapidly rises to near the turn-on threshold and then slowly rises and remains at the turn-on threshold; when it is necessary to turn off the power switch tube, a switch tube sequence module is turned on and generates a variable equivalent resistance, so that the gate voltage of the power switch tube rapidly drops to near the turn-on threshold and then slowly drops to the turn-on threshold and then rapidly drops to zero. Thus, the present invention achieves better EMI characteristics, reflects that the sampled voltage waveform has less interference, the rising and falling speeds of the drain voltage of the power switch tube are relatively smooth, and the switching delay is reduced, and the efficiency is optimized, and it has wide applicability.

Description

Technical Field

[0001] The present invention relates to the field of switching power supplies, and in particular, to a power switch tube drive circuit and method. Background Art

[0002] Existing MOS drive circuits, such as Figure 1 shown, include a drive control circuit, switching transistors M1 and M2, and a power MOS transistor M0. The drive control circuit drives the power MOS transistor M0 by controlling the opening and closing of the switching transistors M1 and M2 through switches K1 and K2.

[0003] Combined with Figure 1 , Figure 2 , Figure 2 where Vgate and VD respectively represent the gate and drain voltages of M0, and R(on)_M2 represents the equivalent resistance of M2. The conduction process of the power MOS transistor M0 is as follows: When K1 is at a low level, the switching transistor M1 conducts; when K2 is at a low level, the switching transistor M2 is cut off; the drive current flows into the source follower switch gate, and the gate of the power MOS transistor M0 is charged through the source follower switch M1; the gate voltage of the power MOS transistor rises above the turn-on threshold voltage Vt0 (Vt0 is a characteristic parameter of the power MOS transistor), and the MOS transistor quickly conducts; the drain-source current of the power MOS transistor flows through Rs, and the voltage of Rs also increases accordingly. Since the power MOS transistor M0 conducts quickly, it is easy to cause relatively large EMI interference, which is manifested as a large overshoot in the initial stage of the source voltage of the power MOS transistor M0 (Vs voltage in the figure). The turn-off process of the power MOS transistor M0 is as follows: The drive module controls K1 to be at a high level and K2 to be at a low level; the switching transistor M1 is cut off and the switching transistor M2 conducts; the gate charge of the power MOS transistor M0 is discharged to the reference ground through M2, so the gate charge of M0 quickly discharges to a low level and the power MOS transistor M0 is cut off. Since the gate charge of the power MOS transistor M0 discharges too fast, the drain voltage of the power MOS transistor M0 rises too fast with a relatively large voltage change rate (dv / dt), thus causing EMI interference. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a power switch tube drive circuit and method for the above-mentioned defect of being prone to EMI interference in the prior art.

[0005] The technical solution adopted by the present invention to solve its technical problems is as follows:

[0006] On the one hand, a power switch tube drive circuit is constructed, and the drive circuit includes:

[0007] A gate voltage detection circuit, connected to the gate of the power switch tube, for detecting the gate voltage of the power switch tube in real time;

[0008] A source follower switch, the drain of the source follower switch is connected to a power supply, and the source is connected to the gate of the power switch transistor;

[0009] A charging module and a current sequence module, the current sequence module is connected to the charging module, and the charging module is connected between the gate of the source follower switch and the ground, and is used to charge with the current output by the current sequence module to generate a voltage and provide it to the gate of the source follower switch;

[0010] A switch transistor sequence module, including a plurality of parallel-connected switch transistors, the drain of the switch transistor is connected to the gate of the power switch transistor, and the source is grounded;

[0011] A drive control circuit is respectively connected to the gate voltage detection circuit, the current sequence module, the gate of the source follower switch, and the gate of the switch transistor. When it is necessary to turn on the power switch transistor, the drive control circuit controls all the switch transistors in the switch transistor sequence module to turn off, controls the current sequence module to generate a variable charging current, so that the gate voltage of the power switch transistor rises rapidly until it is detected that the gate voltage of the power switch transistor rises close to the turn-on threshold, and then rises slowly and remains at the turn-on threshold; when it is necessary to turn off the power switch transistor, the drive control circuit controls the current output by the current sequence module to be zero so that the source follower switch turns off, controls the switch transistor sequence module to turn on and generate a variable equivalent resistance, so that the gate voltage of the power switch transistor drops rapidly until it is close to the turn-on threshold of the power switch transistor, and then drops slowly to the turn-on threshold and then drops rapidly to zero.

[0012] Preferably, the controlling the current sequence module to generate a variable charging current includes:

[0013] The first stage: controlling the current sequence module to generate a first current to rapidly raise the gate voltage of the power switch transistor until it is detected that the gate voltage of the power switch transistor rises close to the turn-on threshold and then enters the second stage;

[0014] The second stage: controlling the current sequence module to generate a second current and start timing, the second current is less than the first current so that the gate voltage of the power switch transistor rises slowly and remains at the turn-on threshold in this stage, and when the timing time reaches a first preset duration, it enters the third stage;

[0015] Third stage: Control the current sequence module to generate a third current and start timing. The third current is greater than the second current so that the gate voltage of the source follower switch rapidly rises to the limiting voltage Vclamp of the charging module. At the same time, the gate voltage of the power switch transistor rises to Vclamp - Vgs, where Vgs represents the voltage difference between the gate and the source when the source follower switch is turned on. When the timing time reaches the second preset duration, enter the fourth stage;

[0016] Fourth stage: Control the current sequence module to generate a fourth current. The fourth current is less than the third current so that the gate voltage of the source follower switch remains at the limiting voltage Vclamp.

[0017] Preferably, controlling the switch transistor sequence module to conduct and generate a variable equivalent resistance includes:

[0018] First stage: Control the equivalent resistance of the switch transistor sequence module to be a first equivalent resistance so that the gate voltage of the power switch transistor rapidly drops until it is detected that the gate voltage of the power switch transistor drops to near the turn-on threshold, then enter the second stage;

[0019] Second stage: Control the equivalent resistance of the switch transistor sequence module to be a second equivalent resistance and start timing. The second equivalent resistance is greater than the first equivalent resistance so that the gate voltage of the power switch transistor slowly drops and remains at the turn-on threshold during this stage. When the timing time reaches the third preset duration, enter the third stage;

[0020] Third stage: Control the equivalent resistance of the switch transistor sequence module to be a third equivalent resistance. The third equivalent resistance is less than the second equivalent resistance so that the gate voltage of the power switch transistor rapidly drops to zero.

[0021] Preferably, the charging module includes a clamping zener diode and a charging capacitor. The charging capacitor is connected between the gate of the source follower switch and the ground. The negative electrode of the clamping zener diode is connected to the gate of the source follower switch, and the positive electrode is grounded.

[0022] Preferably, the drive circuit further includes a pre-stage switch. The pre-stage switch is connected between the gate of the source follower switch and the ground, and the control end of the pre-stage switch is connected to the drive control circuit;

[0023] When it is necessary to turn on the power switch transistor, the drive control circuit controls the pre-stage switch to turn off so that the charging module charges using the current output by the current sequence module;

[0024] When it is necessary to turn off the power switch transistor, the drive control circuit controls the conduction of the pre-stage switch to release the charge of the charging module, so as to turn off the source follower switch.

[0025] Preferably, the current sequence module includes a plurality of current sources connected in parallel, and the switch transistor sequence module includes a plurality of MOS transistors connected in parallel.

[0026] On the other hand, the present invention also constructs a power switch transistor driving method, which is applied to the power switch transistor driving circuit as described above. The method includes:

[0027] When it is necessary to turn on the power switch transistor, the drive control circuit controls all the switch transistors of the switch transistor sequence module to turn off, and controls the current sequence module to generate a variable charging current, so that the gate voltage of the power switch transistor rises rapidly until it approaches the turn-on threshold of the power switch transistor, and then rises slowly and remains at the turn-on threshold.

[0028] When it is necessary to turn off the power switch transistor, the drive control circuit controls the current output by the current sequence module to be zero so that the source follower switch turns off, and controls the switch transistor sequence module to conduct and generate a variable equivalent resistance, so that the gate voltage of the power switch transistor drops rapidly until it approaches the turn-on threshold of the power switch transistor, then drops slowly to the turn-on threshold, and then drops rapidly to zero.

[0029] Preferably, the controlling the current sequence module to generate a variable charging current includes:

[0030] The first stage: controlling the current sequence module to generate a first current to rapidly raise the gate voltage of the power switch transistor until it is detected that the gate voltage of the power switch transistor rises to approach the turn-on threshold, and then enter the second stage;

[0031] The second stage: controlling the current sequence module to generate a second current and start timing. The second current is less than the first current, so that the gate voltage of the power switch transistor rises slowly and remains at the turn-on threshold in this stage. When the timing time reaches the first preset duration, enter the third stage;

[0032] The third stage: controlling the current sequence module to generate a third current and start timing. The third current is greater than the second current, so that the gate voltage of the source follower switch rapidly rises to the limiting voltage Vclamp of the charging module, and at the same time the gate voltage of the power switch transistor rises to Vclamp-Vgs, where Vgs represents the voltage difference between the gate and the source when the source follower switch is conducting. When the timing time reaches the second preset duration, enter the fourth stage;

[0033] Fourth stage: Control the current sequence module to generate a fourth current, where the fourth current is less than the third current so that the gate voltage of the source follower switch is maintained at the limiting voltage Vclamp.

[0034] Preferably, controlling the switch transistor sequence module to conduct and generate a variable equivalent resistance includes:

[0035] First stage: Control the equivalent resistance of the switch transistor sequence module to be a first equivalent resistance so that the gate voltage of the power switch transistor drops rapidly until it is detected that the gate voltage of the power switch transistor drops to near the turn-on threshold, and then enter the second stage;

[0036] Second stage: Control the equivalent resistance of the switch transistor sequence module to be a second equivalent resistance and start timing. The second equivalent resistance is greater than the first equivalent resistance so that the gate voltage of the power switch transistor drops slowly in this stage and remains at the turn-on threshold. When the timing time reaches the third preset duration, enter the third stage;

[0037] Third stage: Control the equivalent resistance of the switch transistor sequence module to be a third equivalent resistance, where the third equivalent resistance is less than the second equivalent resistance so that the gate voltage of the power switch transistor drops rapidly to zero.

[0038] Preferably, the method further includes: when it is necessary to turn on the power switch transistor, the drive control circuit controls the pre-stage switch to turn off so that the charging module charges using the current output by the current sequence module; when it is necessary to turn off the power switch transistor, the drive control circuit controls the pre-stage switch to turn on to release the charge of the charging module, thereby turning off the source follower switch.

[0039] The power switch transistor drive circuit and method of the present invention have the following beneficial effects: When the present invention turns on the power switch transistor, it cooperates with the current sequence module and the charging module. The charging module uses the current output by the current sequence module to charge and generate a voltage to provide to the gate of the source follower switch, and controls the current sequence module to generate a variable charging current, so that the gate voltage of the power switch transistor rises rapidly to near the turn-on threshold of the power switch transistor and then rises slowly and remains at the turn-on threshold; when it is necessary to turn off the power switch transistor, the switch transistor sequence module conducts and generates a variable equivalent resistance, so that the gate voltage of the power switch transistor drops rapidly to near the turn-on threshold of the power switch transistor, then drops slowly to the turn-on threshold, and then drops rapidly to zero. In this way, the present invention achieves good EMI characteristics, which is reflected in that the sampled voltage Vs waveform has less interference and the rising and falling speeds of the drain voltage of the power switch transistor are relatively smooth, and the switching delay is reduced and the efficiency is optimized. Therefore, it has wide applicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained according to the provided drawings:

[0041] Figure 1 is the circuit diagram of the existing power switch tube drive circuit;

[0042] Figure 2 is the waveform diagram when the existing power switch tube drive circuit works;

[0043] Figure 3 is the circuit diagram of the power switch tube drive circuit of the present invention;

[0044] Figure 4 is the waveform diagram when the power switch tube drive circuit of the present invention works. Specific embodiments

[0045] To facilitate the understanding of the present invention, the following will describe the present invention more comprehensively with reference to the relevant drawings. The typical embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive. It should be understood that the embodiments of the present invention and the specific features in the embodiments are detailed descriptions of the technical solutions of the present application, rather than limitations on the technical solutions of the present application. Without conflict, the embodiments of the present invention and the technical features in the embodiments can be combined with each other.

[0046] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0047] Embodiment 1

[0048] Reference Figure 3 , this embodiment discloses a power switch tube drive circuit for driving a power switch tube M0. The power switch tube M0 can be integrated with the chip or not. The source electrode of the power switch tube M0 can be connected to some common PCB components such as a transformer or an inductor. The source electrode of the power switch tube M0 is grounded through a sampling resistor Rs.

[0049] The driving circuit of the power switch tube M0 in this embodiment includes: a gate voltage detection circuit, a source follower switch M1, a pre-stage switch S0, a current sequence module, a charging module, a switch tube sequence module, and a driving control circuit.

[0050] The gate voltage detection circuit is connected to the gate of the power switch tube M0 and is used to detect the gate voltage of the power switch tube M0 in real time.

[0051] The source follower switch M1, the drain of the source follower switch M1 is connected to the power supply, and the source is connected to the gate of the power switch tube M0. The NMOS tube is used for the source follower switch M1 in this embodiment.

[0052] The pre-stage switch S0 is connected between the gate of the source follower switch M1 and the ground. The pre-stage switch S0 can be, but is not limited to, electronic switches such as MOS tubes and triodes.

[0053] The current sequence module can adopt multiple parallel current sources, such as m current sources. For example, K0[1:m] in the appendix represents the control signals of the m current sources. By selecting the number of current sources put into use, the charging current output by the current sequence module can be changed. Figure 3 The charging module is connected between the gate of the power switch tube M0 and the ground. The current sequence module is connected to the charging module. The charging module is used to charge by using the current output by the current sequence module to generate a voltage and supply it to the gate of the source follower switch M1. Specifically, in this embodiment, the charging module includes a clamping zener diode D0 and a charging capacitor C0. The charging capacitor C0 is connected between the gate of the source follower switch M1 and the ground. The negative electrode of the clamping zener diode D0 is connected to the gate of the source follower switch M1, and the positive electrode is grounded. It can be understood that the zener diode D0 can be in the form of multiple series-connected zener diodes to achieve a higher clamping voltage. In addition, a zener diode can be connected between the gate and the source of the source follower switch M1 to protect the source follower switch M1. The charging capacitor C0 is equivalent to the capacitor from the gate of the source follower switch M1 to the reference ground.

[0054]

[0055] Figure 3 The switch tube sequence module includes multiple parallel switch tubes. The drains of the switch tubes are connected to the gate of the power switch tube M0, and the sources are grounded. For example, n switch tubes M2[1:n]. For example, K2[1:n] in the appendix represents the control signals of the n switch tubes M2[1:n]. By selecting the number of switch tubes put into use, the equivalent resistance of the switch tube sequence module can be changed.

[0056] ​​Specifically, in this embodiment, the switch tube sequence module includes multiple parallel-connected NMOS tubes, which not only have switching characteristics but also have equivalent resistance when conducting. It can be understood that the NMOS tubes can also be replaced by other switch tubes.

[0057] The drive control circuit is connected to the gate voltage detection circuit, the current sequence module, the control end of the pre-stage switch S0, and the gates of the switch tubes respectively.

[0058] When it is necessary to turn on the power switch tube M0, the drive control circuit controls all the switch tubes of the switch tube sequence module to turn off, controls the pre-stage switch S0 to turn off so that the charging module uses the current output by the current sequence module for charging, and controls the current sequence module to generate a variable charging current, so that the gate voltage of the power switch tube M0 rises rapidly to close to the turn-on threshold of the power switch tube M0 and then rises slowly and remains at the turn-on threshold.

[0059] When it is necessary to turn off the power switch tube M0, the drive control circuit controls the current output by the current sequence module to be zero, simultaneously controls the pre-stage switch S0 to turn on to release the charge of the charging module so that the source follower switch M1 turns off, controls the switch tube sequence module to turn on and generate a variable equivalent resistance, so that the gate voltage of the power switch tube M0 drops rapidly to close to the turn-on threshold of the power switch tube M0 and then drops slowly to the turn-on threshold and then drops rapidly to zero.

[0060] Next, in conjunction with the attached Figure 4 , the conduction and turn-off processes of the power switch tube M0 in the present invention will be elaborated in detail.

[0061] 1) The conduction process of M0 is as follows:

[0062] The first stage (time period t0): The drive control circuit controls all the switch tubes M2[1:n] of the switch tube sequence module and the pre-stage switch S0 to turn off, controls the current sequence module to generate a charging current Is(N). In this stage, the magnitude of the charging current Is(N) is the first current Is0. The generated charging current Is(N) charges the charging capacitor C0, that is, the gate voltage Vc of the source follower switch M1 starts to rise rapidly, and at the same time, the gate voltage Vgate of the power switch tube M0 follows the gate voltage Vc of the source follower switch M1. Until the gate voltage detection circuit detects that the gate voltage Vgate of the power switch tube M0 rises to close to the turn-on threshold Vt0 and enters the second stage. Here, "close to" means that Vgate is smaller than Vt0 by a preset voltage difference. The preset voltage difference is a very small voltage, such as a voltage within 10% of Vt0.

[0063] Second stage (time period t1): Control the magnitude of the charging current Is(N) generated by the current sequence module to be the second current Is1 and start timing. The second current Is1 is less than the first current Is0. When the timing time reaches the first preset duration t1, enter the third stage. t1 is set internally by the drive control circuit.

[0064] During the t1 time period, since Is1 is small, the gate voltage Vc of the source follower switch M1 changes slowly. Moreover, there is a Miller effect in the power switch M0 (when the Vds voltage approaches the Vgs voltage, the parasitic capacitance Cgd between the gate and the drain will change with the voltage difference Vgd between the gate and the drain. When the Vds voltage is very close to the Vgs voltage, Cgd changes to the maximum). The gate voltage Vgate of the power switch M0 rises slowly and remains near the turn-on threshold Vt0. The power switch M0 starts to conduct when its gate voltage Vgate reaches Vt0. The current of the peripheral transformer or inductor starts to increase. The current from the drain to the source of the power switch M0 flows through the sampling resistor Rs to obtain the sampling voltage Vs. At this time, the Vs voltage is low, and the power switch M0 has low losses.

[0065] Third stage (time period t2): Control the magnitude of the charging current Is(N) generated by the current sequence module to be the third current Is2 and start timing. The third current Is2 is greater than the second current Is1. In this way, the gate voltage Vc of the source follower switch M1 quickly rises to the clamping voltage Vclamp of the clamping diode. At the same time, the gate voltage Vgate of the power switch M0 rises to Vclamp - Vgs. Vgs represents the voltage difference between the gate and the source when the source follower switch M1 is conducting. When the timing time reaches the second preset duration t2, enter the fourth stage;

[0066] Fourth stage (time period t3): Control the magnitude of the charging current Is(N) generated by the current sequence module to be the fourth current Is3. The fourth current Is3 is less than the third current Is2. In this way, the gate voltage Vc of the source follower switch M1 remains at the clamping voltage Vclamp. Thus, in this stage, mainly a small current is used to keep the gate voltage Vgate of the power switch M0 unchanged, reducing the drive power consumption.

[0067] 2) The turn-off process of M0 is as follows:

[0068] The first stage (time period t4): The drive control circuit controls the charging current Is(N) generated by the current sequence module to be 0. Meanwhile, the switch tube sequence module and the pre-stage switch S0 are turned on, and the equivalent resistance R2(on)_M2_N of the switch tube sequence module is the first equivalent resistance R2(on)_1. In this way, the gate voltage Vc of the source follower switch M1 rapidly drops to 0V, and the gate voltage Vgate of the power switch tube M0 rapidly drops until the gate voltage detection circuit detects that the gate voltage Vgate of the power switch tube M0 drops to near the turn-on threshold Vt0 and then enters the second stage. Here, "near" means that Vgate is larger than Vt0 by a preset voltage difference, and the preset voltage difference is a very small voltage, such as a voltage within 10% of Vt0.

[0069] The second stage (time period t5): Control the equivalent resistance R2(on)_M2_N of the switch tube sequence module to be the second equivalent resistance R(on)_2 and start timing. When the timing time reaches the third preset duration t5, enter the third stage. In this stage, since the second equivalent resistance R(on)_2 is greater than the first equivalent resistance R(on)_1, the gate voltage Vgate of the power switch tube M0 drops slowly. Due to the Miller effect of the power switch tube M0, Vgate remains near the turn-on threshold Vt0. At this time, the drain voltage of the power switch tube M0 is relatively low, and the power switch tube M0 has relatively low losses.

[0070] The third stage (time period t6): Control the equivalent resistance R2(on)_M2_N of the switch tube sequence module to be the third equivalent resistance R(on)_3, and the third equivalent resistance R(on)_3 is less than the second equivalent resistance R(on)_2 to rapidly reduce the gate voltage of the power switch tube M0 to zero.

[0071] In summary, this embodiment can achieve good EMI characteristics, which are reflected in that the Vs waveform has less interference and the rising and falling speeds of the drain voltage of the power switch tube are relatively smooth. Moreover, the switching delay is reduced and the efficiency is optimized, so it has wide applicability.

[0072] Embodiment 2

[0073] The power switch tube driving method of this embodiment is applied to the power switch tube driving circuit described above. The method includes:

[0074] S1) When it is necessary to turn on the power switch tube M0, the drive control circuit controls all the switch tubes of the switch tube sequence module to be turned off, controls the pre-stage switch S0 to be turned off, and controls the current sequence module to generate a variable charging current, so that the gate voltage of the power switch tube M0 rapidly rises to near the turn-on threshold of the power switch tube M0 and then slowly rises and remains at the turn-on threshold;

[0075] Among them, controlling the current sequence module to generate a variable charging current includes:

[0076] The first stage: controlling the current sequence module to generate a first current to rapidly increase the gate voltage of the power switch M0 until it is detected that the gate voltage of the power switch M0 rises close to the turn-on threshold, and then entering the second stage;

[0077] The second stage: controlling the current sequence module to generate a second current and start timing. The second current is less than the first current to cause the gate voltage of the power switch M0 to rise slowly in this stage and remain at the turn-on threshold. When the timing time reaches the first preset duration t1, enter the third stage;

[0078] The third stage: controlling the current sequence module to generate a third current and start timing. The third current is greater than the second current to cause the gate voltage of the source follower switch M1 to rapidly rise to the limit voltage Vclamp of the charging module. At the same time, the gate voltage of the power switch M0 rises to Vclamp - Vgs, where Vgs represents the voltage difference between the gate and the source when the source follower switch M1 is turned on. When the timing time reaches the second preset duration t2, enter the fourth stage;

[0079] The fourth stage: controlling the current sequence module to generate a fourth current. The fourth current is less than the third current to keep the gate voltage of the source follower switch M1 at the limit voltage Vclamp.

[0080] S2) When it is necessary to turn off the power switch M0, the drive control circuit controls the current output by the current sequence module to be zero, and at the same time controls the pre-stage switch S0 to conduct to release the charge of the charging module, thereby turning off the source follower switch M1. Controls the switch tube sequence module to conduct and generate a variable equivalent resistance, so that the gate voltage of the power switch M0 rapidly drops to close to the turn-on threshold of the power switch M0, then slowly drops to the turn-on threshold, and then rapidly drops to zero.

[0081] Among them, controlling the switch tube sequence module to conduct and generate a variable equivalent resistance includes:

[0082] The first stage: controlling the equivalent resistance of the switch tube sequence module to be a first equivalent resistance to rapidly decrease the gate voltage of the power switch M0 until it is detected that the gate voltage of the power switch M0 drops to close to the turn-on threshold, and then entering the second stage;

[0083] Second stage: Control the equivalent resistance of the switching transistor sequence module to be the second equivalent resistance and start timing. The second equivalent resistance is greater than the first equivalent resistance so that the gate voltage of the power switching transistor M0 slowly decreases and remains at the turn-on threshold in this stage. When the timing time reaches the third preset duration t5, enter the third stage;

[0084] Third stage: Control the equivalent resistance of the switching transistor sequence module to be the third equivalent resistance. The third equivalent resistance is less than the second equivalent resistance so that the gate voltage of the power switching transistor M0 quickly drops to zero.

[0085] For more content, reference can be made to Part One of the embodiments, which will not be elaborated here.

[0086] Terms such as "equal", "same", "simultaneous", "maintain" or other similar terms in this document do not limit to absolute equality or sameness in mathematical terms. When implementing the rights of this patent, it can be approximate in engineering sense or within an acceptable error range. The "connected" or "coupled" not only includes directly connecting two entities, but also includes indirectly connecting through other entities with beneficial improvement effects.

[0087] The ordinal terms such as "first", "second", etc. used in this specification can be used to describe various components, but these components are not limited by these terms. The purpose of using these terms is only to distinguish one component from other components. For example, without departing from the scope of the rights of the present invention, the first component can be named the second component, and similarly, the second component can also be named the first component.

[0088] The embodiments of the present invention have been described above in conjunction with the accompanying drawings. However, the present invention is not limited to the above specific embodiments. The above specific embodiments are merely illustrative and not restrictive. Under the inspiration of the present invention, those of ordinary skill in the art can also make many forms without departing from the spirit and scope protected by the claims of the present invention. All of these are within the protection scope of the present invention.

Claims

1. A power switch tube drive circuit, characterized in that The driving circuit includes: a gate voltage detection circuit connected to the gate of the power switch tube for detecting the gate voltage of the power switch tube in real time; a source follower switch, the drain of the source follower switch is connected to the power supply, and the source is connected to the gate of the power switch tube; a charging module and a current sequence module, the current sequence module is connected to the charging module, and the charging module is connected between the gate of the source follower switch and the ground for charging with the current output by the current sequence module to generate a voltage and supply it to the gate of the source follower switch; a switch tube sequence module including a plurality of parallel-connected switch tubes, the drain of the switch tube is connected to the gate of the power switch tube, and the source of the switch tube is grounded; a driving control circuit connected to the gate voltage detection circuit, the current sequence module, the gate of the source follower switch, and the gate of the switch tube respectively. When it is necessary to turn on the power switch tube, the driving control circuit controls all the switch tubes of the switch tube sequence module to turn off, controls the current sequence module to generate a variable charging current, so that the gate voltage of the power switch tube rises rapidly until it is close to the turn-on threshold of the power switch tube and then rises slowly and remains at the turn-on threshold; when it is necessary to turn off the power switch tube, the driving control circuit controls the current output by the current sequence module to be zero so that the source follower switch turns off, controls the switch tube sequence module to turn on and generate a variable equivalent resistance, so that the gate voltage of the power switch tube drops rapidly until it is close to the turn-on threshold of the power switch tube and then drops slowly to the turn-on threshold and then drops rapidly to zero.

2. The power switch tube drive circuit according to claim 1, characterized in that The controlling the current sequence module to generate a variable charging current includes: The first stage: controlling the current sequence module to generate a first current to rapidly increase the gate voltage of the power switch tube until it is detected that the gate voltage of the power switch tube rises to close to the turn-on threshold and then enters the second stage; The second stage: controlling the current sequence module to generate a second current and start timing. The second current is less than the first current so that the gate voltage of the power switch tube rises slowly in this stage and remains at the turn-on threshold. When the timing time reaches the first preset duration, it enters the third stage; The third stage: controlling the current sequence module to generate a third current and start timing. The third current is greater than the second current so that the gate voltage of the source follower switch rises rapidly to the limit voltage Vclamp of the charging module, and at the same time the gate voltage of the power switch tube follows and rises to Vclamp - Vgs, where Vgs represents the voltage difference between the gate and the source when the source follower switch is turned on. When the timing time reaches the second preset duration, it enters the fourth stage; The fourth stage: controlling the current sequence module to generate a fourth current, and the fourth current is less than the third current so that the gate voltage of the source follower switch remains at the limit voltage Vclamp.

3. The power switch tube driving circuit according to claim 1, wherein The controlling the switch tube sequence module to turn on and generate a variable equivalent resistance includes: First stage: Control the equivalent resistance of the switch tube sequence module to be a first equivalent resistance so that the gate voltage of the power switch tube drops rapidly until it is detected that the gate voltage of the power switch tube drops to near the turn-on threshold, and then enter the second stage; Second stage: Control the equivalent resistance of the switch tube sequence module to be a second equivalent resistance and start timing. The second equivalent resistance is greater than the first equivalent resistance so that the gate voltage of the power switch tube drops slowly in this stage and remains at the turn-on threshold. When the timing time reaches a third preset duration, enter the third stage; Third stage: Control the equivalent resistance of the switch tube sequence module to be a third equivalent resistance. The third equivalent resistance is less than the second equivalent resistance so that the gate voltage of the power switch tube drops rapidly to zero.

4. The power switch tube drive circuit according to claim 1, characterized in that, The charging module includes a clamping zener diode and a charging capacitor. The charging capacitor is connected between the gate of the source follower switch and the ground. The negative electrode of the clamping zener diode is connected to the gate of the source follower switch, and the positive electrode is grounded.

5. The power switch tube driving circuit according to claim 4, characterized in that, The drive circuit further includes a pre-stage switch. The pre-stage switch is connected between the gate of the source follower switch and the ground. The control end of the pre-stage switch is connected to the drive control circuit; When it is necessary to turn on the power switch tube, the drive control circuit controls the pre-stage switch to turn off so that the charging module charges using the current output by the current sequence module; When it is necessary to turn off the power switch tube, the drive control circuit controls the pre-stage switch to turn on to release the charge of the charging module, thereby turning off the source follower switch.

6. The power switch tube driving circuit according to claim 1, wherein The current sequence module includes a plurality of parallel current sources, and the switch tube sequence module includes a plurality of parallel MOS tubes.

7. A power switch tube driving method, applied to the power switch tube driving circuit according to any one of claims 1-6, characterized in that, The method includes: When it is necessary to turn on the power switch tube, the drive control circuit controls all the switch tubes of the switch tube sequence module to turn off, and controls the current sequence module to generate a variable charging current so that the gate voltage of the power switch tube rises rapidly to near the turn-on threshold of the power switch tube and then rises slowly and remains at the turn-on threshold; When it is necessary to turn off the power switch tube, the drive control circuit controls the current output by the current sequence module to be zero so that the source follower switch turns off, and controls the switch tube sequence module to turn on and generate a variable equivalent resistance so that the gate voltage of the power switch tube drops rapidly to near the turn-on threshold of the power switch tube and then drops slowly to the turn-on threshold and then drops rapidly to zero.

8. The power switch tube driving method according to claim 7, wherein The controlling the current sequence module to generate a variable charging current includes: First stage: Control the current sequence module to generate a first current so that the gate voltage of the power switch tube rises rapidly until it is detected that the gate voltage of the power switch tube rises to near the turn-on threshold, and then enter the second stage; Second stage: Control the current sequence module to generate a second current and start timing. The second current is less than the first current so that the gate voltage of the power switch tube rises slowly in this stage and remains at the turn-on threshold. When the timing time reaches a first preset duration, enter the third stage; Third stage: Control the current sequence module to generate a third current and start timing. The third current is greater than the second current so that the gate voltage of the source follower switch rapidly rises to the limit voltage Vclamp of the charging module. At the same time, the gate voltage of the power switch transistor rises to Vclamp - Vgs, where Vgs represents the voltage difference between the gate and the source when the source follower switch is turned on. When the timing time reaches the second preset duration, enter the fourth stage; Fourth stage: Control the current sequence module to generate a fourth current. The fourth current is less than the third current so that the gate voltage of the source follower switch is maintained at the limit voltage Vclamp.

9. The power switch tube driving method according to claim 7, wherein The controlling the switch transistor sequence module to turn on and generate a variable equivalent resistance includes: First stage: Control the equivalent resistance of the switch transistor sequence module to be a first equivalent resistance so that the gate voltage of the power switch transistor rapidly drops until it is detected that the gate voltage of the power switch transistor drops to near the turn-on threshold, and then enter the second stage; Second stage: Control the equivalent resistance of the switch transistor sequence module to be a second equivalent resistance and start timing. The second equivalent resistance is greater than the first equivalent resistance so that the gate voltage of the power switch transistor slowly drops and remains at the turn-on threshold during this stage. When the timing time reaches the third preset duration, enter the third stage; Third stage: Control the equivalent resistance of the switch transistor sequence module to be a third equivalent resistance. The third equivalent resistance is less than the second equivalent resistance so that the gate voltage of the power switch transistor rapidly drops to zero.

10. The power switch tube driving method according to claim 7, wherein The charging module includes a clamping zener diode and a charging capacitor. The charging capacitor is connected between the gate of the source follower switch and the ground. The negative pole of the clamping zener diode is connected to the gate of the source follower switch, and the positive pole is grounded. The drive circuit further includes a pre-stage switch, which is connected between the gate of the source follower switch and the ground. The control terminal of the pre-stage switch is connected to the drive control circuit; The method further includes: when it is necessary to turn on the power switch transistor, the drive control circuit controls the pre-stage switch to turn off so that the charging module charges using the current output by the current sequence module; when it is necessary to turn off the power switch transistor, the drive control circuit controls the pre-stage switch to turn on to release the charge of the charging module, thereby turning off the source follower switch.

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