A darlington tube driving circuit, method and switching power management chip

Abstract

The application discloses a Darlington tube driving circuit, a method and a switching power management chip. The driving circuit is used for driving the Darlington tube to alternately work in a conduction period and an off period. The driving circuit comprises a first driving source, a second driving source and a control module. The first driving source is connected with the control end of a front-stage tube and is used for providing driving current for the front-stage tube. The second driving source is connected with the control end of a rear-stage tube and is used for providing driving current for the rear-stage tube. The control module is used for synchronously controlling the second driving source to start driving the rear-stage tube at the beginning of each conduction period, controlling the first driving source to start driving the front-stage tube after the rear-stage tube is completely turned on, synchronously controlling the second driving source to stop driving the rear-stage tube while the first driving source starts driving the front-stage tube, and controlling the first driving source to stop driving the front-stage tube when it is needed to end the current conduction period. The application can reduce the power loss when the Darlington tube is turned on.

Description

Technical Field

[0001] This invention relates to the field of electronic circuit technology, and in particular to a Darlington transistor driving circuit, method, and switching power supply management chip. Background Technology

[0002] Figure 1 This is a schematic diagram of an existing Darlington flyback power supply, mainly consisting of three control MOSFETs M1, M2, and M3, and two drive ports Q1B and Q2B. M1 is used as a switch. When the control module issues a turn-on command, switch M1 turns on, and M2 and M3 turn off. At this time, the Ibase current flows through port Q1B to the Darlington MOSFET, turning it on and causing the voltage at the CS node to rise. When the voltage at the CS node rises to REF1, M1 turns off, and Ibase cannot flow into the Darlington NPN transistor. When the voltage at the CS node rises to REF2, the control module issues a turn-off command, turning on M2 and M3 and pulling Q1B and Q2B low to GND. One limitation of existing driving methods is that the base current Ibase of the transistor Q2 following the Darlington transistor originates from the collector (C) of the first preceding transistor. Therefore, after the Darlington transistor is turned on, the VCE voltage must be greater than the base-emitter voltage VBE2 of the following transistor Q2 (typically 0.65V). Figure 2 As shown, the voltage of VCE is greater than 0.65V, therefore there is a large conduction power loss. Summary of the Invention

[0003] The technical problem to be solved by this invention is to address the significant power loss defect of Darlington transistors during conduction in existing technologies, and to provide a Darlington transistor driving circuit, method, and switching power supply management chip, aiming to reduce the power loss during conduction.

[0004] The technical solution adopted by this invention to solve its technical problem is:

[0005] On one hand, a Darlington transistor driving circuit is constructed, wherein the Darlington transistor includes a pre-stage transistor and a post-stage transistor, and the driving circuit is used to drive the Darlington transistor to alternately operate in the on-cycle and off-cycle, the driving circuit comprising:

[0006] The first driving source is connected to the control terminal of the preamplifier and is used to provide driving current to the preamplifier.

[0007] The second driving source is connected to the control terminal of the subsequent transistor and is used to provide driving current to the subsequent transistor.

[0008] The control module is connected to the first driving source and the second driving source respectively, and is used to synchronously control the second driving source to start driving the post-stage transistor at the beginning of each conduction cycle, control the first driving source to start driving the pre-stage transistor after the post-stage transistor is fully turned on, and simultaneously control the second driving source to stop driving the post-stage transistor while controlling the first driving source to start driving the pre-stage transistor, and control the first driving source to stop driving the pre-stage transistor when it is necessary to end the current conduction cycle.

[0009] Preferably, the driving circuit further includes a sampling and detection circuit, which is connected to the output of the subsequent transistor and the control module respectively, for detecting the sampling voltage generated by the current output from the subsequent transistor and feeding it back to the control module;

[0010] The control module is specifically used in each conduction cycle to: first control the second driving source to start driving the subsequent transistor; when the sampling voltage rises to the first reference voltage, control the first driving source to start driving the preceding transistor and simultaneously control the second driving source to stop driving the subsequent transistor; when the sampling voltage continues to rise to the second reference voltage, determine that the current conduction cycle needs to be ended, and control the first driving source to stop driving the preceding transistor.

[0011] Preferably, the driving circuit further includes:

[0012] The first discharge circuit is connected to the control terminal of the preamplifier and is used to discharge the control terminal of the preamplifier so that the preamplifier is completely turned off.

[0013] The second discharge circuit is connected to the control terminal of the subsequent transistor and is used to discharge the control terminal of the subsequent transistor so that the subsequent transistor is completely turned off.

[0014] The control module is specifically used in each conduction cycle to: control the second driving source to start driving the subsequent transistor, and simultaneously control the first discharge circuit and the second discharge circuit to stop discharging; when the sampling voltage rises to the third reference voltage, control the first discharge circuit and the second discharge circuit to start discharging, wherein the third reference voltage is greater than the second reference voltage.

[0015] Preferably, the first reference voltage is 20% to 50% of the third reference voltage.

[0016] Preferably, the first discharge circuit includes a first discharge switch, the second discharge circuit includes a second discharge switch, the first discharge switch is connected between the control terminal of the preamplifier and ground, the second discharge switch is connected between the control terminal of the amplifier and ground, and the control terminals of the first discharge switch and the second discharge switch are connected to the control module.

[0017] Preferably, the first driving source includes a first power supply and a first driving switch, the second driving source includes a second power supply and a second driving switch, the first driving switch is connected between the first power supply and the control terminal of the preamplifier, the second driving switch is connected between the first power supply and the control terminal of the power amplifier, and the control terminals of the first driving switch and the second driving switch are respectively connected to the control module.

[0018] Preferably, both the first drive switch and the second drive switch are MOSFETs.

[0019] Secondly, a switching power supply management chip is constructed for connecting an external Darlington transistor, and the chip internally includes the Darlington transistor driving circuit as described above.

[0020] Three aspects are addressed: a Darlington transistor driving method is constructed, wherein the Darlington transistor includes a pre-stage transistor and a post-stage transistor, and the driving method includes:

[0021] At the beginning of each conduction cycle, the second drive source is synchronously controlled to start driving the subsequent transistor;

[0022] After the power stage transistor is fully turned on, the first drive source is controlled to start driving the power stage transistor, and at the same time as the first drive source is controlled to start driving the power stage transistor, the second drive source is simultaneously controlled to stop driving the power stage transistor.

[0023] When it is necessary to end the current conduction cycle, control the first drive source to stop driving the preamplifier.

[0024] Preferably, the method specifically includes:

[0025] In each conduction cycle, the first discharge circuit and the second discharge circuit are first controlled to stop discharging, and the second drive source is simultaneously controlled to start driving the subsequent transistor.

[0026] When the sampling voltage rises to the first reference voltage, the first driving source is controlled to start driving the pre-stage transistor and the second driving source is simultaneously controlled to stop driving the post-stage transistor.

[0027] When the sampling voltage continues to rise to the second reference voltage, it is determined that the current conduction cycle needs to be ended, and the first driving source is controlled to stop driving the pre-amplifier.

[0028] When the sampling voltage continues to rise to the third reference voltage, the first discharge circuit and the second discharge circuit are controlled to start discharging.

[0029] The first reference voltage is 20% to 50% of the third reference voltage.

[0030] The Darlington transistor driving circuit, method, and switching power supply management chip of the present invention have the following beneficial effects: The Darlington transistor in the present invention is driven in segments. At the beginning of the conduction cycle, the driving of the preceding stage transistor is not started temporarily. Instead, the driving source is used directly to drive the following stage transistor. Only after the following stage transistor is fully turned on will the driving source of the following stage transistor be turned off and the driving source of the preceding stage transistor be started to drive the entire Darlington transistor. Because the following stage transistor has been fully turned on before, the driving current of the following stage transistor does not depend on the preceding stage transistor. The voltage at the input terminal of the following stage transistor can be less than the control terminal voltage. Therefore, when the following stage transistor is turned on, the voltage drop between the input terminal and the output terminal does not need to be greater than the base-emitter voltage when the transistor is turned on. This will reduce the power loss when the Darlington transistor is turned on. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort:

[0032] Figure 1 This is a schematic diagram of an existing Darlington flyback power supply;

[0033] Figure 2 yes Figure 1 The circuit waveform diagram shown is shown below.

[0034] Figure 3 This is a schematic diagram of the Darlington transistor drive circuit of the present invention;

[0035] Figure 4 This is a schematic diagram of the switching power supply management chip that integrates a Darlington transistor drive circuit according to the present invention.

[0036] Figure 5 yes Figure 4 The circuit waveform diagram shown is shown. Detailed Implementation

[0037] To address the significant power loss during Darlington transistor conduction, this invention presents a Darlington transistor driving circuit, method, and switching power supply management chip. The driving circuit includes two driving sources connected to the control terminals of the preceding and following transistors, respectively. This invention utilizes these two driving sources to drive the Darlington transistor in segments: at the beginning of the conduction cycle, the driving of the preceding transistor is not initiated; instead, the following transistor is driven directly using the driving source. Only after the following transistor is fully turned on is the driving source for the following transistor turned off, and the driving source for the preceding transistor is activated to drive the entire Darlington transistor. Thus, because the following transistor is already fully turned on, its driving current is independent of the preceding transistor. The voltage at the input terminal of the following transistor can be lower than the control terminal voltage. Therefore, the voltage drop between the input and output terminals of the following transistor does not need to exceed the base-emitter voltage when the transistor is on, which reduces the power loss during Darlington transistor conduction.

[0038] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Typical embodiments of the invention are shown in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to make the disclosure of the present invention more thorough and complete. It should be understood that the embodiments of the present invention and the specific features thereof are detailed descriptions of the technical solutions of this application, and not limitations thereof. Where there is no conflict, the embodiments of the present invention and the technical features thereof can be combined with each other.

[0039] refer to Figure 3 The Darlington transistor 100 includes a pre-stage transistor Q1 and a post-stage transistor Q2. The driving circuit of the present invention is used to drive the Darlington transistor 100 to operate alternately during the on-cycle and the off-cycle. The driving circuit includes:

[0040] The first driving source 21 is connected to the control terminal of the preamplifier Q1 and is used to provide driving current to the preamplifier Q1.

[0041] The second driving source 22 is connected to the control terminal of the subsequent transistor Q2 and is used to provide driving current to the subsequent transistor Q2.

[0042] The control module 1 is connected to the first drive source 21 and the second drive source 22 respectively. It is used to synchronously control the second drive source 22 to start driving the downstream transistor Q2 at the beginning of each conduction cycle, control the first drive source 21 to start driving the upstream transistor Q1 after the downstream transistor Q2 is fully turned on, and simultaneously control the second drive source 22 to stop driving the downstream transistor Q2 while controlling the first drive source 21 to start driving the upstream transistor Q1, and control the first drive source 21 to stop driving the upstream transistor Q1 when it is necessary to end the current conduction cycle.

[0043] Theoretically, control module 1 can control the timing of the first driving source 21 and the second driving source 22 through timing, because this driving circuit is ultimately applied to a specific scenario, such as a switching power supply. In a switching power supply, the output of the Darlington transistor Q2 is grounded through a sampling resistor Rcs, and the switching power supply controls the Darlington's duty cycle based on the sampling voltage of the sampling resistor Rcs. Therefore, considering the switching control characteristics of the switching transistor in the switching power supply, in the driving circuit of this invention, control module 1 uses the magnitude of the feedback sampling voltage to control the timing of the first driving source 21 and the second driving source 22.

[0044] Therefore, preferably, the driving circuit of the present invention further includes a sampling and detection circuit 4, which is connected to the output of the subsequent transistor Q2 and the control module 1 respectively, for detecting the sampling voltage generated by the current output from the subsequent transistor Q2 and feeding it back to the control module 1. Accordingly, the control module 1 is specifically used in each conduction cycle to: first control the second driving source 22 to start driving the subsequent transistor Q2; when the sampling voltage rises to the first reference voltage Ref0, control the first driving source 21 to start driving the preceding transistor Q1 and simultaneously control the second driving source 22 to stop driving the subsequent transistor Q2; when the sampling voltage continues to rise to the second reference voltage Ref1, it is determined that the current conduction cycle needs to be ended, and the first driving source 21 is controlled to stop driving the preceding transistor Q1, wherein the second reference voltage Ref1 is greater than the first reference voltage Ref0.

[0045] Because when the drive to Darlington transistor 100 is removed, Darlington transistor 100 does not immediately turn off, but continues to conduct for a period of time. During this time, the current flowing through Darlington transistor 100 will continue to rise. In order to limit the current flowing through Darlington transistor 100, the drive circuit of the present invention further includes:

[0046] The first discharge circuit 31 is connected to the control terminal of the preamplifier Q1 and is used to discharge the control terminal of the preamplifier Q1 so that the preamplifier Q1 is completely turned off.

[0047] The second discharge circuit 32 is connected to the control terminal of the subsequent transistor Q2 and is used to discharge the control terminal of the subsequent transistor Q2 so that the subsequent transistor Q2 is completely turned off.

[0048] Accordingly, the control module 1 is specifically used in each conduction cycle to: control the second driving source 22 to start driving the subsequent transistor Q2, and simultaneously control the first discharge circuit 31 and the second discharge circuit 32 to stop discharging; when the sampling voltage rises to the third reference voltage Ref2, control the first discharge circuit 31 and the second discharge circuit 32 to start discharging until the next conduction cycle. That is, during the Darlington transistor 100 turn-off cycle, the first discharge circuit 31 and the second discharge circuit 32 are both in a discharging state. The third reference voltage Ref2 is greater than the second reference voltage Ref1.

[0049] In addition, the sampling and detection circuit 4 of the present invention can be implemented using PWM comparators. For example, since the sampling voltage in the present invention will be compared with three reference voltages (first reference voltage Ref0, second reference voltage Ref1, and third reference voltage Ref2), three PWM comparators can be designed. The first input of these three PWM comparators is connected to the output of the subsequent transistor Q2. The second input of these three PWM comparators is connected to the first reference voltage Ref0, the second reference voltage Ref1, and the third reference voltage Ref2, respectively. The output of these three PWM comparators is connected to the control module 1. The control module 1 can determine whether the sampling voltage has risen to the corresponding reference voltage based on whether the output signals of these three PWM comparators have flipped.

[0050] Preferably, the first reference voltage Ref0 is 20% to 50% of the third reference voltage Ref2, and the specific value can be determined according to the NPN characteristics of the actual Darlington transistor 100.

[0051] The following section provides a detailed explanation using the example of a driver circuit applied to a switching power supply management chip 200.

[0052] The switching power supply management chip 200 provides a ground pin (GND), a sampling pin (CS), and two drive pins (Q1B and Q2B). An external Darlington transistor 100 and a sampling resistor (Rcs) are connected to the chip 200. The sampling resistor Rcs is connected between the sampling pin (CS) and the ground pin (GND). The control terminal of the preceding transistor Q1 of the Darlington transistor 100 is connected to the drive pin Q1B, and the control terminal of the following transistor Q2 is connected to the drive pin Q2B. The input of the Darlington transistor 100, which is also the input of the following transistor Q2, is connected to an external input power supply Vin via the primary winding of a transformer. This external input power supply Vin can be DC or AC. The output of the Darlington transistor 100, which is also the output of the following transistor Q2, is connected to the sampling pin (CS).

[0053] Specifically, the first discharge circuit 31 includes a first discharge switch, the second discharge circuit 32 includes a second discharge switch, the first driving source 21 includes a first power supply (outputting Ibase1 current) and a first driving switch, and the second driving source 22 includes a second power supply (outputting Ibase2 current) and a second driving switch. In this embodiment, both the first discharge switch and the second discharge switch are MOSFETs, specifically NMOS transistors. Both the first driving switch and the second driving switch are MOSFETs, specifically PMOS transistors.

[0054] The first discharge switch is connected between the drive pin Q1B (i.e., the control terminal of the preamplifier Q1) and ground, and the second discharge switch is connected between the drive pin Q2B (i.e., the control terminal of the amplifier Q2) and ground. The control terminals of the first and second discharge switches are connected to the control module 1. The first drive switch is connected between the first power supply and the drive pin Q1B (i.e., the control terminal of the preamplifier Q1), and the second drive switch is connected between the first power supply and the drive pin Q2B (i.e., the control terminal of the amplifier Q2). The control terminals of the first and second drive switches are respectively connected to the control module 1.

[0055] Combination Figure 4 , 5 The working principle of this invention is as follows:

[0056] like Figure 5 When the control module 1 issues a turn-on command, the control module 1 flips the MP2G, MN1G, and MN2G signals. The MP1G signal remains unchanged, so only the switch MP2 of the second drive source 22 starts to turn on, and the switches MN1 and MN2 of the two discharge circuits 31 and 32 start to turn off. The switch MP1 of the first drive source 21 remains off. At this time, the Ibase2 current of the second drive source 22 flows through the Q2B port to the stage Q2 of the Darlington tube 100. The stage Q2 turns on, and the sampling voltage Vcs rises.

[0057] When the sampling voltage Vcs rises to the first reference voltage REF0, the MP2G and MP1G signals flip, so the switch MP1 of the first driving source 21 is turned on and the switch MP2 of the second driving source 22 is turned off. The Ibase2 current of the second driving source 22 begins to turn off, and the Ibase1 current of the first driving source 21 is turned on and flows through the Q1B port to the preamplifier Q1 of the Darlington transistor 100. After being amplified by the preamplifier Q1, it flows into the collector C of the subsequent transistor Q2.

[0058] When the sampling voltage Vcs rises to the second reference voltage REF1, the MP1G signal flips, so the switch MP1 of the first drive source 21 is turned off, and the Ibase current cannot flow into the Darlington tube 100.

[0059] When the sampling voltage Vcs rises to the third reference voltage Ref2, the MN1G and MN2G signals flip, and the switches MN1 and MN2 of the two discharge circuits 31 and 32 begin to conduct, pulling Q1B and Q2B low to GND.

[0060] Since the base current of the subsequent transistor Q2 does not depend on the preceding transistor Q1 when it is turned on, VC can be less than the base voltage of the subsequent transistor Q2. That is, the voltage VCE does not need to be greater than the base-emitter voltage VBE2 of the subsequent transistor Q2, which will reduce the power loss when the Darlington transistor NPN is turned on.

[0061] Based on the same inventive concept, this invention also claims a Darlington transistor driving method, the driving method comprising: synchronously controlling a second driving source 22 to start driving the subsequent stage transistor Q2 at the beginning of each conduction cycle; controlling a first driving source 21 to start driving the preceding stage transistor Q1 after the subsequent stage transistor Q2 is fully turned on, and simultaneously controlling the second driving source 22 to stop driving the subsequent stage transistor Q2 while controlling the first driving source 21 to start driving the preceding stage transistor Q1; and controlling the first driving source 21 to stop driving the preceding stage transistor Q1 when it is necessary to end the current conduction cycle.

[0062] More specifically, the method includes:

[0063] In each conduction cycle, the first discharge circuit 31 and the second discharge circuit 32 are first controlled to stop discharging, and the second drive source 22 is simultaneously controlled to start driving the subsequent transistor Q2.

[0064] When the sampling voltage rises to the first reference voltage Ref0, the first driving source 21 is controlled to start driving the pre-stage transistor Q1 and the second driving source 22 is simultaneously controlled to stop driving the post-stage transistor Q2.

[0065] When the sampling voltage continues to rise to the second reference voltage Ref1, it is determined that the current conduction cycle needs to be ended, and the first driving source 21 is controlled to stop driving the front-end transistor Q1.

[0066] When the sampling voltage continues to rise to the third reference voltage Ref2, the first discharge circuit 31 and the second discharge circuit 32 are controlled to start discharging.

[0067] Wherein, the first reference voltage Ref0 is 20% to 50% of the third reference voltage Ref2.

[0068] For more details, please refer to the Circuit Implementation Examples section.

[0069] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, it can include the processes of the embodiments of the methods described above. For example, the execution entity of the above methods can be control module 1.

[0070] In summary, the Darlington transistor driving circuit, method, and switching power supply management chip of the present invention have the following beneficial effects: The Darlington transistor in the present invention is driven in segments. At the beginning of the conduction cycle, the driving of the preceding stage transistor is not started temporarily. Instead, the driving source is used directly to drive the following stage transistor. Only after the following stage transistor is fully turned on will the driving source of the following stage transistor be turned off and the driving source of the preceding stage transistor be started to drive the entire Darlington transistor. Because the following stage transistor has been fully turned on before, the driving current of the following stage transistor does not depend on the preceding stage transistor. The voltage at the input terminal of the following stage transistor can be less than the control terminal voltage. Therefore, when the following stage transistor is turned on, the voltage drop between the input terminal and the output terminal does not need to be greater than the base-emitter voltage when the transistor is turned on. This will reduce the power loss when the Darlington transistor is turned on.

[0071] The terms "equal to," "equivalent to," "synchronous," or other similar expressions are not limited to absolute equality or sameness in mathematical terms. When applying the rights described in this patent, they can refer to similarity in an engineering sense or within an acceptable error range. The term "connected" or "linked" includes not only directly connecting two entities but also indirectly connecting them through other entities that have beneficial improvement effects.

[0072] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0073] The terms "first," "second," and other ordinal numbers used in this specification are used to describe various constituent elements, but these constituent elements are not limited by these terms. The purpose of using these terms is solely to distinguish one constituent element from others. For example, without departing from the scope of the invention, a first constituent element may be named a second constituent element, and similarly, a second constituent element may be named a first constituent element.

[0074] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims. All of these forms are within the protection scope of the present invention.

Claims

1. A Darlington transistor driving circuit, wherein the Darlington transistor comprises a pre-stage transistor and a post-stage transistor, characterized in that, The driving circuit is used to drive the Darlington transistor to operate alternately during the on-cycle and off-cycle. The driving circuit includes: The first driving source is connected to the control terminal of the preamplifier and is used to provide driving current to the preamplifier. The second driving source is connected to the control terminal of the subsequent transistor and is used to provide driving current to the subsequent transistor. The control module is connected to the first driving source and the second driving source respectively, and is used to synchronously control the second driving source to start driving the post-stage transistor at the beginning of each conduction cycle, control the first driving source to start driving the pre-stage transistor after the post-stage transistor is fully turned on, and simultaneously control the second driving source to stop driving the post-stage transistor while controlling the first driving source to start driving the pre-stage transistor, and control the first driving source to stop driving the pre-stage transistor when it is necessary to end the current conduction cycle.

2. The Darlington transistor drive circuit according to claim 1, characterized in that, The driving circuit also includes a sampling and detection circuit, which is connected to the output of the subsequent transistor and the control module respectively, and is used to detect the sampling voltage generated by the current output from the subsequent transistor and feed it back to the control module. The control module is specifically used in each conduction cycle to: first control the second driving source to start driving the subsequent transistor; when the sampling voltage rises to the first reference voltage, control the first driving source to start driving the preceding transistor and simultaneously control the second driving source to stop driving the subsequent transistor; When the sampling voltage continues to rise to the second reference voltage, it is determined that the current conduction cycle needs to be ended, and the first driving source is controlled to stop driving the preamplifier.

3. The Darlington transistor drive circuit according to claim 2, characterized in that, The driving circuit also includes: The first discharge circuit is connected to the control terminal of the preamplifier and is used to discharge the control terminal of the preamplifier so that the preamplifier is completely turned off. The second discharge circuit is connected to the control terminal of the subsequent transistor and is used to discharge the control terminal of the subsequent transistor so that the subsequent transistor is completely turned off. The control module is specifically used in each conduction cycle to: control the second driving source to start driving the subsequent transistor, and simultaneously control the first discharge circuit and the second discharge circuit to stop discharging; when the sampling voltage rises to the third reference voltage, control the first discharge circuit and the second discharge circuit to start discharging, wherein the third reference voltage is greater than the second reference voltage.

4. The Darlington transistor drive circuit according to claim 3, characterized in that, The first reference voltage is 20% to 50% of the third reference voltage.

5. The Darlington transistor drive circuit according to claim 3, characterized in that, The first discharge circuit includes a first discharge switch, and the second discharge circuit includes a second discharge switch. The first discharge switch is connected between the control terminal of the preamplifier and ground, and the second discharge switch is connected between the control terminal of the amplifier and ground. The control terminals of the first discharge switch and the second discharge switch are connected to the control module.

6. The Darlington transistor drive circuit according to claim 1, characterized in that, The first driving source includes a first power supply and a first driving switch, and the second driving source includes a second power supply and a second driving switch. The first driving switch is connected between the first power supply and the control terminal of the preamplifier, and the second driving switch is connected between the first power supply and the control terminal of the power amplifier. The control terminals of the first driving switch and the second driving switch are respectively connected to the control module.

7. The Darlington transistor drive circuit according to claim 6, characterized in that, Both the first drive switch and the second drive switch are MOSFETs.

8. A switching power supply management chip for connecting an external Darlington transistor, characterized in that, The chip internally includes a Darlington transistor drive circuit as described in any one of claims 1-7.

9. A Darlington transistor driving method, wherein the Darlington transistor comprises a preamplifier and a postamplifier, characterized in that, The Darlington transistor driving method is applied to the Darlington transistor driving circuit as described in any one of claims 1-7, and the driving method includes: At the beginning of each conduction cycle, the second drive source is synchronously controlled to start driving the subsequent transistor; After the power stage transistor is fully turned on, the first drive source is controlled to start driving the power stage transistor, and at the same time as the first drive source is controlled to start driving the power stage transistor, the second drive source is simultaneously controlled to stop driving the power stage transistor. When it is necessary to end the current conduction cycle, control the first drive source to stop driving the preamplifier.

10. The Darlington transistor driving method according to claim 9, characterized in that, The method specifically includes: In each conduction cycle, the first discharge circuit and the second discharge circuit are first controlled to stop discharging, and the second drive source is simultaneously controlled to start driving the subsequent transistor. When the sampling voltage rises to the first reference voltage, the first driving source is controlled to start driving the pre-stage transistor and the second driving source is simultaneously controlled to stop driving the post-stage transistor. When the sampling voltage continues to rise to the second reference voltage, it is determined that the current conduction cycle needs to be ended, and the first driving source is controlled to stop driving the pre-amplifier. When the sampling voltage continues to rise to the third reference voltage, the first discharge circuit and the second discharge circuit are controlled to start discharging. Wherein, the first reference voltage is 20% to 50% of the third reference voltage; The output terminal of the power transistor is grounded via a sampling resistor, and the sampling voltage is the voltage generated across the sampling resistor by the output current of the power transistor.

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