CN118677220B

CN118677220B - A control method for a power switch tube, a control circuit and a switching power supply

Info

Publication number: CN118677220B
Application number: CN202411170612.5A
Authority: CN
Inventors: 李恒义; 王浩丞; 郭伟峰
Original assignee: Shenzhen Sunmoon Microelectronics Co Ltd
Current assignee: Shenzhen Sunmoon Microelectronics Co Ltd
Priority date: 2024-08-26
Filing date: 2024-08-26
Publication date: 2025-02-28
Anticipated expiration: 2044-08-26
Also published as: CN118677220A

Abstract

The present application is applicable to the field of integrated circuit technology, and provides a control method for a power switch tube, a control circuit and a switching power supply. The control method includes: when receiving a start signal of the power switch tube, generating a start control signal for controlling the start of a first power switch tube and a second power switch tube according to a current feedback signal; sending the start control signal to a drive delay control circuit and a first drive circuit respectively, so that the first drive circuit outputs a first drive current signal to control the start of the first power switch tube; after the first power switch tube is turned on for a preset time period, the drive delay control circuit sends the start control signal to the second drive circuit, so that it outputs a second drive current signal to control the start of the second power switch tube; wherein the first power switch tube is an external chip sealed power tube, and the second power switch tube is a chip built-in power tube, thereby solving the problem of increased design cost and manufacturing cost caused by using large-sized power switch tubes.

Description

Control method and control circuit of power switch tube and switch power supply

Technical Field

The application belongs to the technical field of integrated circuits, and particularly relates to a control method, a control circuit and a switching power supply of a power switch tube.

Background

Power switching tubes are a core element in switching power supplies. The switching power supply realizes the conversion of electric energy by controlling the on-off of the power switching tube, converts the input voltage into a high-frequency alternating current signal through a high-frequency switching technology, and outputs stable direct current through a rectifying and filtering circuit. The performance of the power switch tube directly affects key indexes such as efficiency, stability, volume, weight and the like of the switch power supply.

As the power demand of the switching power supply increases, the current demand of the power switching tube is larger and larger, which directly leads to the corresponding increase of the size of the power switching tube. The built-in power tube simplifies the design of the switching power supply, so that the switching power supply module becomes compact, but the large-sized power switching tube increases the design cost and the manufacturing cost.

Disclosure of Invention

The embodiment of the application provides a control method, a control circuit and a switching power supply of a power switch tube, which can solve the problem that the design cost and the manufacturing cost are increased due to the adoption of a large-size power switch tube in a switching power supply chip.

In a first aspect, an embodiment of the present application provides a method for controlling a power switch tube, including:

when an opening signal of the power switching tube is received, an opening control signal for controlling the opening of the first power switching tube and the second power switching tube is generated according to the current feedback signal;

The starting control signals are respectively sent to a driving delay control circuit and a first driving circuit of the first power switching tube, so that the first driving circuit outputs a first driving current signal according to the starting control signals to control the first power switching tube to be started;

After the first power switch tube is started for a preset time period, the driving delay control circuit sends the starting control signal to a second driving circuit of the second power switch tube, so that the second driving circuit outputs a second driving current signal according to the starting control signal to control the second power switch tube to be started;

The first power switch tube is an external chip sealing power tube, the second power switch tube is an internal chip power tube, and the current of the second power switch tube and the current of the first power switch tube are preset to be in a fixed current proportion.

In a possible implementation manner of the first aspect, after the generating, according to the current feedback signal, an on control signal for controlling the first power switch tube and the second power switch tube, the method includes:

sampling the current flowing through the second power switch tube through a sampling resistor to obtain a current sampling voltage;

And comparing the current sampling voltage with a preset peak current limiting voltage and a current limiting voltage through a current control module to obtain the current feedback signal so as to limit the current flowing through the first power switch tube according to the current feedback signal, wherein the current limiting voltage is generated according to the voltage feedback signal through the voltage control module.

In a possible implementation manner of the first aspect, the comparing, by the current control module, the current sampling voltage with a preset peak current limiting voltage and a current limiting voltage to obtain the current feedback signal includes:

When the current sampling voltage is smaller than the preset peak current limiting voltage and the current sampling voltage is smaller than the current limiting voltage, the current feedback signal is a first logic signal to generate the starting control signal for controlling the first power switching tube and the second power switching tube to be started according to the first logic signal, wherein the first logic signal is used for representing that the current flowing through the first power switching tube and the second power switching tube is smaller than a preset current threshold value;

And when the current sampling voltage is greater than or equal to the preset peak current limiting voltage, or when the current sampling voltage is greater than or equal to the current limiting voltage, the current feedback signal is a second logic signal so as to generate a closing control signal for controlling the first power switching tube and the second power switching tube to be closed according to the second logic signal, wherein the second logic signal is used for representing that the current flowing through the first power switching tube and the second power switching tube is greater than or equal to the preset current threshold value.

In a possible implementation manner of the first aspect, the method includes:

And when the driving circuit receives the closing control signal sent by the signal control circuit, the first power switching tube and the second power switching tube are simultaneously closed according to the closing control signal.

In a second aspect, an embodiment of the present application provides a control circuit for a power switch tube, where the control circuit executes the control method for a power switch tube according to any one of the first aspect, and the control circuit includes a first power switch tube, a second power switch tube, a signal control circuit, a first driving circuit, a second driving circuit, a driving delay control circuit, a voltage control module, a sampling resistor and a current control module, where the first power switch tube is a power switch tube with an external chip and a power switch tube with an internal chip;

The signal control circuit is used for generating an opening control signal for controlling the first power switch tube and the second power switch tube to be opened according to a current feedback signal, and the signal control circuit is used for respectively transmitting the opening control signal to the driving delay control circuit and the first driving circuit of the first power switch tube;

the first driving circuit is connected in series with the signal control circuit and is used for receiving the starting control signal sent by the signal control circuit and outputting a first driving current signal according to the starting control signal so as to control the starting of the first power switch tube;

The driving delay control circuit is connected in series with the signal control circuit and is used for receiving the starting control signal sent by the signal control circuit and sending the starting control signal to the second driving circuit of the second power switch tube after the first power switch tube is started for the preset time period;

the second driving circuit is connected in series with the driving delay control circuit and is used for receiving the starting control signal sent by the driving delay control circuit and outputting a second driving current signal according to the starting control signal so as to control the second power switch tube to be started;

the voltage control module is used for generating a current limiting voltage according to a voltage feedback signal and inputting the current limiting voltage into the current control module;

the sampling resistor is connected in series with the second power switch tube and is used for converting the current flowing through the second power switch tube into a current sampling voltage;

The current control module is connected in series with the signal control circuit, the second power switch tube and the voltage control module and is used for generating the current feedback signal according to the current sampling voltage, the preset peak current limiting voltage and the current limiting voltage so as to limit the current flowing through the first power switch tube according to the current feedback signal.

In a possible implementation manner of the second aspect, a first output end of the signal control circuit is connected to an input end of the first driving circuit, and an output end of the first driving circuit is connected to a first gate of the first power switch tube;

The second output end of the signal control circuit is connected with the input end of the second driving circuit through the driving delay control circuit, and the output end of the second driving circuit is connected with the second grid electrode of the second power switch tube;

The first drain electrode of the first power switch tube is connected with the second drain electrode of the second power switch tube;

The second source electrode of the second power switch tube is connected with the input end of the current control module, the second source electrode of the second power switch tube is connected with the first source electrode of the first power switch tube after being connected with the sampling resistor in series, and the first source electrode of the first power switch tube is connected with the current output end of the switch power supply chip.

In a possible implementation manner of the second aspect, the driving delay control circuit includes a first logic inverter, a second logic inverter, a third logic inverter, a nor gate, a first resistor and a first capacitor, where,

The first logic inverter is connected with the first input end of the NOR gate in series through the second logic inverter, the first resistor and the third logic inverter;

the first logic inverter is connected with the second input end of the NOR gate;

the input end of the first capacitor is connected with the first resistor, and the output end of the first capacitor is grounded.

In a possible implementation manner of the second aspect, the size of the first power switch tube is larger than the size of the second power switch tube.

In a possible implementation manner of the second aspect, the lengths of the first power switch tube and the second power switch tube are equal, and the width of the first power switch tube is an integer multiple of the width of the second power switch tube.

In a third aspect, an embodiment of the present application provides a switching power supply, where the switching power supply includes a control circuit of a power switching tube according to any one of the second aspects, and the control circuit of the power switching tube performs the control method of the power switching tube according to any one of the first aspects.

In a fourth aspect, an embodiment of the present application provides a control device for a power switching tube, where the device includes:

The starting signal generation module is used for generating starting control signals for controlling the first power switch tube and the second power switch tube to be started according to the current feedback signals when the starting signals of the power switch tubes are received;

The power switch comprises a first power switch tube, a second power switch tube, a start signal output module, a drive delay control circuit and a second power switch tube, wherein the first power switch tube is connected with the first power switch tube, the second power switch tube is connected with the first power switch tube, the first power switch tube is connected with the second power switch tube, the first power switch tube is connected with the first power switch tube, the second power switch tube is connected with the second power switch tube, and the second power switch tube is connected with the first power switch tube;

Compared with the prior art, the embodiment of the application has the beneficial effects that:

The control method of the power switch tube comprises the steps of generating starting control signals for controlling the first power switch tube and the second power switch tube to be started according to current feedback signals when starting signals of the power switch tube are received, respectively sending the starting control signals to a driving delay control circuit and a first driving circuit of the first power switch tube, enabling the first driving circuit to output a first driving current signal according to the starting control signals, controlling the first power switch tube to be started, and after the first power switch tube is started for a preset time period, enabling the driving delay control circuit to send the starting control signals to a second driving circuit of the second power switch tube, enabling the second driving circuit to output a second driving current signal according to the starting control signals, and controlling the second power switch tube to be started, wherein the first power switch tube is a chip-mounted combined power switch tube, the second power switch tube is a chip-built-in power tube, and the current of the second power switch tube and the current of the first power switch tube are preset to be in a fixed current proportion. The power switch tube is turned on by using the external sealing power tube and the internal power tube in the switch power supply chip and by a control method of the power switch tube, so that the problems of high design cost and manufacturing cost caused by the adoption of a large-size power switch tube in the switch power supply chip are solved.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the embodiments or the description of the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and that other drawings can be obtained according to these drawings without inventive effort for a person skilled in the art.

Fig. 1 is a schematic circuit diagram of a step-down switching power supply in the prior art according to the present application;

fig. 2 is a schematic flow chart of a control method of a power switch tube according to an embodiment of the application;

fig. 3 is a schematic circuit diagram of a control circuit of a power switch tube according to an embodiment of the present application;

FIG. 4 is a schematic diagram of a circuit structure of a driving delay control circuit according to an embodiment of the present application;

FIG. 5 is a schematic diagram of a timing waveform of a first power switch and a second power switch according to an embodiment of the present application;

Fig. 6 is a schematic structural diagram of a switching power supply according to an embodiment of the present application;

fig. 7 is a schematic structural diagram of a control device for a power switch tube according to an embodiment of the present application.

Detailed Description

In the following description, for purposes of explanation and not limitation, specific details are set forth such as the particular system architecture, techniques, etc., in order to provide a thorough understanding of the embodiments of the present application. It will be apparent, however, to one skilled in the art that the present application may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present application with unnecessary detail.

It should be understood that the terms "comprises" and/or "comprising," when used in this specification and the appended claims, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

It should also be understood that the term "and/or" as used in the present specification and the appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes such combinations.

As used in the present description and the appended claims, the term "if" may be interpreted as "when..once" or "in response to a determination" or "in response to detection" depending on the context. Similarly, the phrase "if a determination" or "if a [ described condition or event ] is detected" may be interpreted in the context of meaning "upon determination" or "in response to determination" or "upon detection of a [ described condition or event ]" or "in response to detection of a [ described condition or event ]".

Furthermore, the terms "first," "second," "third," and the like in the description of the present specification and in the appended claims, are used for distinguishing between descriptions and not necessarily for indicating or implying a relative importance.

Reference in the specification to "one embodiment" or "some embodiments" or the like means that a particular feature, structure, or characteristic described in connection with the embodiment is included in one or more embodiments of the application. Thus, appearances of the phrases "in one embodiment," "in some embodiments," "in other embodiments," and the like in the specification are not necessarily all referring to the same embodiment, but mean "one or more but not all embodiments" unless expressly specified otherwise. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless expressly specified otherwise.

As shown in fig. 1, fig. 1 is a schematic circuit diagram of a step-down switching power supply in the prior art according to the present application. As shown in fig. 1, the circuit of the buck switching power supply comprises a control circuit, a driving circuit, a power switching tube M, a sampling resistor R, a voltage control module, a current control module, an inductor L0, an output end filter capacitor C0 and a freewheeling diode D0, wherein the inductor L0 is used for storing energy, and the freewheeling diode D0 is used for being conducted when the power switching tube M is turned off. Wherein Vin is a voltage input end of the power switch tube M, vout is a direct-current voltage output end, OUT0 represents a current output end of the switch power supply chip, VFB0 represents a voltage feedback signal, vcs0 represents a current sampling voltage, VC0 represents a current limiting voltage, and Vref0 represents a preset peak current limiting voltage.

The BUCK switching power supply is a switching power supply adopting a BUCK converter topology structure, and the input direct-current voltage is reduced to a lower and stable direct-current voltage for output by periodically turning on and off one or more power switching tubes. In fig. 1, in the circuit of the buck switching power supply, a power switching tube M is a chip built-in power tube. However, as the power requirement of the switching power supply increases, the current requirement on the power switching tube is larger and larger, the built-in power tube of the chip is limited by the physical size and the manufacturing process, and cannot bear high current load, so that the power supply cannot work normally, and the size of the power switching tube also needs to be increased correspondingly. But large size power switching tubes increase design and manufacturing costs. Therefore, the embodiment of the application provides a control circuit of a power switch tube to solve the problem that the design cost and the manufacturing cost are increased due to the adoption of a large-size power switch tube in a switch power supply.

Referring to fig. 2, fig. 2 is a flow chart of a control method of a power switch tube according to an embodiment of the application. The control method of the power switch tube comprises the following steps:

S11, when an opening signal of the power switch tube is received, an opening control signal for controlling the opening of the first power switch tube and the second power switch tube is generated according to the current feedback signal;

s12, respectively sending an opening control signal to a driving delay control circuit and a first driving circuit of the first power switching tube so that the first driving circuit outputs a first driving current signal according to the opening control signal to control the first power switching tube to be opened;

after the first power switch tube is started for a preset time period, the driving delay control circuit sends a starting control signal to a second driving circuit of the second power switch tube, so that the second driving circuit outputs a second driving current signal according to the starting control signal to control the second power switch tube to be started;

It should be noted that, in general, the on signal of the power switch tube is a signal representing the on of the power switch tube output by the current control module when each on clock of the power switch tube arrives. The current feedback signal is a signal which is processed by the current control module and fed back to the signal control circuit, namely, a signal generated by the current control module according to the current sampling voltage, the preset peak current limiting voltage and the current limiting voltage. The starting control signal is generated by a signal control circuit according to the current feedback signal and is used for controlling the starting of the first power switching tube and the second power switching tube. The first driving current signal is a current signal which is generated by the first driving circuit according to the opening control signal and drives the first power switch tube to be converted from the closed state to the open state, and the second driving current signal is a current signal which is generated by the second driving circuit according to the opening control signal and drives the second power switch tube to be converted from the closed state to the open state. The driving delay control circuit is used for sending an opening control signal to the second driving circuit after the first power switch tube is opened for a preset time period, so that the second driving circuit controls the second power switch tube to be opened. In the embodiment, the first power switch tube and the second power switch tube respectively adopt respective driving circuits, namely a first driving circuit and a second driving circuit, and the circuit structures of the first driving circuit and the second driving circuit are the same. The preset time period is a preset delay time, and is not particularly limited.

The method comprises the steps of generating opening control signals for controlling the first power switch tube and the second power switch tube to be opened according to current feedback signals, then respectively sending the opening control signals to a driving delay control circuit and a first driving circuit of the first power switch tube, at the moment, the first driving circuit outputs a first driving current signal according to the opening control signals, controlling the first power switch tube to be opened through the first driving current signal, and then delaying the starting control signals for a preset time period through the driving delay control circuit, namely, after the first power switch tube is opened for the preset time period, sending the opening control signals to a second driving circuit of the second power switch tube by the driving delay control circuit, outputting a second driving current signal according to the opening control signals, and controlling the second power switch tube to be opened through the second driving current signal, so that the opening of the first power switch tube is earlier than the opening of the second power switch tube.

In this embodiment, since the threshold voltage of the built-in power switch tube is lower than that of the external power switch tube, the first driving circuit turns on the first power switch tube first, and then, after a preset period of time, the second driving circuit turns on the second power switch tube, so that the time delay of turning on the power switch tube can be shortened. The starting time requirement of the preset time period is set through the driving delay control circuit, so that the starting sequence and the time interval of the first power switch tube and the second power switch tube can be accurately controlled.

It should be noted that the first power switch tube is a power tube with an external chip and a sealed power tube, which is mainly used for high-current switch, and can be a customized MOS power tube, and the second power switch tube is a power tube with an internal chip, and can also be a MOS power tube. And presetting the current of the second power switch tube and the current of the first power switch tube to be in a fixed current proportion. In this embodiment, the fixed current ratio is not particularly limited. The first power switch tube is an external power tube, the controller, the power switch tube and the like are integrated together through a sealing technology, the integration level of the chip can be improved, the size is reduced, the number of components is reduced, the design complexity is reduced, and therefore the design cost and the manufacturing cost are reduced.

It can be appreciated that the control method of the power switch tube provided by the embodiment of the application comprises the steps of generating an opening control signal for controlling the opening of the first power switch tube and the second power switch tube according to a current feedback signal when the opening signal of the power switch tube is received, respectively sending the opening control signal to a driving delay control circuit and a first driving circuit of the first power switch tube so that the first driving circuit outputs a first driving current signal according to the opening control signal to control the opening of the first power switch tube, and after the first power switch tube is opened for a preset time period, sending the opening control signal to a second driving circuit of the second power switch tube so that the second driving circuit outputs a second driving current signal according to the opening control signal to control the opening of the second power switch tube, wherein the first power switch tube is a chip external sealing power tube, the second power switch tube is a chip built-in power tube, and the current of the second power switch tube and the current of the first power switch tube are preset to be in a fixed current proportion. The power switch tube is turned on by using the external sealing power tube and the internal power tube in the switch power supply chip and by a control method of the power switch tube, so that the problems of high design cost and manufacturing cost caused by the adoption of a large-size power switch tube in the switch power supply chip are solved.

In one possible implementation manner, after generating the on control signals for controlling the first power switch tube and the second power switch tube according to the current feedback signals, the control method of the power switch tube includes:

And comparing the current sampling voltage with a preset peak current limiting voltage and a current limiting voltage through a current control module to obtain a current feedback signal so as to limit the current flowing through the first power switch tube according to the current feedback signal, wherein the current limiting voltage is generated according to the voltage feedback signal through the voltage control module.

Specifically, a sampling resistor is connected in series with the second power switch tube, and the sampling resistor is used for converting the current flowing through the second power switch tube into a current sampling voltage. The current control module is connected in series with the signal control circuit and the second power switch tube, and is used for comparing the current sampling voltage with a preset peak current limiting voltage and a preset current limiting voltage to generate a current feedback signal, and then limiting the current flowing through the first power switch tube according to the current feedback signal. The current control module may be a current limiting comparator, and in this embodiment, the current control module is not specifically limited.

The current sampling voltage is obtained by converting the current flowing through the second power switch tube into voltage through a sampling resistor. The preset peak current limiting voltage is a preset reference voltage threshold value and is used for comparing with the current sampling voltage so as to judge whether the current exceeds a safety range or not. And comparing the current sampling voltage with a preset peak current limiting voltage and a current limiting voltage through a current control module, so as to obtain a current feedback signal.

The current limited voltage is generated by a voltage control module from a voltage feedback signal. The voltage feedback signal is a signal that the voltage of the output end is fed back to the switching power supply chip through resistor voltage division in the switching power supply chip. That is, the voltage control module adjusts the magnitude of the current limiting voltage according to the voltage feedback signal and outputs the current limiting voltage to the current control module, so as to maintain the stability of the output voltage of the switching power supply chip.

In one possible implementation manner, comparing, by the current control module, the current sampling voltage with a preset peak current limiting voltage and a current limiting voltage to obtain a current feedback signal, including:

When the current sampling voltage is smaller than a preset peak current limiting voltage and the current sampling voltage is smaller than the current limiting voltage, the current feedback signal is a first logic signal to generate an opening control signal for controlling the first power switching tube and the second power switching tube to be opened according to the first logic signal, wherein the first logic signal is used for representing that the current flowing through the first power switching tube and the second power switching tube is smaller than a preset current threshold value;

When the current sampling voltage is greater than or equal to a preset peak current limiting voltage, or when the current sampling voltage is greater than or equal to the current limiting voltage, the current feedback signal is a second logic signal, so as to generate a closing control signal for controlling the first power switching tube and the second power switching tube to be closed according to the second logic signal, wherein the second logic signal is used for representing that the current flowing through the first power switching tube and the second power switching tube is greater than or equal to a preset current threshold value.

Specifically, when the current sampling voltage is smaller than a preset peak current limiting voltage and the current sampling voltage is smaller than the current limiting voltage, the current control module outputs a current feedback signal representing that the current in the power switch tube is smaller than a preset current threshold, namely a first logic signal, so that the signal control circuit generates an opening control signal for controlling the opening of the first power switch tube and the second power switch tube according to the first logic signal, the opening control signal represents that the current in the power switch tube is in a safe range at the moment, the first power switch tube and the second power switch tube can be opened, and when the current sampling voltage is larger than or equal to the preset peak current limiting voltage or when the current sampling voltage is larger than or equal to the current limiting voltage, the current control module outputs a current feedback signal representing that the current in the power switch tube is larger than or equal to the preset current threshold, namely a second logic signal, the signal is generated by the signal control circuit, the signal control circuit generates a closing control signal for controlling the first power switch tube and the second power switch tube according to the second logic signal, the closing control signal represents that the current in the power switch tube exceeds the safe range at the moment, the first power switch tube and the second power switch tube needs to be closed, and the current in the power switch tube is prevented from being further increased, and possible damage to equipment is caused. The preset current threshold is a preset specification value of the maximum current that can flow through the power switch tube, namely the maximum safe current allowed to pass through the power switch Guan Zhongyun. The current control module is used for limiting the current flowing through the first power switch tube, so that equipment damage possibly caused by overlarge current can be prevented.

In one possible implementation manner, the control method of the power switch tube comprises the following steps:

when the driving circuit receives the closing control signal sent by the signal control circuit, the first power switch tube and the second power switch tube are closed at the same time according to the closing control signal.

When the signal control circuit outputs the closing control signal, the driving delay control circuit does not play a role in delay at the moment, and the first power switch tube and the second power switch tube are closed at the same time according to the closing control signal.

It is understood that the voltage control module generates the current limiting voltage required by the current control module based on the voltage feedback signal. The current control module outputs a signal representing the on or off of the power switch tube to the signal control circuit according to the input current limiting voltage, the preset peak current limiting voltage and the current sampling voltage acquired by the sampling resistor, if the current control module outputs an on signal representing the on of the power switch tube, the signal control circuit sends an on control signal representing the on of the power switch tube to the driving circuit when each on clock arrives, the driving circuit controls the first power switch tube to be on, after the first power switch tube is controlled to be on for a preset time period, the second power switch tube is controlled to be on, as the output current of the switch power supply chip is increased, the current sampling voltage on the sampling resistor is increased until the current control module outputs a signal representing the off of the power switch tube to the signal control circuit, and the signal control circuit outputs an off control signal to close the first power switch tube and the second power switch tube through the driving circuit. The output current of the switching power supply chip is reduced, and the current control module outputs an opening signal representing the opening of the power tube to the signal control circuit. The signal control circuit repeats the above operation when the next on-clock arrives.

It should be understood that the sequence number of each step in the foregoing embodiment does not mean that the execution sequence of each process should be determined by the function and the internal logic, and should not limit the implementation process of the embodiment of the present application.

Referring to fig. 3, fig. 3 is a schematic circuit diagram of a control circuit of a power switch according to an embodiment of the application. The control circuit 1 of the power switching tube executes the control method of the power switching tube according to any one of the above, and the control circuit 1 of the power switching tube includes:

The power supply circuit comprises a first power switch tube M1, a second power switch tube M2, a signal control circuit 10, a first driving circuit 21, a second driving circuit 22, a driving delay control circuit 23, a voltage control module 40, a sampling resistor Rs and a current control module 30, wherein the first power switch tube M1 is an external chip sealing power tube, and the second power switch tube M2 is an internal chip power tube;

The signal control circuit 10 is used for generating an opening control signal for controlling the opening of the first power switch tube M1 and the second power switch tube M2 according to the current feedback signal, and is used for respectively transmitting the opening control signal to the driving delay control circuit 23 and the first driving circuit 21 of the first power switch tube M1, wherein the first driving circuit 21 is connected with the signal control circuit 10 in series and is used for receiving the opening control signal transmitted by the signal control circuit 10 and outputting a first driving current signal according to the opening control signal so as to control the opening of the first power switch tube M1;

A driving delay control circuit 23 connected in series with the signal control circuit 10 and configured to receive the on control signal sent by the signal control circuit 10, and send the on control signal to the second driving circuit 22 of the second power switch tube M2 after the first power switch tube M1 is turned on for a preset period of time;

the second driving circuit 22 is connected in series with the driving delay control circuit 23, and is used for receiving the start control signal sent by the driving delay control circuit 23 and outputting a second driving current signal according to the start control signal so as to control the second power switch tube M2 to be started;

A voltage control module 40 for generating a current limiting voltage VC according to the voltage feedback signal VFB and inputting the current limiting voltage VC to the current control module 30;

the sampling resistor Rs is connected in series with the second power switch tube M2 and is used for converting the current flowing through the second power switch tube M2 into a current sampling voltage Vcs;

The current control module 30 is connected in series with the signal control circuit 10, the second power switch tube M2, and the voltage control module 40, and is configured to generate a current feedback signal according to the current sampling voltage Vcs, the preset peak current limiting voltage Vref, and the current limiting voltage VC, so as to limit the current flowing through the first power switch tube M1 according to the current feedback signal.

As shown in fig. 3, the control circuit 1 of the power switch tube includes a first power switch tube M1, a second power switch tube M2, a signal control circuit 10, a first driving circuit 21, a second driving circuit 22, a driving delay control circuit 23, a voltage control module 40, a sampling resistor Rs, and a current control module 30. The power switch tube is a high-efficiency and high-reliability electronic element, generally refers to a transistor capable of bearing larger current and voltage, and is widely applied to circuits such as current conversion, amplification and switching in various electronic devices. The first power switch tube M1 is a power tube with an external chip and a sealed, is mainly used for high-current switch, and can be a customized MOS power tube, and the second power switch tube M2 is a power tube with an internal chip and can also be a MOS power tube. Since the characteristics of the first power switch tube M1 and the second power switch tube M2 are different, the current of the second power switch tube M2 and the current of the first power switch tube M1 are preset to be a fixed current proportion, and in this embodiment, the fixed current proportion is not specifically limited. The first power switch tube M1 is an external chip sealing power tube, and integrates the controller, the power switch tube and the like together through a sealing technology, so that the integration level of the chip can be improved, the size is reduced, the number of components is reduced, the design complexity is reduced, and the design cost and the manufacturing cost are reduced. In fig. 3, vin is a voltage input terminal of a power switch tube, OUT1 is a current output terminal of a switch power supply chip, vref represents a preset peak current limiting voltage, vcs represents a current sampling voltage, VFB represents a voltage feedback signal, and VC represents a current limiting voltage.

Specifically, the signal control circuit 10 is connected in series with the first driving circuit 21 and the current control module 30, and the signal control circuit 10 is also connected in series with the driving delay control circuit 23, for generating an on control signal for controlling the first power switching transistor M1 and the second power switching transistor M2 to be turned on according to the current feedback signal, and for transmitting the on control signal to the driving delay control circuit 23 and the first driving circuit 21 of the first power switching transistor M1, respectively. The current feedback signal is a signal processed by the current control module 30 and fed back to the signal control circuit 10, that is, a signal generated by the current control module according to the current sampling voltage Vcs, the preset peak current limiting voltage Vref and the current limiting voltage VC. The turn-on control signal is generated by the signal control circuit 10 according to the current feedback signal, and is used for controlling the turn-on signals of the first power switch tube M1 and the second power switch tube M2. Then, at each initial stage of turning on the power switch tube, the signal control circuit 10 inputs the outputted turn-on control signals to the driving delay control circuit 23 and the first driving circuit 21 of the first power switch tube M1 respectively, then the first driving circuit 21 controls the first power switch tube M1 to turn on, at this time, the control signal outputted by the signal control circuit 10 is inputted to the driving delay control circuit 23 first, and after a delay of a preset period of time, inputted to the second driving circuit 22 of the second power switch tube M2, and controls the second power switch tube M2 to turn on, so that the turn-on of the first power switch tube M1 precedes the turn-on of the second power switch tube M2. The preset time period is a preset delay time, and is not particularly limited in this embodiment.

The first driving circuit 21 is connected in series with the signal control circuit 10, the driving delay control circuit 23 is connected in series with the signal control circuit 10, and the second driving circuit 22 is connected in series with the driving delay control circuit 23. The first driving circuit 21 receives the on control signal sent by the signal control circuit 10, and outputs a first driving current signal according to the on control signal to control the first power switch tube M1 to be turned on. The driving delay control circuit 23 receives the start control signal sent by the signal control circuit 10, then sends the start control signal to the second driving circuit 22 of the second power switch tube M2 after the first power switch tube M1 is started for a preset period of time, and the second driving circuit 22 receives the start control signal sent by the driving delay control circuit 23, and then outputs a second driving current signal according to the start control signal to control the second power switch tube M2 to be started. The first driving current signal is a current signal generated by the first driving circuit 21 according to an on control signal and used for driving the first power switch tube M1 to be turned into an on state from an off state, and the second driving current signal is a current signal generated by the second driving circuit 22 according to an on control signal and used for driving the second power switch tube M2 to be turned into an on state from an off state. In this embodiment, the first power switch tube M1 and the second power switch tube M2 respectively adopt respective driving circuits, namely a first driving circuit 21 and a second driving circuit 22, and the circuit structures of the first driving circuit 21 and the second driving circuit 22 are the same.

The voltage control module 40 is connected to the current control module 30, and is configured to generate a current limiting voltage VC according to the voltage feedback signal VFB, and input the current limiting voltage VC into the current control module 30. The voltage feedback signal VFB is a signal that is fed back to the switching power supply chip by voltage division of the voltage at the output terminal through a resistor. That is, the voltage control module 40 adjusts the magnitude of the current limiting voltage VC according to the voltage feedback signal VFB and outputs the current limiting voltage VC to the current control module 30, so as to maintain the stability of the output voltage of the switching power supply chip.

The sampling resistor Rs is connected in series with the second power switch tube M2, and the sampling resistor Rs is used for converting the current flowing through the second power switch tube M2 into a current sampling voltage. The current control module 30 is connected in series with the signal control circuit 10, the second power switch tube M2, and the voltage control module 40, and the current control module 30 is configured to generate a current feedback signal according to the current sampling voltage Vcs, the preset peak current limiting voltage Vref, and the current limiting voltage VC, so as to limit the current flowing through the first power switch tube M1 according to the current feedback signal. The current sampling voltage is obtained by converting the current flowing through the second power switch tube M2 into voltage through a sampling resistor Rs. The preset peak current limit voltage is a preset reference voltage threshold for comparing with the current sampling voltage Vcs to determine whether the current exceeds the safety range. The current control module 30 may be a current limiting comparator, and the current control module 30 is not particularly limited in this embodiment.

The current feedback signal is a feedback signal obtained by sampling the current flowing through the second power switch tube M2 through the sampling resistor Rs to obtain a current sampling voltage Vcs, and then comparing the current sampling voltage Vcs with a preset peak current limiting voltage Vref and a preset current limiting voltage VC through the current control module 30. When the current sampling voltage Vcs is smaller than the preset peak current limiting voltage Vref and the current sampling voltage Vcs is smaller than the current limiting voltage VC, the current control module 30 outputs a current feedback signal indicating that the current in the power switch tube is smaller than the preset current threshold value, so as to generate an on control signal for controlling the first power switch tube M1 and the second power switch tube M2 to be turned on according to the current feedback signal, and when the current sampling voltage Vcs is greater than or equal to the preset peak current limiting voltage Vref or when the current sampling voltage Vcs is greater than or equal to the current limiting voltage VC, the current control module 30 outputs a current feedback signal indicating that the current in the power switch tube is greater than or equal to the preset current threshold value, so as to generate an off control signal for controlling the first power switch tube M1 and the second power switch tube M2 to be turned off according to the current feedback signal.

Specifically, the current sampling voltage Vcs is obtained from a sampling resistor Rs connected in series with the second source of the second power switching transistor M2. The current sampling voltage Vcs, the preset peak current limiting voltage Vref and the current limiting voltage VC are input into the current control module 30 for comparison, the current control module 30 outputs a logic signal representing the comparison result, finally, the logic signal is input into the signal control circuit 10, and the signal control circuit 10 outputs an on control signal or an off control signal to realize the control of the on or off of the power switch tube. In this embodiment, since the widths of the first power switch tube M1 and the second power switch tube M2 are proportional, as known from the square rate formula of the power switch tubes, the currents flowing through the first power switch tube M1 and the second power switch tube M2 are also proportional, and thus the total current flowing through the first power switch tube M1 and the second power switch tube M2 can be detected by detecting the current flowing through the first power switch tube M1 through the sampling resistor Rs, thereby achieving the purpose of controlling the output current of the switching power supply. The square rate formula of the power switch tube is as follows:

;

In the above formula, I _DS represents a drain-source current flowing through the power switching tube, K _p represents a process parameter of the power switching tube, W represents a width of the power switching tube, L represents a length of the power switching tube, V _GS represents a gate-to-source voltage of the power switching tube, and V _TH represents a threshold voltage of the power switching tube.

It can be understood that the control circuit 1 of the power switch tube provided by the embodiment of the application comprises a first power switch tube M1, a second power switch tube M2, a signal control circuit 10, a first driving circuit 21, a second driving circuit 22, a driving delay control circuit 23, a voltage control module 40, a sampling resistor Rs and a current control module 30, wherein the first power switch tube M1 is an external-chip sealed power tube, the second power switch tube M2 is an internal-chip power tube, the current of the second power switch tube M2 and the current of the first power switch tube M1 are preset to be a fixed current ratio, the signal control circuit 10 is used for generating an opening control signal for controlling the opening of the first power switch tube M1 and the second power switch tube M2 according to a current feedback signal, and is used for respectively transmitting the opening control signal to the first driving delay control circuit 23 and the first driving circuit 21 of the first power switch tube M1, the first driving circuit 21 is connected in series with the signal control circuit 10, is used for receiving the opening control signal transmitted by the signal control circuit 10, the second power switch tube M2 is connected in series with the signal control circuit 23 and is used for transmitting the opening control signal to the first delay control circuit 23 according to the preset current of the first power switch tube M1, the second driving delay control circuit 2 is connected in series, the second driving circuit is used for transmitting the opening control signal to the first delay control signal is used for controlling the opening of the first power switch tube M2, and the second driving circuit is controlled to be opened according to the first drive delay control circuit 23, and the first drive signal is connected to the first drive circuit is connected to the first and the first drive circuit 1, the voltage control module 40 is used for generating a current limiting voltage VC according to a voltage feedback signal VFB and inputting the current limiting voltage VC to the current control module 30, the sampling resistor Rs is connected in series with the second power switch tube M2 and used for converting the current flowing through the second power switch tube M2 into a current sampling voltage Vcs, and the current control module 30 is connected in series with the signal control circuit 10, the second power switch tube M2 and the voltage control module 40 and used for generating a current feedback signal according to the current sampling voltage Vcs, a preset peak current limiting voltage Vref and the current limiting voltage VC so as to limit the current flowing through the first power switch tube M1 according to the current feedback signal. The problem that design cost and manufacturing cost are increased due to the fact that a large-size power switch tube is adopted in a switch power supply chip is solved by using a chip external sealing power tube and a chip internal power tube in the switch power supply chip.

In one possible implementation, the first output terminal of the signal control circuit 10 is connected to the input terminal of the first driving circuit 21, and the output terminal of the first driving circuit 21 is connected to the first gate of the first power switching transistor M1;

The second output end of the signal control circuit 10 is connected with the input end of the second driving circuit 22 through the driving delay control circuit 23, and the output end of the second driving circuit 22 is connected with the second grid electrode of the second power switch tube M2;

the first drain electrode of the first power switch tube M1 is connected with the second drain electrode of the second power switch tube M2;

The second source electrode of the second power switch tube M2 is connected with the input end of the current control module 30, the second source electrode of the second power switch tube M2 is connected with the first source electrode of the first power switch tube M1 after being connected with the sampling resistor Rs in series, and the first source electrode of the first power switch tube M1 is connected with the current output end of the switch power supply chip.

Specifically, as shown in fig. 3, a first output end of the signal control circuit 10 is connected to an input end of the first driving circuit 21, an output end of the first driving circuit 21 is connected to a first gate of the first power switch tube M1, a second output end of the signal control circuit 10 is connected to an input end of the second driving circuit 22 through the driving delay control circuit 23, an output end of the second driving circuit 22 is connected to a second gate of the second power switch tube M2, a first drain electrode of the first power switch tube M1 is connected to a second drain electrode of the second power switch tube M2, a second source electrode of the second power switch tube M2 is connected to an input end of the current control module 30, a second source electrode of the second power switch tube M2 is connected to a first source electrode of the first power switch tube M1 after being connected in series with the sampling resistor Rs, and a first source electrode of the first power switch tube M1 is connected to a current output end of the switching power supply chip.

In the present embodiment, the first power switch tube M1 and the second power switch tube M2 respectively adopt respective driving circuits, that is, the first driving circuit 21 and the second driving circuit 22, and the circuit structures of the first driving circuit 21 and the second driving circuit 22 are the same. The signal control circuit 10 inputs the output start control signal to the drive delay control circuit 23 and the first driving circuit 21 of the first power switch tube M1, then the first driving circuit 21 controls the first power switch tube M1 to start, at this time, the control signal output by the signal control circuit 10 is input to the drive delay control circuit 23 first, after a delay of a preset period of time, is input to the second driving circuit 22 of the second power switch tube M2, and controls the second power switch tube M2 to start, so that the first power switch tube M1 starts before the second power switch tube M2. In this embodiment, since the threshold voltage of the built-in power switch tube is lower than that of the external power switch tube, the first driving circuit 21 turns on the first power switch tube M1 first, and then, after a preset time, the second driving circuit 22 turns on the second power switch tube M2 again, so that the time delay of turning on the power switch tube can be shortened.

In one possible implementation, the driving delay control circuit 23 includes a first logic inverter INV1, a second logic inverter INV2, a third logic inverter INV3, a NOR gate NOR2, a first resistor R1 and a first capacitor C1, wherein,

The first logic inverter INV1 is connected in series with the first input end of the NOR gate NOR2 through the second logic inverter INV2, the first resistor R1 and the third logic inverter INV 3;

the first logic inverter INV1 is connected with the second input end of the NOR gate NOR 2;

The input end of the first capacitor C1 is connected with the first resistor R1, and the output end of the first capacitor C1 is grounded.

Please refer to fig. 4, fig. 4 is a schematic circuit diagram illustrating a driving delay control circuit according to an embodiment of the present application. As shown in fig. 4, the driving delay control circuit 23 is configured to send an on control signal to the second driving circuit 22 after the first power switch M1 is turned on for a preset period of time, so that the second driving circuit 22 controls the second power switch M2 to be turned on. The driving delay control circuit 23 includes a first logic inverter INV1, a second logic inverter INV2, a third logic inverter INV3, a NOR gate NOR2, a first resistor R1 and a first capacitor C1, wherein the first logic inverter INV1 is connected in series with a first input terminal of the NOR gate NOR2 through the second logic inverter INV2, the first resistor R1 and the third logic inverter INV3, the first logic inverter INV1 is connected with a second input terminal of the NOR gate NOR2, an input terminal of the first capacitor C1 is connected with the first resistor R1, and an output terminal of the first capacitor C1 is grounded. Wherein the IN terminal represents a signal input terminal of the drive delay control circuit 23, and the OUT terminal represents a signal output terminal of the drive delay control circuit 23. Logic inverters and nor gates are two basic logic elements in digital logic circuits. The nor gate is a composite logic gate circuit which performs a logical or operation on an input signal and then performs a logical inversion on the result.

Specifically, after an on control signal indicating that the power switch tube is turned on is input to the IN end of the driving delay control circuit 23, the second logic inverter INV2 IN the driving delay control circuit 23 charges a loop formed by the first resistor R1 and the first capacitor C1 to generate delay, and after a preset period of time, the OUT end of the driving delay control circuit 23 outputs the delayed on control signal and inputs the delayed on control signal to the second driving circuit 22.

When the signal control circuit 10 outputs the on control signal, the first power switch tube M1 is turned on by the first driving circuit 21, and at the same time, the second power switch tube M2 is turned on by the second driving circuit 22 after the driving delay control circuit 23 delays for a preset period of time. The preset time period of the delay can be adjusted by the driving delay control circuit 23.

Fig. 5 is a schematic diagram of timing waveforms of a first power switch tube and a second power switch tube according to an embodiment of the present application. In fig. 5, tdelay represents a delayed preset period, the first power switching transistor M1 is turned on at time T1, and after Tdelay time passes, the second power switching transistor M2 is turned on at time T2.

When the signal control circuit 10 outputs the off control signal, the driving delay control circuit 23 does not perform a delay function, and the first power switching transistor M1 and the second power switching transistor M2 are turned off at the same time.

In one possible implementation, the size of the first power switch tube M1 is larger than the size of the second power switch tube M2.

In one possible implementation, the lengths of the first power switch tube M1 and the second power switch tube M2 are equal, and the width of the first power switch tube is an integer multiple of the width of the second power switch tube M2.

It should be noted that, the first power switch tube M1 is an external power tube, and the second power switch tube M2 is a chip internal power tube. In this embodiment, the first power switch tube M1 may be a customized MOS power tube, and the second power switch tube M2 may be a MOS power tube. Because the first power switch tube M1 is mainly used as a high-current switch and is an external sealed high-size power tube, and the second power switch tube M2 is a chip built-in power tube, the size of the first power switch tube M1 is larger than that of the second power switch tube M2. Further, the lengths of the first power switch tube M1 and the second power switch tube M2 are equal, the width of the first power switch tube is an integer multiple of the width of the second power switch tube M2, and in this embodiment, the value range of the integer multiple may be 1-2000, and the specific value is not limited.

Referring to fig. 6, fig. 6 is a schematic structural diagram of a switching power supply according to an embodiment of the present application, the switching power supply 2 includes the control circuit 1 of the power switching tube according to any one of the above embodiments, and the control circuit 1 of the power switching tube performs the steps in the embodiment of the control method of the power switching tube according to any one of the above embodiments.

Fig. 7 is a schematic structural diagram of a control device for a power switch tube according to an embodiment of the present application. Referring to fig. 7, a control device 3 of a power switch tube of the embodiment includes:

the turn-on signal generating module 31 is configured to generate, according to the current feedback signal, an turn-on control signal for controlling the first power switching tube and the second power switching tube to be turned on when receiving the turn-on signal of the power switching tube;

The start signal output module 32 is configured to send start control signals to the drive delay control circuit and the first drive circuit of the first power switch tube, respectively, so that the first drive circuit outputs a first drive current signal according to the start control signal to control the first power switch tube to be turned on;

Further, the control device 3 of the power switching tube includes:

The current sampling module is used for sampling the current flowing through the second power switch tube through the sampling resistor to obtain a current sampling voltage;

The current feedback signal generation module is used for comparing the current sampling voltage with a preset peak current limiting voltage and a current limiting voltage through the current control module to obtain a current feedback signal so as to limit the current flowing through the first power switch tube according to the current feedback signal, wherein the current limiting voltage is generated according to the voltage feedback signal through the voltage control module.

Further, the current feedback signal generation module includes:

The first logic signal generation sub-module is used for generating an opening control signal for controlling the first power switch tube and the second power switch tube to be opened according to the first logic signal when the current sampling voltage is smaller than the preset peak current limiting voltage and the current sampling voltage is smaller than the current limiting voltage, wherein the first logic signal is used for representing that the current flowing through the first power switch tube and the second power switch tube is smaller than a preset current threshold value;

The second logic signal generation sub-module is used for generating a closing control signal for controlling the first power switch tube and the second power switch tube to be closed according to the second logic signal when the current sampling voltage is larger than or equal to a preset peak current limiting voltage or when the current sampling voltage is larger than or equal to the current limiting voltage, wherein the second logic signal is used for representing that the current flowing through the first power switch tube and the second power switch tube is larger than or equal to a preset current threshold value.

Further, the control device 3 of the power switching tube includes:

And the closing signal generation module is used for closing the first power switch tube and the second power switch tube according to the closing control signal when the driving circuit receives the closing control signal sent by the signal control circuit.

It should be noted that, because the content of information interaction and execution process between each module in the control device 3 of the power switch tube in the above embodiment is based on the same conception as the method embodiment of the present application, specific functions and technical effects thereof may be found in the method embodiment section, and will not be described herein.

The integrated units, if implemented in the form of software functional units and sold or used as stand-alone products, may be stored in a computer readable storage medium. Based on such understanding, the present application may implement all or part of the flow of the method of the above embodiments, and may be implemented by a computer program to instruct related hardware, where the computer program may be stored in a computer readable storage medium, and when the computer program is executed by a processor, the computer program may implement the steps of each of the method embodiments described above. Wherein the computer program comprises computer program code, which may be in the form of source code, object code, executable files or in some intermediate form, etc. The computer readable medium can include at least any entity or device capable of carrying computer program code to a camera device/terminal equipment, a recording medium, a computer Memory, a Read-Only Memory (ROM), a random access Memory (RAM, random Access Memory), an electrical carrier signal, a telecommunications signal, and a software distribution medium. Such as a U-disk, removable hard disk, magnetic or optical disk, etc. In some jurisdictions, computer readable media may not be electrical carrier signals and telecommunications signals in accordance with legislation and patent practice.

It will be apparent to those skilled in the art that, for convenience and brevity of description, only the above-described division of the functional units and modules is illustrated, and in practical application, the above-described functional distribution may be performed by different functional units and modules according to needs, i.e. the internal structure of the apparatus is divided into different functional units or modules to perform all or part of the above-described functions. The functional units and modules in the embodiment may be integrated in one processing unit, or each unit may exist alone physically, or two or more units may be integrated in one unit, where the integrated units may be implemented in a form of hardware or a form of a software functional unit. In addition, the specific names of the functional units and modules are only for distinguishing from each other, and are not used for limiting the protection scope of the present application. The specific working process of the units and modules in the above system may refer to the corresponding process in the foregoing method embodiment, which is not described herein again.

In the foregoing embodiments, the descriptions of the embodiments are emphasized, and in part, not described or illustrated in any particular embodiment, reference is made to the related descriptions of other embodiments.

Those of ordinary skill in the art will appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, or combinations of computer software and electronic hardware. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the solution. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present application.

In the embodiments provided in the present application, it should be understood that the disclosed apparatus/network device and method may be implemented in other manners. For example, the apparatus/network device embodiments described above are merely illustrative, e.g., the division of modules or elements is merely a logical functional division, and there may be additional divisions when actually implemented, e.g., multiple elements or components may be combined or integrated into another system, or some features may be omitted, or not performed. Alternatively, the coupling or direct coupling or communication connection shown or discussed may be an indirect coupling or communication connection via interfaces, devices or units, which may be in electrical, mechanical or other forms.

The units described as separate units may or may not be physically separate, and units shown as units may or may not be physical units, may be located in one place, or may be distributed over a plurality of network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

The foregoing embodiments are merely for illustrating the technical solution of the present application, but not for limiting the same, and although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that the technical solution described in the foregoing embodiments may be modified or substituted for some of the technical features thereof, and that these modifications or substitutions should not depart from the spirit and scope of the technical solution of the embodiments of the present application and should be included in the protection scope of the present application.

Claims

1. A control method of a power switching tube, comprising:

when receiving the starting signal of the power switch tube, the signal control circuit generates a starting control signal for controlling the starting of the first power switch tube and the second power switch tube according to the current feedback signal;

the power supply circuit comprises a first power switch tube, a second power switch tube, a first power switch tube, a second power switch tube and a second power switch tube, wherein the first power switch tube is an external chip sealing power tube, and the second power switch tube is an internal chip power tube;

The signal control circuit generates an opening control signal for controlling the first power switch tube and the second power switch tube according to the current feedback signal, and then comprises the following steps:

2. The method for controlling a power switch tube according to claim 1, wherein comparing, by the current control module, the current sampling voltage with a preset peak current limiting voltage and a current limiting voltage to obtain the current feedback signal comprises:

3. The control method of a power switching tube according to claim 2, wherein the method comprises:

4. The control circuit of the power switch tube for executing the control method of the power switch tube according to any one of claims 1-3, which is characterized by comprising a first power switch tube, a second power switch tube, a signal control circuit, a first driving circuit, a second driving circuit, a driving delay control circuit, a voltage control module, a sampling resistor and a current control module, wherein the first power switch tube is an external chip sealing power tube, and the second power switch tube is an internal chip power tube;

5. The power switching tube control circuit according to claim 4, wherein a first output end of the signal control circuit is connected with an input end of the first driving circuit, and an output end of the first driving circuit is connected with a first gate electrode of the first power switching tube;

6. The control circuit of the power switching tube of claim 5, wherein the driving delay control circuit comprises a first logic inverter, a second logic inverter, a third logic inverter, a NOR gate, a first resistor and a first capacitor, wherein,

The output end of the first logic inverter is connected with the second input end of the NOR gate;

The input end of the first capacitor is connected with the output end of the first resistor, and the output end of the first capacitor is grounded.

7. The power switching tube control circuit of claim 4 wherein the first power switching tube has a size that is larger than the size of the second power switching tube.

8. The power switching tube control circuit according to claim 7, wherein the first power switching tube and the second power switching tube are equal in length, and the width of the first power switching tube is an integer multiple of the width of the second power switching tube.

9. A switching power supply comprising a control circuit of a power switching tube according to any one of claims 4-8, wherein the control circuit of the power switching tube performs the control method of the power switching tube according to any one of claims 1-3.