Switching power supply main power tube driving circuit and driving method

Abstract

The application provides a switching power supply main power tube driving circuit and a driving method. A main power tube and a sampling resistor are connected in series. A reference voltage related to the voltage of the sampling resistor is obtained according to the voltage of the sampling resistor, so as to drive the main power tube. The application has high efficiency and the power tube is not easy to be damaged.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of power electronics, in particular to a switching power supply main power tube driving circuit and driving method. BACKGROUND

[0002] The switching power supply main power tube is often connected with a sampling resistor, which is used to sample the main power tube current to realize the related control of the switching power supply. The sampling resistor voltage is obtained by positive voltage sampling, and the gate-source voltage of the switching power supply main power tube will be affected by the sampling resistor voltage, causing the driving voltage of the main power tube to be smaller than its actual driving voltage. When the gate voltage of the main power tube is low, the gate-source voltage will be more affected, causing the driving efficiency of the main power tube to be low, and even the main power tube may be damaged. SUMMARY

[0003] The purpose of the present application is to provide a high-efficiency and safe switching power supply main power tube driving circuit and driving method to solve the problem of the driving voltage of the switching power supply main power tube being affected by the sampling resistor in the prior art.

[0004] To achieve the above-mentioned purpose, the present application provides a switching power supply main power tube driving circuit, the main power tube and the sampling resistor are connected in series, and a reference voltage related to the sampling resistor voltage is obtained according to the sampling resistor voltage to drive the main power tube.

[0005] Optionally, a first resistor is included, the common connection end of the sampling resistor and the main power tube is connected to the first end of the first resistor, the second end of the first resistor is connected to a reference current source, and the voltage at the second end of the first resistor is the reference voltage.

[0006] Optionally, a first voltage source is included, the first end of the first voltage source is connected to the sampling resistor, and the output voltage at the second end of the first voltage source is the reference voltage.

[0007] Optionally, the driving circuit further includes a second operational amplifier and an adjusting tube, the first input end of the second operational amplifier receives the reference voltage, the second input end of the second operational amplifier is connected to the second end of the adjusting tube and the control end of the main power tube, the output end of the second operational amplifier is connected to the control end of the adjusting tube, and the first end of the adjusting tube is connected to a high potential end.

[0008] The present application also provides a switching power supply main power tube driving circuit, the main power tube and the sampling resistor are connected in series, the driving voltage of the main power tube and the sampling resistor voltage are error amplified to obtain an error amplified signal, and the driving voltage of the main power tube is adjusted according to the error amplified signal and a reference voltage.

[0009] Optionally, the first operational amplifier, the second operational amplifier and the adjusting tube are included, the first operational amplifier amplifies the error between the main power tube driving voltage and the sampling resistance voltage and outputs the error amplification signal; the second operational amplifier receives the reference voltage at the first output end, receives the error amplification signal at the second input end and connects the output end to the control end of the adjusting tube; and the first end of the adjusting tube is connected to the high potential end and the second end is connected to the control end of the main power tube.

[0010] The application also provides a main power tube driving method of a switching power supply, the main power tube and the sampling resistance are connected in series, the reference voltage related to the sampling resistance voltage is obtained according to the sampling resistance voltage to drive the main power tube.

[0011] The application also provides a main power tube driving method of a switching power supply, the main power tube and the sampling resistance are connected in series, the reference voltage related to the sampling resistance voltage is obtained according to the sampling resistance voltage to drive the main power tube.

[0012] Compared with the prior art, the application has the following advantages: the main power tube and the sampling resistance are connected in series, the reference voltage related to the sampling resistance voltage is obtained according to the sampling resistance voltage to drive the main power tube. The application has high efficiency and the power tube is not easy to be damaged. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 Figure 1 is a schematic diagram of the first embodiment of the main power tube driving circuit of the switching power supply of the application;

[0014] Figure 2 Figure 2 is a schematic diagram of the second embodiment of the main power tube driving circuit of the switching power supply of the application;

[0015] Figure 3 Figure 3 is a schematic diagram of the third embodiment of the main power tube driving circuit of the switching power supply of the application; DETAILED DESCRIPTION

[0016] The preferred embodiments of the application are described in detail below with reference to the accompanying drawings, but the application is not limited to these embodiments. The application covers any alternatives, modifications, equivalent methods and schemes within the spirit and scope of the application.

[0017] In order for the public to have a thorough understanding of the application, the specific details are described in the following preferred embodiments of the application, and the application can also be completely understood without the description of these details by those skilled in the art.

[0018] The application is described in more detail with examples and with reference to the accompanying drawings in the following paragraphs. It should be noted that the drawings are in a simplified form and use non-precise proportions to facilitate and clarify the purpose of illustrating the embodiments of the application.

[0019] The main power tube and the sampling resistor are connected in series, one end of the sampling resistor is connected to the main power tube, and the other end is grounded. The driving circuit of the application receives the voltage of the sampling resistor to adjust the driving voltage of the main power tube.

[0020] As shown in Figure 1 Figure 1 is a schematic diagram of the main power tube driving circuit of the switching power supply according to the first embodiment of the application, which comprises a first operational amplifier U01, a first adjusting tube Q1, a first current source I1 and a first resistor R1. The non-inverting input terminal of the first operational amplifier U01 receives a reference voltage Vref, the inverting input terminal is connected to the control terminal of the main power tube M1, and the output terminal is connected to the control terminal of the first adjusting tube Q1. The first end of the first adjusting tube Q1 receives a supply voltage VCC, and the second end is connected to the control terminal of the main power tube M1. One end of the first resistor R1 is connected to the main power tube, and the other end is connected to the first current source I1. The common connection terminal voltage of the first resistor R1 and the first current source I1 is the reference voltage VREF.

[0021] As shown in Figure 2 Figure 2 is a schematic diagram of the main power tube driving circuit of the switching power supply according to the second embodiment of the application, which comprises a first operational amplifier U01, a first adjusting tube Q1 and a voltage source. The first end of the voltage source is connected to the common connection terminal of the sampling resistor Rs and the main power tube M1, and the second end is connected to the non-inverting input terminal of the first operational amplifier U01. The voltage of the second end of the voltage source is the reference voltage. The inverting input terminal of the first operational amplifier U01 is connected to the control terminal of the main power tube M1, and the output terminal is connected to the control terminal of the first adjusting tube Q1. The first end of the first adjusting tube Q1 receives a supply voltage VCC, and the second end is connected to the control terminal of the main power tube M1.

[0022] As shown in Figure 3 Figure 3 is a schematic diagram of the main power tube driving circuit of the switching power supply according to the third embodiment of the application, which comprises a first operational amplifier U01 and a first adjusting tube Q1. The non-inverting input terminal of the first operational amplifier U01 receives a reference voltage, the inverting input terminal receives an error amplification signal of the sampling signal and the main power tube driving voltage, and the output terminal is connected to the control terminal of the first adjusting tube Q1. The first end of the first adjusting tube Q1 receives a supply voltage, and the second end is connected to the control terminal of the main power tube. The driving circuit further comprises a second operational amplifier. The inverting input terminal of the first operational amplifier U01 receives the sampling signal, the non-inverting input terminal is connected to the control terminal of the main power tube, and the output terminal is connected to the inverting input terminal of the first operational amplifier U01.

[0023] The above-described embodiments do not constitute a limitation on the scope of protection of the technical solution. Any modifications, equivalent replacements and improvements made within the spirit and principles of the above-described embodiments shall be included in the scope of protection of the technical solution.

Claims

1. A main power transistor drive circuit for a switching power supply, wherein the main power transistor and a sampling resistor are connected in series, characterized in that: A reference voltage related to the sampling resistor voltage is obtained according to the sampling resistor voltage to drive the main power tube, and the reference voltage is equal to the sum of the sampling resistor voltage and a preset voltage; The driving circuit further comprises a first operational amplifier and an adjusting tube, the first input end of the first operational amplifier receives the reference voltage, the second input end of the first operational amplifier is connected to the second end of the adjusting tube and the control end of the main power tube, the output end of the first operational amplifier is connected to the control end of the adjusting tube, and the first end of the adjusting tube is connected to the high potential end.

2. The switching power supply main power tube drive circuit according to claim 1, characterized in that: The first end of the first resistor is connected to the common connection end of the sampling resistor and the main power tube, the second end of the first resistor is connected to a reference current source, the voltage at the second end of the first resistor is the reference voltage, and the voltage of the first resistor is the preset voltage.

3. The switching power supply main power tube drive circuit according to claim 1, characterized in that: The first end of the first voltage source is connected to the sampling resistor, and the voltage output at the second end of the first voltage source is the reference voltage, and the voltage of the first voltage source is the preset voltage.

4. A switching power supply main power tube driving circuit, the main power tube and a sampling resistor are connected in series, characterized in that: The main power tube driving voltage and the sampling resistor voltage are error-amplified to obtain an error-amplified signal, and the driving voltage of the main power tube is adjusted according to the error-amplified signal and the reference voltage. The second operational amplifier receives the reference voltage at the first output end, receives the error-amplified signal at the second input end, and connects the control end of the adjusting tube at the output end; the first end of the adjusting tube is connected to the high potential end, and the second end is connected to the control end of the main power tube.

5. The switching power supply main power tube drive circuit according to claim 4, characterized in that: The first operational amplifier error-amplifies the main power tube driving voltage and the sampling resistor voltage to output an error-amplified signal.

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