阅读说明：本技术 开关电源主功率管驱动电路及驱动方法 (Driving circuit and driving method for main power tube of switching power supply ) 是由 不公告发明人 于 2020-07-16 设计创作，主要内容包括：本发明提出一种开关电源主功率管驱动电路及驱动方法,主功率管和采样电阻串联,根据采样电阻电压得到与采样电阻电压相关的基准电压,以驱动所述主功率管。本发明效率高,功率管不易损坏。(The invention provides a switching power supply main power tube driving circuit and a driving method. The invention has high efficiency and the power tube is not easy to damage.)

1. The utility model provides a switching power supply main power tube drive circuit, main power tube and sampling resistor are established ties which characterized in that: and obtaining a reference voltage related to the sampling resistance voltage according to the sampling resistance voltage so as to drive the main power tube.

2. The main power transistor driving circuit of claim 1, wherein: the sampling resistor and the public connecting end of the main power tube are connected with a first end of the first resistor, a second end of the first resistor is connected with a reference current source, and the voltage of the second end of the first resistor is the reference voltage.

3. The main power transistor driving circuit of claim 1, wherein: the voltage sampling circuit comprises a first voltage source, wherein the first end of the first voltage source is connected with a sampling resistor, and the output voltage of the second end of the first voltage source is the reference voltage.

4. The main power transistor driving circuit of the switching power supply as claimed in claim 2 or 3, wherein: the driving circuit further comprises a second operational amplifier and an adjusting tube, wherein a first input end of the second operational amplifier receives the reference voltage, a second input end of the second operational amplifier is connected with a second end of the adjusting tube and a control end of the main power tube, an output end of the second operational amplifier is connected with a control end of the adjusting tube, and a first end of the adjusting tube is connected with a high-potential end.

5. The utility model provides a switching power supply main power tube drive circuit, main power tube and sampling resistor are established ties which characterized in that: carrying out error amplification on the driving voltage of the main power tube and the voltage of the sampling resistor to obtain an error amplification signal; and adjusting the driving voltage of the main power tube according to the error amplification signal and the reference voltage.

6. The switching power supply main power tube driving circuit according to claim 5, wherein: the circuit comprises a first operational amplifier, a second operational amplifier and an adjusting tube, wherein the first operational amplifier carries out error amplification on a driving voltage of a main power tube and a voltage of a sampling resistor and outputs an error amplification signal; the first output end of the second operational amplifier receives the reference voltage, the second input end of the second operational amplifier receives the error amplification signal, and the output end of the second operational amplifier is connected with the control end of the adjusting tube; the first end of the adjusting tube is connected with the high potential end, and the two ends of the adjusting tube are connected with the control end of the main power tube.

7. A driving method of a main power tube of a switching power supply is characterized in that the main power tube is connected with a sampling resistor in series, and the method comprises the following steps: and obtaining a reference voltage related to the sampling resistance voltage according to the sampling resistance voltage so as to drive the main power tube.

8. A driving method of a main power tube of a switching power supply is characterized in that the main power tube is connected with a sampling resistor in series, and the method comprises the following steps: carrying out error amplification on the driving voltage of the main power tube and the voltage of the sampling resistor to obtain an error amplification signal; and adjusting the driving voltage of the main power tube according to the error amplification signal and the reference voltage.

Technical Field

The invention relates to the field of power electronics, in particular to a driving circuit and a driving method for a main power tube of a switching power supply.

Background

The main power tube of the switching power supply is often connected with a sampling resistor, and the sampling resistor is used for sampling the current of the main power tube so as to realize the relevant control of the switching power supply. The sampling resistor voltage is sampled in a positive pressure mode, the grid source voltage of the main power tube of the switching power supply is influenced by the sampling resistor voltage, and the driving voltage of the main power tube is smaller than the actual driving voltage of the main power tube. When the gate voltage of the main power tube is lower, the gate-source voltage of the main power tube is more affected, so that the driving efficiency of the main power tube becomes lower, and even the main power tube may be damaged.

Disclosure of Invention

The invention aims to provide a high-efficiency and safe driving circuit and method for a main power tube of a switching power supply, which are used for solving the problem that the driving voltage of the main power tube of the switching power supply is influenced by a sampling resistor in the prior art.

In order to achieve the purpose, the invention provides a main power tube driving circuit of a switching power supply, wherein a main power tube is connected with a sampling resistor in series, and 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.

Optionally, the sampling circuit comprises a first resistor, a common connection end of the sampling resistor and the main power tube is connected to a first end of the first resistor, a second end of the first resistor is connected to a reference current source, and a second end voltage of the first resistor is the reference voltage.

Optionally, the voltage sampling circuit comprises a first voltage source, a first end of the first voltage source is connected to the sampling resistor, and a second end of the first voltage source outputs the reference voltage.

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

The invention also provides a main power tube driving circuit of the switching power supply, wherein the main power tube is connected with the sampling resistor in series, and the driving voltage of the main power tube and the voltage of the sampling resistor are subjected to error amplification to obtain an error amplification signal; and adjusting the driving voltage of the main power tube according to the error amplification signal and the reference voltage.

Optionally, the amplifier comprises a first operational amplifier, a second operational amplifier and an adjusting tube, wherein the first operational amplifier performs error amplification on a driving voltage of the main power tube and a voltage of the sampling resistor, and outputs an error amplification signal; the first output end of the second operational amplifier receives the reference voltage, the second input end of the second operational amplifier receives the error amplification signal, and the output end of the second operational amplifier is connected with the control end of the adjusting tube; the first end of the adjusting tube is connected with the high potential end, and the two ends of the adjusting tube are connected with the control end of the main power tube.

The invention also provides a driving method of the main power tube of the switching power supply, the main power tube is connected with the sampling resistor in series, and the 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 invention also provides a driving method of the main power tube of the switching power supply, the main power tube is connected with the sampling resistor in series, and the error amplification is carried out on the driving voltage of the main power tube and the voltage of the sampling resistor to obtain an error amplification signal; adjusting the driving voltage of the main power tube according to the error amplification signal and the reference voltage

Compared with the prior art, the invention has the following advantages: the main power tube is connected with the sampling resistor in series, and 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 invention has high efficiency and the power tube is not easy to damage.

Drawings

FIG. 1 is a schematic diagram of a main power transistor driving circuit of a switching power supply according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of a second embodiment of a main power transistor driving circuit of a switching power supply according to the present invention;

FIG. 3 is a schematic diagram of a main power transistor driving circuit of a switching power supply according to an embodiment of the present invention;

Detailed Description

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, but the present invention is not limited to only these embodiments. The invention is intended to cover alternatives, modifications, equivalents and alternatives which may be included within the spirit and scope of the invention.

In the following description of the preferred embodiments of the present invention, specific details are set forth in order to provide a thorough understanding of the present invention, and it will be apparent to those skilled in the art that the present invention may be practiced without these specific details.

The invention is described in more detail in the following paragraphs by way of example with reference to the accompanying drawings. It should be noted that the drawings are in simplified form and are not to precise scale for the purpose of facilitating and clearly explaining the embodiments of the present invention.

The driving circuit receives the voltage of the sampling resistor and is used for adjusting the driving voltage of the main power tube.

As shown in fig. 1, a schematic diagram of an embodiment of a main power transistor driving circuit of a switching power supply of the present invention is illustrated, and the main power transistor driving circuit includes a first operational amplifier U01, a first regulating transistor Q1, a first current source I1, and a first resistor R1, wherein a non-inverting input terminal of the first operational amplifier U01 receives a reference voltage Vref, an inverting input terminal of the first operational amplifier U01 is connected to a control terminal of a main power transistor M1, and an output terminal of the first operational amplifier U01 is connected to a control terminal of the first regulating transistor Q1; the first end of the first adjusting transistor Q1 receives the supply voltage VCC, and the two ends thereof are connected to the control end of the main power transistor M1. One end of the first resistor R1 is connected with the main power tube, the other end is connected with the first current element I1, and the voltage of the common connection end of the first resistor R1 and the first current source I1 is the reference voltage VREF.

As shown in fig. 2, a schematic diagram of a second embodiment of the main power transistor driving circuit of the switching power supply of the invention is shown, which includes a first operational amplifier U01, a first regulating transistor Q1, and a voltage source, wherein a first end of the voltage source is connected to a common connection end of a sampling resistor Rs and a main power transistor M1, a second end of the voltage source is connected to a non-inverting input end of the first operational amplifier U01, and a second end of the voltage source is a reference voltage. The inverting input end of the first operational amplifier U01 is connected with the control end of a main power tube M1, and the output end of the first operational amplifier U01 is connected with the control end of the first adjusting tube Q1; the first end of the first adjusting transistor Q1 receives the supply voltage VCC, and the two ends thereof are connected to the control end of the main power transistor M1.

As shown in fig. 3, a schematic diagram of a main power transistor driving circuit of a switching power supply according to the embodiment of the present invention is illustrated, and the main power transistor driving circuit includes a first operational amplifier U01 and a first regulating transistor Q1, wherein a non-inverting input terminal of the first operational amplifier U01 receives a reference voltage, an inverting input terminal thereof receives an error amplified signal of the sampling signal and a main power transistor driving voltage, and an output terminal thereof is connected to a control terminal of the first regulating transistor Q1; the first end of the first adjusting tube Q1 receives the supply voltage, and the two ends thereof are connected to the control end of the main power tube. The drive circuit further comprises a second operational amplifier, the inverting input end of the first operational amplifier U01 receives the sampling signal, the non-inverting input end of the first operational amplifier U01 is connected with the control end of the main power tube, and the output end of the first operational amplifier U01 is connected with the inverting input end of the first operational amplifier U01.

The above-described embodiments do not limit the scope of the present invention. Any modification, equivalent replacement, and improvement made within the spirit and principle of the above-described embodiments should be included in the protection scope of the technical solution.