CN210724590U

CN210724590U - Power conversion circuit and electronic equipment

Info

Publication number: CN210724590U
Application number: CN201922288234.1U
Authority: CN
Inventors: 陈艳琴; 孟遥
Original assignee: Ningbo Sanxing Electric Co Ltd
Current assignee: Ningbo Sanxing Electric Co Ltd
Priority date: 2019-12-18
Filing date: 2019-12-18
Publication date: 2020-06-09
Anticipated expiration: 2029-12-18

Abstract

The application discloses a power conversion circuit and electronic equipment, wherein the power conversion circuit comprises a power input module, a first diode, a power chip and a power output module; the power input module is used for rectifying an input alternating current power supply to obtain a rectified direct current power supply; the high-voltage end of the first diode is connected with the voltage output end of the power input module; the power supply chip comprises a voltage input end and a voltage output end, the voltage input end of the power supply chip is connected with the low-voltage end of the first diode, and the voltage output end of the power supply chip is connected with the voltage input end of the power supply output module. In this embodiment, through setting up first diode at power chip's voltage input end to can block interference signal from power chip's voltage output end through power chip, avoid interference signal to cause power chip unusual.

Description

Power conversion circuit and electronic equipment

Technical Field

The application relates to the technical field of power conversion, in particular to a power conversion circuit and electronic equipment.

Background

In the step-down circuit, there are usually disturbance signals such as lightning surge signals, and it is necessary to eliminate the influence of these disturbance signals on the power management system in order to ensure the voltage stability of the output power. Generally, a voltage dependent resistor is used to clamp the input voltage to a certain voltage value, so as to eliminate the influence of interference such as lightning surge.

However, this method eliminates the influence of the interference signal such as the lightning surge from the input terminal of the power supply, and cannot effectively eliminate the influence of the interference such as the lightning surge signal on the output power supply in the circuit. For example, under the condition that the layout of a Printed Circuit Board (PCB) is not ideal, such as the PCB having an excessively long wiring or a large loop, the Circuit may generate an antenna effect or be affected by an external interference signal, such as a lightning surge signal, so that the voltage detected by the power chip may be different from the actually output voltage, thereby affecting a control loop of the power system and causing power supply abnormality.

SUMMERY OF THE UTILITY MODEL

In order to overcome at least the above-mentioned deficiencies in the prior art, an object of the present application is to provide a power conversion circuit, which includes a power input module, a first diode, a power chip and a power output module;

the power input module is used for rectifying an input alternating current power supply to obtain a rectified direct current power supply;

the high-voltage end of the first diode is connected with the voltage output end of the power input module;

the power supply chip comprises a voltage input end and a voltage output end, the voltage input end of the power supply chip is connected with the low-voltage end of the first diode, and the voltage output end of the power supply chip is connected with the voltage input end of the power supply output module.

Optionally, the power input module includes a voltage clamping unit, a filtering unit, a rectifying unit and a smoothing unit;

two ends of the voltage clamping unit are respectively connected with a first alternating current input end and a second alternating current input end of the power input module, so that the voltage between the first alternating current input end and the second alternating current input end is maintained within a preset voltage range;

the filtering unit is connected between the first alternating current input end and the second alternating current input end;

the rectifying unit is connected with the output end of the filtering unit and is used for rectifying the voltage output by the filtering unit;

the smoothing unit is connected between the output end of the rectifying unit and the second alternating current input end and used for inhibiting the fluctuation of the voltage output by the rectifying unit.

Optionally, the voltage clamping unit comprises a varistor connected between the first ac input and the second ac input.

Optionally, the filtering unit includes a first inductor, a first resistor, and a first capacitor, one end of the first inductor is connected to the first ac input terminal, the other end of the first inductor is connected to the first end of the first resistor, and the first capacitor is connected between the second end of the first resistor and the second ac input terminal.

Optionally, the rectifying unit includes a second diode and a third diode, a high voltage end of the second diode is connected to the second end of the first resistor, and a low voltage end of the second diode is connected to a high voltage end of the third diode.

Optionally, the smoothing unit includes a first electrolytic capacitor and a second electrolytic capacitor connected in series, an anode of the first electrolytic capacitor is connected to the low-voltage end of the third diode, a cathode of the first electrolytic capacitor is connected to an anode of the second electrolytic capacitor, and a cathode of the second electrolytic capacitor is connected to the second ac input terminal;

the first electrolytic capacitor and the second electrolytic capacitor are respectively connected with a divider resistor in parallel.

Optionally, the power output module includes a first dc output unit and a second dc output unit;

the voltage input end of the first direct current output unit is connected with the voltage output end of the power supply chip, and the voltage output end of the first direct current output unit is connected with the second direct current output unit.

Optionally, the first dc output unit includes a second resistor, a third resistor, and a second capacitor connected in parallel;

one end of the second resistor, which is far away from the power supply chip, is connected with a first end of a second inductor, and a second end of the second inductor is grounded through a third capacitor and a third electrolytic capacitor respectively;

and one end of the second resistor, which is far away from the power supply chip, is also respectively connected with a low-voltage end of a fourth diode and a low-voltage end of a fifth diode and is grounded through the fourth diode and the fifth diode, wherein a second end of the second inductor forms a voltage output end of the first direct current output unit.

Optionally, the second dc output unit includes a sixth diode, a high-voltage end of the sixth diode is connected to the voltage output end of the first dc output unit, a low-voltage end of the sixth diode is connected to a fourth resistor, and the fourth resistor is grounded through a fourth capacitor and a fourth electrolytic capacitor, respectively;

the second direct current output unit further comprises a seventh diode connected with the voltage output end of the first direct current output unit through a high voltage end, and the low voltage end of the seventh diode forms the voltage output end of the second direct current output unit.

Another object of the present application is to provide an electronic device, which includes a circuit board and the power conversion circuit according to any of the present application, wherein a voltage output end of the power conversion circuit is connected to a power supply port of the circuit board.

Compared with the prior art, the method has the following beneficial effects:

the embodiment of the application provides a power supply conversion circuit and electronic equipment, through connect a first diode between the voltage input end at power chip and the voltage output end of power input module, thus, with first diode lug connection on power chip's voltage input end, when there is interference signal such as thunderbolt surge signal in the structure of connecting on power chip's the voltage output end, because the existence of first diode, can block the route of interference signal transmission, make the voltage that power chip gathered be exactly its actual output's voltage, power chip is carrying out power management during operation, can control the management according to its actual output's voltage, interference signal's influence has been avoided.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are required to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained from the drawings without inventive effort.

Fig. 1 is a schematic block diagram of a structure of a power conversion circuit provided in an embodiment of the present application;

fig. 2 is a block diagram schematically illustrating a structure of a power conversion circuit according to an embodiment of the present disclosure;

fig. 3 is a circuit configuration diagram of a power conversion circuit according to an embodiment of the present application;

fig. 4 is a circuit structure diagram of a power conversion circuit according to an embodiment of the present application.

Icon: 100-a power input module; 110-a power supply chip; 120-a power output module; 101-a voltage clamping unit; 102-a filtering unit; 103-a rectifying unit; 104-a smoothing unit; 121-a first dc output unit; 122-second dc output unit.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some embodiments of the present application, but not all embodiments. The components of the embodiments of the present application, generally described and illustrated in the figures herein, can be arranged and designed in a wide variety of different configurations.

Thus, the following detailed description of the embodiments of the present application, presented in the accompanying drawings, is not intended to limit the scope of the claimed application, but is merely representative of selected embodiments of the application. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.

In the description of the present application, it is further noted that, unless expressly stated or limited otherwise, the terms "disposed," "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present application can be understood in a specific case by those of ordinary skill in the art.

Many devices employ power management systems to convert power, such as converting high voltage ac power to low voltage dc power, to achieve a desired power voltage. During the power conversion process, the power chip 110 in the power management system usually adjusts its operating state according to the output voltage, such as increasing the output, decreasing the output, and so on.

For the power management system, some interference exists inevitably in the working process, and in order to reduce the abnormal influence of the interference signals on the power supply, in one embodiment, a clamping module is arranged at the power supply input end of the power management system, and the voltage input by the power supply input end is limited within a specific voltage range through the clamping module, so that the power supply abnormality caused by the interference signals such as lightning surge signals is reduced.

In the power conversion circuit, when the PCB is too long and the loop is large, the PCB may generate an antenna effect to receive an external interference signal, such as a common lightning strike signal, the interference signal at the power output end may be transmitted to the input end of the power chip 110 from the power output end of the power chip 110, so that the voltage at the output end detected by the power chip 110 is inconsistent with the actually output voltage thereof, thereby causing power abnormality.

In order to solve the problem that the interference signal causes the abnormality of the power supply (output voltage) of the power supply conversion circuit, the application provides a power supply conversion scheme.

Referring to fig. 1, fig. 1 is a schematic block diagram of a first structure of a power conversion circuit provided in an embodiment of the present application, where the power conversion circuit includes a power input module 100, a first diode D1, a power chip 110, and a power output module 120.

The power input module 100 is configured to rectify an input ac power to obtain a rectified dc power; the high-voltage end of the first diode D1 is connected with the voltage output end of the power input module 100;

the power supply chip 110, i.e., a power management chip, is a chip that plays roles of conversion, distribution, detection, and other power management of power in an electronic device system, and is used for controlling whether or not an input voltage is output. The power chip 110 includes a voltage input terminal and a voltage output terminal, the voltage input terminal of the power chip 110 is connected to the low voltage terminal of the first diode D1, and the voltage output terminal of the power chip 110 is connected to the voltage input terminal of the power output module 120.

When the voltage input terminal of the power chip 110 and the voltage output terminal of the power chip 110 are connected, a path may be formed therebetween, and at this time, an interference signal generated in a circuit connected to the output terminal of the power chip 110 may be transmitted through the path between the voltage input terminal of the power chip 110 and the voltage output terminal of the power chip 110, so that the power chip 110 detects that a large deviation exists between an actually output voltage and an actual voltage, and the power chip 110 performs a power management operation according to the voltage having the deviation.

In this embodiment, a first diode D1 is connected between the voltage input terminal of the power chip 110 and the voltage output terminal of the power input module 100, so that the first diode D1 is directly connected to the voltage input terminal of the power chip 110, when there is an interference signal such as a lightning surge signal in the structure connected to the voltage output terminal of the power chip 110, due to the existence of the first diode D1, the path of transmission of the interference signal can be blocked, so that the voltage collected by the power chip 110 is the voltage output by the power chip, when the power chip 110 performs power management work, control management is performed according to the voltage actually output by the power chip, and the influence of the interference signal is avoided.

In this embodiment, the diode D1 may be a fast recovery diode USIM.

Referring to fig. 2, optionally, in the present embodiment, the power input module 100 includes a voltage clamping unit 101, a filtering unit 102, a rectifying unit 103, and a smoothing unit 104. Two ends of the voltage clamping unit 101 are respectively connected to the first ac input end UN and the second ac input end GND of the power input module 100, so that the voltage between the first ac input end and the second ac input end is maintained within a preset voltage range. The first alternating current input end is a zero line, and the second alternating current input end is a live line.

The filtering unit 102 is connected between the first ac input terminal and the second ac input terminal.

The rectifying unit 103 is connected to an output end of the filtering unit 102, and is configured to rectify the voltage output by the filtering unit 102.

The smoothing unit 104 is connected between the output end of the rectifying unit 103 and the second ac input end, and is configured to suppress fluctuation of the voltage output by the rectifying unit 103.

In this embodiment, the voltage clamping unit 101 is connected between the first ac input terminal and the second ac input terminal, so that the voltage of the input ac can be maintained within a certain range, and thus, the influence of the lightning strike signal in the power input module 100 on the voltage finally output by the power conversion circuit can be avoided. The filtering unit 102 is disposed between the first ac input terminal and the second ac input terminal, so as to filter out interference signals in the input ac power. The rectifying unit 103 can rectify the power supply after the interference is filtered by the filtering unit 102 to obtain a dc power supply, and the smoothing unit 104 further processes the dc power supply, so that the dc power supply is more stable.

Referring to fig. 3, optionally, in this embodiment, the voltage clamping unit 101 includes a voltage dependent resistor RV, and the voltage dependent resistor RV is connected between the first ac input terminal and the second ac input terminal.

The varistor RV is a voltage-limiting element sensitive to voltage variations, and has the characteristics that at a given temperature, when the voltage exceeds a certain critical value, the resistance thereof is sharply reduced, the current passing through it is sharply increased, and the voltage and the current do not have a linear relationship. In this embodiment, the varistor RV has a simple structure.

Referring to fig. 3, optionally, in the embodiment, the filtering unit 102 includes a first inductor L1, a first resistor R1, and a first capacitor C1, one end of the first inductor L1 is connected to the first ac input terminal, the other end of the first inductor L1 is connected to a first end of a first resistor R1, and the first capacitor C1 is connected between a second end of the first resistor R1 and the second ac input terminal.

In this embodiment, the first inductor L1, the first resistor R1, and the first capacitor C1 in the filtering unit 102 can cooperate with each other to further filter the interference signal in the ac power input by the power input module 100.

Specifically, the first resistor R1 may be a ground resistor having a resistance of 33 ohms and a power of 3 watts. The first capacitor C1 may be a capacitor with a capacitance of 0.1 muf and a rated voltage of 315V.

Referring to fig. 3, optionally, in the present embodiment, the rectifying unit 103 includes a second diode D2 and a third diode D3, a high voltage end of the second diode D2 is connected to the second end of the first resistor R1, and a low voltage end of the second diode D2 is connected to a high voltage end of the third diode D3.

In this embodiment, the second diode D2 and the third diode D3 are connected in series as the rectifying unit 103, and the withstand voltage range of the rectifying unit 103 can be increased.

The second diode D2 and the third diode D3 may both be diodes of type EM 520.

With reference to fig. 3, optionally, in this embodiment, the smoothing unit 104 includes a first electrolytic capacitor CE1 and a second electrolytic capacitor CE2 connected in series, an anode of the first electrolytic capacitor CE1 is connected to the low voltage end of the third diode D3, a cathode of the first electrolytic capacitor CE1 is connected to an anode of the second electrolytic capacitor CE2, and a cathode of the second electrolytic capacitor CE2 is connected to the second ac input end; the first electrolytic capacitor CE1 and the second electrolytic capacitor CE2 are connected in parallel to a voltage dividing resistor, respectively.

In this embodiment, the electrolytic capacitor is used as a smoothing capacitor, and has a good smoothing effect. In the present embodiment, a voltage dividing resistor is connected in parallel to each of the first electrolytic capacitor CE1 and the second electrolytic capacitor CE2, so that a stable voltage difference is generated between both ends of each of the first electrolytic capacitor CE1 and the second electrolytic capacitor CE 2. Thereby enabling to improve the smoothing effect. Each divider resistor may be a chip resistor. And the volume of the whole circuit can be reduced by adopting the chip resistor.

In this embodiment, when the voltage dividing resistor is a chip resistor, a plurality of chip resistors may be connected in series to form the voltage dividing resistor. For example, the voltage dividing resistor connected in parallel with the first electrolytic capacitor CE1 may be formed by connecting a first chip resistor RT1, a second chip resistor RT2, and a third chip resistor RT3 in series, and the voltage dividing resistor connected in parallel with the second electrolytic capacitor CE2 may be formed by connecting a fourth chip resistor RT4, a fifth chip resistor RT5, and a sixth chip resistor RT6 in series.

In this embodiment, adopt a plurality of chip resistor to establish ties and constitute divider resistor, when reducing the circuit volume, can also improve divider resistor's withstand voltage value to can improve chip resistor's live time.

In this embodiment, the first electrolytic capacitor CE1 may have a capacitance of 0.1nF and a rated voltage of 400KV, and the second electrolytic capacitor CE2 may have a capacitance of 0.1nF and a rated voltage of 400 KV. The first chip resistor RT1, the second chip resistor RT2, the third chip resistor RT3, the fourth chip resistor RT4, the fifth chip resistor RT5 and the sixth chip resistor RT6 may all adopt resistors with resistance of 1 megaohm and accuracy of 1%, for example, a resistor of type 0805.

Referring to fig. 3, optionally, in the present embodiment, the power output module 120 includes a first dc output unit 121, a voltage input terminal of the first dc output unit 121 is connected to a voltage output terminal of the power chip 110, and the first dc output unit 121 includes a second resistor R2, a third resistor R3, and a second capacitor C2 connected in parallel.

One end of the second resistor R1, which is far away from the power chip 110, is grounded, one end of the second resistor R1, which is far away from the power chip 110, is connected to the first end of a second inductor L2, and the second end of the second inductor L2 is grounded through a third capacitor C3 and a third electrolytic capacitor CE3, respectively.

One end of the second resistor R2, which is far away from the power chip 110, is further connected to a low voltage end of the fourth diode D4 and a low voltage end of the fifth diode D5, and is grounded through the fourth diode D4 and the fifth diode D5, wherein the second end of the second inductor L2 constitutes a voltage output end of the first dc output unit 121.

In this embodiment, the second resistor R2 and the third resistor R3 are used as voltage sampling resistors, and the second capacitor C2 is connected in parallel to the second resistor and the third resistor, so as to perform high-frequency filtering on the power output by the power chip 110. The second inductor L2 and the third electrolytic capacitor CE3 are used for filtering the current passing through the second resistor and the third resistor, so that the output direct-current power supply can be more stable. The third capacitor C3 can stabilize the output dc power.

The fourth diode D4 and the fifth diode D5 may both be diodes of the USIM type. The second resistor R2 may be a resistor with a resistance of 2 ohms and an accuracy of 1%, and the third resistor R3 may be a resistor with a resistance of 2 ohms and an accuracy of 1%, for example, a resistor model 1206. The second capacitor C2 may be a capacitor with a capacitance of 33pF and a nominal voltage of 50V, the third capacitor C3 may be a capacitor with a capacitance of 0603, and the third electrolytic capacitor CE3 may be a capacitor with a capacitance of 1000 μ F and a nominal voltage of 25V.

Referring to fig. 4, optionally, in this embodiment, the power output module 120 may further include a second dc output unit 122. The voltage output terminal of the first dc output unit 121 is connected to the second dc output unit 122.

In this embodiment, the power output module 120 is divided into two dc output units, which can output two dc power sources, so as to provide dc power for different devices.

Referring to fig. 4, optionally, in this embodiment, the second dc output unit 122 includes a sixth diode D6, a high voltage end of the sixth diode D6 is connected to the voltage output end of the first dc output unit 121, a low voltage end of the sixth diode D6 is connected to a fourth resistor R4, and the fourth resistor R4 is grounded through a fourth capacitor C4 and a fourth electrolytic capacitor CE4, respectively.

The second dc output unit 122 further includes a seventh diode D7 connected to the voltage output terminal of the first dc output unit 121 through a high voltage terminal, and a low voltage terminal of the seventh diode D7 constitutes the voltage output terminal of the second dc output unit.

In this embodiment, the fourth resistor R4 and the fourth capacitor C4 are connected to a power supply VCC _ HF 920.

In this embodiment, the sixth diode D6 and the seventh diode D7 are arranged to enable the voltage output end of the first dc output unit 121 and the voltage output end of the second dc output unit 122 to be relatively independent, so as to prevent the electric device connected to the output end of the second dc output unit 122 from affecting the voltage output by the output end of the first dc output unit 121. Both the sixth diode D6 and the seventh diode D7 may be diodes of type IN 4007. The fourth resistor R2 may be a resistor with a resistance of 2 ohms and an accuracy of 1%, for example, a resistor model 1206. The fourth capacitor C4 may be a capacitor with a capacitance of 0.1 muf and a nominal voltage of 50V, for example a 0603 capacitor. The fourth electrolytic capacitor CE4 can be an electrolytic capacitor with a rated voltage of 50V and 22 uF.

In this embodiment, the power chip 110 is further connected to a peripheral circuit. For example, when the power chip 110 has the model number of HF920, the voltage input terminal of the power chip 110 is the drain D of the fet built in the power chip 110, and the voltage output terminal of the power chip 110 is the source S of the fet built in the power chip 110. The free end NC of the power supply chip 110 is not connected to the device. The first ground GND1 and the second ground GND2 of the power chip 110 are grounded PGND. The power supply terminal VCC of the power supply chip 110 is connected with the power supply VCC _ HF920, the switching frequency setting terminal FSET of the power supply chip 110 is grounded through a fifth resistor R5 and a fifth capacitor C5 which are connected in parallel, the overvoltage protection terminal PRO of the power supply chip 110 and the third ground terminal GND3 of the power supply chip 110 are grounded through a fourth ground terminal GND4 of the power supply chip 110, the FB of the power supply chip 110 is grounded through a sixth capacitor C6, the feedback terminal FB of the power supply chip 110 is also connected with the collector of the triode V, the emitter of the triode V is grounded through a sixth resistor R6, the base of the sixth resistor R6 is connected with the high-voltage terminal of the zener diode D8, the high-voltage terminal of the zener diode D8 is grounded through an eighth resistor R8, and the low-voltage terminal of the zener diode D8 is connected with the power supply VCC _ HF 920.

In the above example, the fifth resistor R5 may be a resistor having a resistance of 330 kohm with an accuracy of 1%, for example, a resistor of type 0602; the fifth capacitor C5 may be a capacitor with a capacitance value of 1nF and a rated voltage of 50V, such as a type 0402 capacitor; the sixth capacitor C6 may be a capacitor with a capacitance value of 1nF and a rated voltage of 50V, such as a type 0402 capacitor; the sixth resistor R6 may be a resistor with a resistance of 100 ohms and a precision of 1%, for example a type 0402 resistor; the seventh resistor R7 may be a resistor with a resistance of 1 kilo-ohm and a precision of 1%, for example, a type 0402 resistor; the eighth resistor R8 may be a resistor with a resistance of 1 kilo-ohm and a precision of 1%, for example, a type 0402 resistor; the Zener diode can adopt a Zener diode with the model number SMA4744A and the rated voltage of 15V.

The present embodiment further provides an electronic device, where the electronic device includes a circuit board and the power conversion circuit according to any one of the embodiments, and a voltage output end of the power conversion circuit is connected to a power supply port of the circuit board.

The electronic device of this embodiment adopts the power conversion circuit described above in this embodiment, so that a stable power supply can be obtained, and thus the electronic device can operate more stably.

The above description is only for various embodiments of the present application, but the scope of the present application is not limited thereto, and any person skilled in the art can easily conceive of changes or substitutions within the technical scope of the present application, and all such changes or substitutions are included in the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A power conversion circuit is characterized by comprising a power input module, a first diode, a power chip and a power output module;

2. The circuit of claim 1, wherein the power input module comprises a voltage clamping unit, a filtering unit, a rectifying unit and a smoothing unit;

3. The circuit of claim 2, wherein the voltage clamping unit comprises a varistor connected between the first ac input and the second ac input.

4. The circuit of claim 3, wherein the filtering unit comprises a first inductor, a first resistor, and a first capacitor, one end of the first inductor is connected to the first ac input terminal, the other end of the first inductor is connected to a first end of the first resistor, and the first capacitor is connected between a second end of the first resistor and the second ac input terminal.

5. The circuit of claim 4, wherein the rectifying unit comprises a second diode and a third diode, a high voltage terminal of the second diode is connected to the second terminal of the first resistor, and a low voltage terminal of the second diode is connected to a high voltage terminal of the third diode.

6. The circuit of claim 5, wherein the smoothing unit comprises a first electrolytic capacitor and a second electrolytic capacitor connected in series, an anode of the first electrolytic capacitor is connected to the low voltage end of the third diode, a cathode of the first electrolytic capacitor is connected to an anode of the second electrolytic capacitor, and a cathode of the second electrolytic capacitor is connected to the second alternating current input end;

7. The circuit of claim 1, wherein the power output module comprises a first dc output unit and a second dc output unit;

8. The circuit of claim 7, wherein the first DC output unit comprises a second resistor, a third resistor and a second capacitor connected in parallel;

9. The circuit of claim 7, wherein the second dc output unit comprises a sixth diode, a high voltage end of the sixth diode is connected to the voltage output end of the first dc output unit, a low voltage end of the sixth diode is connected to a fourth resistor, and the fourth resistor is grounded through a fourth capacitor and a fourth electrolytic capacitor, respectively;

10. An electronic device, characterized in that the electronic device comprises a circuit board and the power conversion circuit according to any one of claims 1-9, wherein a voltage output terminal of the power conversion circuit is connected with a power supply port of the circuit board.