CN213906292U

CN213906292U - Protection circuit of flyback power supply

Info

Publication number: CN213906292U
Application number: CN202022988182.1U
Authority: CN
Inventors: 王西前; 毛存; 尚庆荣; 桂春汛
Original assignee: Shanghai Fengtian Electronics Co ltd
Current assignee: Shanghai Fengtian Electronics Co ltd
Priority date: 2020-12-11
Filing date: 2020-12-11
Publication date: 2021-08-06
Anticipated expiration: 2030-12-11

Abstract

The utility model relates to the technical field of protection circuit, specifically disclose a protection circuit of flyback power supply, including input filter protection circuit, input sampling circuit, flyback control chip power enable control circuit, flyback power conversion absorption circuit, transformer, input filter protection circuit, flyback control chip power enable control circuit interconnect, flyback control chip power enable control circuit is connected with flyback power conversion control circuit; the protection circuit, the input sampling circuit, the flyback power conversion absorption circuit and the flyback power conversion control circuit are connected with the input end of the transformer; the output end of the transformer is connected with a flyback first output circuit and a flyback second output circuit; the utility model discloses the circuit can effectively protect the former vice limit of flyback power supply, can also realize self-locking function, and circuit protection has prevented the ripples of trouble effectively and has enlarged for flyback power supply's reliability obtains improving.

Description

Protection circuit of flyback power supply

Technical Field

The utility model relates to a protection circuit technical field specifically is a flyback power's protection circuit.

Background

With the rapid development of power electronic technology, the rapid development and improvement of the switching power supply are promoted, the application field is more and more extensive, and the proportion occupied by the switching power supply in the whole power supply field is larger and larger.

A flyback circuit is adopted as a low-power supply, and is generally dozens of watts, and more than one hundred watts at a high point. The most common are cell phone chargers, vehicle mounted inverters, electric vehicle chargers, electric vehicle voltage inverters, notebook power adapters, power supplies in desktop computer cases, UPS power supplies, chargers for MP3 and MP4, and the like. But also in household DVD and LCD TV. The wide application of the flyback power supply makes higher requirements, such as high efficiency, good performance, small volume, light weight and the like, necessary for safety and reliability.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to provide a flyback power supply's protection circuit to solve the problem that proposes in the above-mentioned background art.

In order to achieve the above object, the utility model provides a following technical scheme: a protection circuit of a flyback power supply comprises an input filter protection circuit, a protection circuit, an input sampling circuit, a flyback control chip power supply enabling control circuit, a flyback power supply conversion absorption circuit and a transformer, wherein the input filter protection circuit, the protection circuit and the flyback control chip power supply enabling control circuit are connected with each other, and the flyback control chip power supply enabling control circuit is connected with the flyback power supply conversion control circuit; the protection circuit, the input sampling circuit, the flyback power conversion absorption circuit and the flyback power conversion control circuit are connected with the input end of the transformer; the output end of the transformer is connected with a flyback first output circuit and a flyback second output circuit.

Preferably, the input end of the transformer is provided with a pin 1 and a pin 2, wherein the protection circuit, the input sampling circuit and the flyback power conversion absorption circuit are connected with the pin 1, and the flyback power conversion absorption circuit and the flyback power conversion control circuit are connected with the pin 2.

Preferably, a filter supporting capacitor C4 is connected between the protection circuit and the flyback power conversion absorption circuit.

Preferably, the output end of the transformer is provided with a pin 9 and a pin 10, the first flyback output circuit is connected with the pin 9 and the pin 10, and the first flyback output circuit is connected with the first flyback bypass output circuit.

Preferably, the output end of the transformer is provided with 6 pins and 7 pins, the flyback second output circuit is connected with the 6 pins and the 7 pins, and the flyback second output circuit is connected with the flyback second output sampling circuit 1 and the flyback power supply conversion control circuit.

Compared with the prior art, the beneficial effects of the utility model are that: the utility model discloses the circuit can effectively protect the former vice limit of flyback power supply, specifically include short-circuit protection, overvoltage protection, undervoltage protection, overcurrent protection, can also realize self-locking function, and circuit protection has prevented the fluctuation of trouble effectively and has enlarged for flyback power supply's reliability obtains improving.

Drawings

Fig. 1 is a schematic structural view of the present invention;

reference numbers in the figures: 1. an input filter protection circuit; 2. a protection circuit; 3. an input sampling circuit; 4. a power supply enabling control circuit of the flyback control chip; 5. a flyback power conversion absorption circuit; 6. a flyback power conversion control circuit; 7. a transformer; 8. flyback to the first output circuit; 9. flyback to a first bypass output circuit; 10. flyback the second output circuit; 11. and flyback the second output sampling circuit.

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.

Referring to fig. 1, the present invention provides a technical solution: a protection circuit of a flyback power supply comprises an input filter protection circuit 1, a protection circuit 2, an input sampling circuit 3, a flyback control chip power supply enabling control circuit 4, a flyback power supply conversion absorption circuit 5 and a transformer 7, wherein the input filter protection circuit 1, the protection circuit 2 and the flyback control chip power supply enabling control circuit 4 are connected with each other, and the flyback control chip power supply enabling control circuit 4 is connected with a flyback power supply conversion control circuit 6; the protection circuit 2, the input sampling circuit 3, the flyback power conversion absorption circuit 5 and the flyback power conversion control circuit 6 are connected with the input end of the transformer 7; the output end of the transformer 7 is connected with a flyback first output circuit 8 and a flyback second output circuit 10.

Furthermore, the input end of the transformer 7 is provided with pins 1 and 2, wherein the protection circuit 2, the input sampling circuit 3, the flyback power conversion absorption circuit 5 and the pins 1 are connected, and the flyback power conversion absorption circuit 5, the flyback power conversion control circuit 6 and the pins 2 are connected.

Furthermore, a filter supporting capacitor C4 is connected between the protection circuit 2 and the flyback power conversion absorption circuit 5.

Furthermore, the output end of the transformer 7 is provided with a pin 9 and a pin 10, the flyback first output circuit 8 is connected with the pin 9 and the pin 10, and the flyback first output circuit is connected with the flyback first bypass output circuit 9.

Furthermore, the output end of the transformer 7 is provided with a pin 6 and a pin 7, the flyback second output circuit 10 is connected with the pin 6 and the pin 7, and the flyback second output circuit 10 is connected with the flyback second output sampling circuit 11 and the flyback power supply conversion control circuit 6.

The working principle is as follows: after being powered on, the input filter protection circuit 1 firstly charges a capacitor C4 through R1 in the protection circuit 2, when no short circuit of the rear end circuit is detected, the input sampling circuit 3 detects a normal voltage value, the controller MCU gives out a control signal MCU _ KL30_ SW _ CTRL high level to ensure that the protection circuit 2 is normally switched on and the rear end voltage of the protection circuit 2 is normally supplied, meanwhile, the controller MCU gives a low-level enable signal to the MCU _ KL30_ SW _ EN signal of the flyback power conversion control circuit 6, and a high level driving signal is given to the MCU _ KL30_ SW _ POWER CTRL signal of the POWER supply enabling control circuit 4 of the flyback control chip to realize the control of the work of the flyback control chip U1, therefore, the transformer 7, the flyback first output circuit 8, the flyback first bypass output circuit 9, the flyback second output circuit 10 and the flyback second output sampling circuit 11 can work and output normally. And the 5V _ MCU in the first path of flyback bypass output circuit 9 is normally powered. The output of VOUT1 of the flyback first output circuit 8 can be bypassed, and VIN is used for supplying power to be output as VOUT1 and is not output by a flyback power supply any more. When the flyback power supply normally works, self-locking can be achieved, the MCU does not need to pull up the MCU _ KL30_ SW _ CTRL signal all the time, and the MCU sets the MCU _ KL30_ SW _ CTRL to be in an input mode and presents a high-impedance state.

The duty ratio of an 8-pin (GDRV) driving signal of the control chip U1 is reduced, and the purpose of overcurrent protection is achieved.

When overcurrent occurs, the overcurrent protection detection resistor R29 can detect the overcurrent and feed back the overcurrent protection detection resistor R29 to a 7 pin (ISNS) of the flyback control chip U1 to perform action response, and the duty ratio of a corresponding 8 pin (GDRV) driving signal of the flyback control chip U1 is reduced, so that the purpose of overcurrent protection is achieved.

Whether short-circuit protection, overvoltage protection and undervoltage protection occur or not is judged by detecting KL30_ SW _ AD and VOUT2_ AD signal sampling.

When detecting that the KL30_ SW _ AD and VOUT2_ AD signals exceed the overvoltage and undervoltage protection threshold, the MCU makes a judgment and reports the judgment, and meanwhile, the MCU _ KL30_ SW _ CTRL is pulled down to turn off the Q6, and the Q2 is correspondingly turned off, so that the flyback power supply cannot be caused by overvoltage and undervoltage loss devices; q6 is a Q2 control MOS.

When the detected KL30_ SW _ AD signal is suddenly pulled down to be very low, the primary side short circuit of the transformer 7 can be judged, the MCU can make judgment and report, software acts faster on hardware, Q6 is turned off, self-locking is realized, and Q2 is correspondingly turned off, so that the primary side short circuit of the transformer 7 cannot lose devices.

When detecting that the VOUT2_ AD signal is suddenly pulled down to be very low, the secondary side of the transformer 7 can be judged to be short-circuited, the MCU can make judgment and report, the software acts to pull down the MCU _ KL30_ SW _ CTRL to turn off the Q6, and the Q2 is correspondingly turned off, so that the secondary side of the transformer 7 is short-circuited and does not wear devices.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.

Claims

1. A protection circuit of a flyback power supply is characterized in that: the flyback control circuit comprises an input filter protection circuit (1), a protection circuit (2), an input sampling circuit (3), a flyback control chip power supply enabling control circuit (4), a flyback power supply conversion absorption circuit (5) and a transformer (7), wherein the input filter protection circuit (1), the protection circuit (2) and the flyback control chip power supply enabling control circuit (4) are connected with one another, and the flyback control chip power supply enabling control circuit (4) is connected with a flyback power supply conversion control circuit (6); the protection circuit (2), the input sampling circuit (3), the flyback power conversion absorption circuit (5) and the flyback power conversion control circuit (6) are connected with the input end of the transformer (7); the output end of the transformer (7) is connected with a flyback first output circuit (8) and a flyback second output circuit (10).

2. The protection circuit of a flyback power supply of claim 1, wherein: the input end of the transformer (7) is provided with a pin 1 and a pin 2, wherein the protection circuit (2), the input sampling circuit (3), the flyback power conversion absorption circuit (5) are connected with the pin 1, and the flyback power conversion absorption circuit (5), the flyback power conversion control circuit (6) are connected with the pin 2.

3. The protection circuit of a flyback power supply of claim 1, wherein: and a filter supporting capacitor C4 is connected between the protection circuit (2) and the flyback power supply conversion absorption circuit (5).

4. The protection circuit of a flyback power supply of claim 1, wherein: the output end of the transformer (7) is provided with a pin 9 and a pin 10, the flyback first-path output circuit (8) is connected with the pin 9 and the pin 10, and the flyback first-path output circuit is connected with the flyback first-path bypass output circuit (9).

5. The protection circuit of a flyback power supply of claim 1, wherein: the output end of the transformer (7) is provided with a pin 6 and a pin 7, the flyback second output circuit (10) is connected with the pin 6 and the pin 7, and the flyback second output circuit (10) is connected with the flyback second output sampling circuit (11) and the flyback power supply conversion control circuit (6).