CN220492635U

CN220492635U - Flyback switching circuit and flyback switching power supply

Info

Publication number: CN220492635U
Application number: CN202321816223.6U
Authority: CN
Inventors: 斯建
Original assignee: Aux Air Conditioning Co Ltd; Ningbo Aux Electric Co Ltd
Current assignee: Aux Air Conditioning Co Ltd; Ningbo Aux Electric Co Ltd
Priority date: 2023-07-11
Filing date: 2023-07-11
Publication date: 2024-02-13
Anticipated expiration: 2033-07-11

Abstract

The utility model provides a flyback switch circuit and a flyback switch power supply, which relate to the field of electronic circuits, wherein a flyback switch main module, a high-voltage starting module and a high-voltage direct current input end of a high-voltage protection module are all connected with the high-voltage direct current power supply, the flyback switch module comprises a power management IC for controlling the on and off of the flyback switch module, and an output end of the high-voltage protection module is connected with a charging output end of the high-voltage starting module and a starting voltage input end of the power management IC, so that when the flyback switch main module is electrified for the first time, the high-voltage starting module can output starting voltage to the starting voltage input end of the power management IC through the high-voltage direct current power supply after charging so as to start the power management IC to work, and when the high-voltage protection module detects that the voltage of the high-voltage direct current voltage is overhigh, the high-voltage protection module outputs pull-down voltage so as to drive the power management IC to stop working, thereby realizing high-voltage starting and overvoltage protection of the flyback switch circuit.

Description

Flyback switching circuit and flyback switching power supply

Technical Field

The utility model relates to the field of electronic circuits, in particular to a flyback switching circuit and a flyback switching power supply.

Background

The flyback switching power supply means that when the primary winding of the transformer is excited by the direct current pulse voltage, the secondary winding of the transformer does not provide a power output to the load, but provides a power output to the load only after the excitation voltage of the primary winding of the transformer is turned off. Flyback switching power supplies are commonly used in the air conditioning industry.

Traditional integrated flyback switching power supply chips (power switch tube and power management IC are integrated) such as TNY278 of PI company, three-reclamation STR6A series and the like, and the power supply chips have certain limitation in application and cannot perform overvoltage protection and the like when the power supply receives lightning surge impact.

Disclosure of Invention

The utility model aims to provide a flyback switching circuit and a flyback switching power supply, which can solve the problem that an existing flyback switching power supply chip cannot perform overvoltage protection when receiving lightning surge impact.

The utility model provides the following technical scheme:

in a first aspect, an embodiment of the present utility model provides a flyback switch circuit, including a flyback switch main module, a high voltage starting module, and a high voltage protection module, where the flyback switch main module includes a power management IC;

the high-voltage direct current input end of the flyback switch main module, the high-voltage direct current input end of the high-voltage starting module and the high-voltage direct current input end of the high-voltage protection module are all used for being connected with a high-voltage direct current power supply;

the output end of the high-voltage protection module is respectively connected with the charging output end of the high-voltage starting module and the starting voltage input end of the power management IC;

the power management IC is used for outputting a control signal for driving the flyback switch main module to be turned on and off;

the high-voltage starting module is used for outputting starting voltage to the starting voltage input end of the power management IC after the high-voltage direct-current power supply is charged when the flyback switch main module is electrified for the first time so as to supply power for the power management IC;

and the high-voltage protection module is used for outputting a pull-down voltage from the output end of the high-voltage protection module when the voltage input by the high-voltage direct-current power supply exceeds a voltage threshold value so as to pull down the input voltage of the power management IC.

Further, the flyback switch main module further comprises an N-type MOS tube and a transformer;

the base electrode of the N-type MOS tube is connected with the PWM output end of the power management IC, the drain electrode of the N-type MOS tube is connected with one end of the primary winding of the transformer, and the grid electrode of the N-type MOS tube is grounded;

the starting voltage input end of the power management IC is respectively connected with one end of the first secondary winding of the transformer and the charging output end of the high-voltage starting module;

the transformer, the other end of primary winding is used for being connected with high-voltage direct current power supply, the other end ground of first secondary winding is connected with ground, and the second secondary winding is used for being connected with the load.

Further, the high-voltage protection module comprises an optocoupler, an adjustable shunt voltage stabilizer, a second current-limiting resistor, a first voltage-dividing resistor and a second voltage-dividing resistor;

one end of the first voltage dividing resistor and one end of the second current limiting resistor are connected with a high-voltage direct current input end of the high-voltage protection module, and the other end of the first voltage dividing resistor is connected with one end of the second voltage dividing resistor and a reference end of the adjustable shunt voltage stabilizer respectively;

the anode of the adjustable shunt regulator and the other end of the second voltage dividing resistor are grounded;

the anode of the photodiode of the optocoupler is connected with the other end of the second current limiting resistor, and the cathode of the photodiode of the optocoupler is connected with the cathode of the adjustable shunt regulator;

and the collector electrode of the phototriode of the optocoupler is connected with the output end of the high-voltage protection module, and the emitter electrode of the phototriode is grounded.

Further, the high-voltage starting module comprises a first energy storage element, a voltage stabilizing diode, a clamping diode, an NPN triode, a bias resistor and a first current limiting resistor;

the anode of the clamping diode, the emitter of the NPN triode and the anode of the first energy storage element are connected with the charging output end of the high-voltage starting module, and one end of the first current limiting resistor and one end of the bias resistor are connected with the high-voltage direct-current input end of the high-voltage starting module;

the other end of the first current limiting resistor is connected with the collector electrode of the NPN triode, and the other end of the bias resistor is respectively connected with the base electrode of the NPN triode, the cathode of the clamping diode and the cathode of the zener diode;

and the anode of the voltage stabilizing diode and the cathode of the first energy storage element are grounded.

Further, the flyback switching circuit further comprises a voltage absorbing circuit;

the first absorption end of the voltage absorption circuit is connected with the high-voltage direct-current input end of the flyback switch main module, and the second absorption end of the voltage absorption circuit is connected with the drain electrode of the N-type MOS tube, so that peak voltage generated by leakage inductance of the transformer is absorbed when the N-type MOS tube is turned off.

Further, the flyback switch main module further comprises a first rectifying diode and a third current limiting resistor;

the anode of the first rectifying diode is connected with one end of the first secondary winding of the transformer, and the cathode of the first rectifying diode is connected with one end of the third current limiting resistor;

the other end of the third current limiting resistor is connected with the starting voltage input end of the power management IC, and the other end of the first secondary winding of the transformer is grounded.

Further, the flyback switch main module further comprises a rectifying voltage-stabilizing unit;

the input end of the rectifying and voltage stabilizing unit is connected with one end of the second secondary winding of the transformer, and the output end of the rectifying and voltage stabilizing unit is used for being connected with a load;

the other end of the second secondary winding of the transformer is grounded.

Further, the rectifying and voltage stabilizing unit comprises a second rectifying diode and a second energy storage piece;

the anode of the second rectifying diode is connected with the input end of the rectifying and voltage stabilizing unit, and the cathode of the second rectifying diode is connected with the input end of the rectifying and voltage stabilizing unit and the anode of the second energy storage piece respectively;

the positive electrode of the second energy storage piece is grounded.

In a second aspect, an embodiment of the present utility model provides a flyback switching power supply, including a high-voltage dc power supply, and a flyback switching circuit as described in the first aspect.

The flyback switch circuit and the flyback switch power supply provided by the utility model have the advantages that the flyback switch main module, the high-voltage starting module and the high-voltage direct current input end of the high-voltage protection module are all connected with the high-voltage direct current power supply, the flyback switch module comprises the power management IC for controlling the on and off of the flyback switch module, and the output end of the high-voltage protection module is connected with the charging output end of the high-voltage starting module and the starting voltage input end of the power management IC, so that when the flyback switch main module is electrified for the first time, the high-voltage starting module can output starting voltage to the starting voltage input end of the power management IC through the high-voltage direct current power supply after charging so as to start the power management IC to work, and when the high-voltage protection module detects that the voltage of the high-voltage direct current voltage is overhigh, the high-voltage protection module outputs the pull-down voltage for pulling down the power management IC so as to drive the power management IC to stop working, thereby realizing high-voltage starting and overvoltage protection of the flyback switch circuit, and greatly improving the performance of the flyback switch power supply.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present utility model, the drawings that are needed in the embodiments will be briefly described below, it being understood that the following drawings only illustrate some embodiments of the present utility model and should not be considered as limiting the scope, and other related drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

Fig. 1 is a block schematic diagram of a flyback switching circuit according to an embodiment of the present utility model.

Fig. 2 is a schematic circuit diagram of a reaction switch circuit according to the present embodiment of the disclosure.

Reference numerals illustrate: 10-flyback switch main module; Q1-N type MOS tube; a T1-transformer; d3—a first rectifier diode; r7-a third current limiting resistor; 101-rectifying and stabilizing unit; d2—a second rectifier diode; e2—a second energy storage element; 20-a high voltage start module; r2-a first current limiting resistor; r6-bias resistor; a D4-clamp diode; d5-a zener diode; e1-a first energy storage element; Q2-NPN triode; 30-a high voltage protection module; OC 1-optocoupler; r3-a second current limiting resistor; r4 is a first voltage dividing resistor; r5-a second voltage dividing resistor; TL 1-an adjustable shunt regulator; 40-a voltage sink circuit; r1 is a protection resistor; c1-absorption capacitance; d1-anti-reverse diode.

Detailed Description

For the purpose of making the objects, technical solutions and advantages of the embodiments of the present utility model more apparent, the technical solutions of the embodiments of the present utility model will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present utility model, and it is apparent that the described embodiments are some embodiments of the present utility model, but not all embodiments. The components of the embodiments of the present utility model generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.

Thus, the following detailed description of the embodiments of the utility model, as presented in the figures, is not intended to limit the scope of the utility model, as claimed, but is merely representative of selected embodiments of the utility model. All other embodiments, based on the embodiments of the utility model, which are apparent to those of ordinary skill in the art without inventive faculty, are intended to be within the scope of the utility model.

It should be noted that: like reference numerals and letters denote like items in the following figures, and thus once an item is defined in one figure, no further definition or explanation thereof is necessary in the following figures.

In the description of the present utility model, it should be understood that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," "outer," and the like indicate orientations or positional relationships based on those shown in the drawings, or those conventionally put in place when the inventive product is used, or those conventionally understood by those skilled in the art, merely for convenience in describing the present utility model and simplifying the description, and do not indicate or imply that the apparatus or element to be referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present utility model.

Furthermore, the terms "first," "second," "third," and the like are used merely to distinguish between descriptions and should not be construed as indicating or implying relative importance.

In the description of the present utility model, it should also be noted that, unless explicitly specified and limited otherwise, the terms "disposed," "mounted," "connected," and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present utility model will be understood in specific cases by those of ordinary skill in the art.

Traditional integrated flyback switching power supply chips (power switch tube and power management IC are integrated) such as TNY278 of PI company, three-reclamation STR6A series and the like, and the power supply chips have certain limitations in application: because the chip has no high-voltage protection function, overvoltage protection and the like cannot be performed when the power supply receives lightning surge impact.

Based on the above consideration, the embodiment of the utility model improves a flyback switching circuit, which can perform overvoltage protection when a flyback switching power supply chip receives lightning surge impact or overhigh voltage.

In one possible embodiment, a flyback switching circuit is provided, and referring to fig. 1, the flyback switching circuit may include a flyback switching main module 10, a high voltage start module 20, and a high voltage protection module 30, and the flyback switching main module 10 may include a power management IC.

The power management IC is configured to output a control signal for driving the on and off of the flyback switch main module 10.

The high-voltage dc input end of the flyback switch main module 10, the high-voltage dc input end of the high-voltage starting module 20 and the high-voltage dc input end of the high-voltage protection module 30 are all used for being connected with the high-voltage dc power supply Vcc1, i.e. the high-voltage dc input ends of the flyback switch main module 10, the high-voltage starting module 20 and the high-voltage protection module 30 are connected with the same high-voltage dc power supply.

The output end Op2 of the high voltage protection module 30 is connected to the charging output end Op1 of the high voltage starting module 20 and the starting voltage Input end Input1 of the power management IC, respectively, that is, the output end Op2 of the high voltage protection module 30, the charging output end Op1 of the high voltage starting module 20 and the starting voltage Input end Input1 of the power management IC are connected to the same equipotential point.

The high voltage starting module 20 is configured to output a starting voltage to the starting voltage Input terminal Input1 of the power management IC after charging by the high voltage dc power supply when the flyback switch main module 10 is powered on for the first time, so as to supply power to the power management IC.

After the power management IC is charged by the high voltage starting module 20, the flyback switch main module 10 can be controlled to be turned on or turned off according to the environmental condition or the circuit state of the flyback switch main module 10.

The high voltage protection module 30 is configured to output a pull-down voltage from the output terminal Op2 of the high voltage protection module 30 to pull down the input voltage of the power management IC when the voltage input by the high voltage dc power supply exceeds a voltage threshold.

Since the output terminal Op2 of the high voltage protection module 30, the charging output terminal Op1 of the high voltage starting module 20 and the starting voltage Input terminal Input1 of the power management IC are connected to the same equipotential point, when the high voltage protection module 30 outputs the pull-down voltage, both the charging output terminal Op2 of the high voltage starting module 20 and the starting voltage Input1 of the power management IC are pulled down, the power management IC cannot operate due to no voltage, and the flyback switch main module 10 is turned off accordingly.

The working principle of the flyback switching circuit is as follows: when the flyback switch main module 10 is powered on for the first time, the high-voltage starting module 20 charges through the high-voltage direct-current power supply, outputs starting voltage to the power management IC after charging, starts the power management IC, enables the flyback switch main module 10 to start working, and if the voltage of the high-voltage direct-current power supply is too high in the working process, the high-voltage protection module 30 outputs starting voltage for pulling the low-voltage power management IC, the power management IC stops working, and the flyback switch main module 10 is turned off accordingly.

Through the arrangement, the high-voltage starting and overvoltage protection of the flyback switching circuit are realized, and the performance of the flyback switching power supply is greatly improved.

Further, referring to fig. 2, the flyback switch main module 10 may further include an N-type MOS transistor Q1 and a transformer T1.

The base electrode of the N-type MOS tube Q1 is connected with the PWM output end of the power management IC, the drain electrode of the N-type MOS tube Q1 is connected with one end of the primary winding of the transformer T1, and the grid electrode of the N-type MOS tube Q1 is grounded.

The start voltage input terminal of the power management IC is connected to one end of the first secondary winding of the transformer T1 and the charge output terminal Op1 of the high voltage start module 20, respectively.

And the other end of the primary winding of the transformer T1 is used for being connected with a high-voltage direct-current power supply, the other end of the first secondary winding is grounded, and the second secondary winding is used for being connected with a load.

The power management IC controls the on and off of the N-type MOS transistor Q1 by outputting PWM waves from a PWM end.

Through the arrangement, when the power management CI outputs a high-level signal to the N-type MOS transistor Q1, the N-type MOS switch transistor is conducted, and the transformer T1 stores energy through the primary winding; when the power management IC outputs a low-level signal to the N-type MOS tube Q1, the N-type MOS tube Q1 is turned off, the first secondary winding and the second secondary winding of the transformer T1 release energy, the output electric energy of the first secondary winding is used as the starting voltage of the power management IC, and the output electric energy of the second secondary winding is used as the power supply of the load.

It should be noted that, the N-type MOS transistor Q1 may be replaced by another switching transistor, for example, a P-type MOS transistor may also be a triode, and the N-type MOS transistor Q1 is merely an example, but not limited to only.

When the N-type MOS transistor Q1 is turned off, since the magnetic force lines generated by the winding of the transformer T1 cannot pass through the secondary winding to generate leakage inductance (i.e., leakage inductance), in order to avoid the influence of the leakage inductance, in a possible embodiment, referring to fig. 2, the flyback switching circuit may further include a voltage absorbing circuit 40.

The first absorption end of the voltage absorption circuit 40 is connected with the high-voltage direct-current input end of the flyback switch main module 10, and the second absorption end of the voltage absorption circuit 40 is connected with the drain electrode of the N-type MOS transistor Q1, so as to absorb peak voltage generated by leakage inductance of the transformer T1 when the N-type MOS transistor Q1 is turned off.

Further, referring to fig. 2, the voltage absorbing circuit 40 may include an absorbing capacitance C1, a protection resistor R1, and an anti-reflection diode D1.

The anti-reverse diode D1 has an anode connected to the second absorption terminal of the voltage absorption circuit 40, and a cathode connected to one terminal of the protection resistor R1 and one terminal of the absorption capacitor C1, respectively.

The other end of the protection resistor R1 and the other end of the absorption capacitor C1 are both connected to the first absorption end of the voltage absorption circuit 40.

When the N-type MOS tube Q1 is turned off, leakage inductance generated by the transformer T1 flows into the absorption capacitor C1 and the protection resistor R1 through the anti-reflection diode D1 and is absorbed by the absorption capacitor C1 and the protection resistor R1, so that leakage inductance absorption is realized.

Further, since there may be ac power in the output of the first secondary winding of the transformer T1, in order to avoid that the power outputted from the first secondary winding of the transformer T1 can supply power to the power management IC, referring to fig. 2, the flyback switch main module 10 may further include a first rectifying diode D3 and a third current limiting resistor R7.

And the anode of the first rectifying diode D3 is connected with one end of the first secondary winding of the transformer T1, and the cathode of the first rectifying diode D is connected with one end of the third current limiting resistor R7.

The other end of the third current limiting resistor R7 is connected with the starting voltage Input end Input1 of the power management IC, and the other end of the first secondary winding of the transformer T1 is grounded.

The electric energy output by the first secondary winding of the transformer T1 is converted into direct-current electric energy through the first rectifying diode D3, and the current value is reduced through the third current limiting resistor R7, so that the power management IC can be supplied with power.

In one possible embodiment, in order to enable the third winding of the transformer T1 to output voltage-stabilized electrical energy, to safely power the load. Referring to fig. 2, the flyback switch main module 10 may further include a rectifying and voltage stabilizing unit 101.

The rectifying and voltage stabilizing unit 101 has an input end connected to one end of the second secondary winding of the transformer T1 and an output end for connection to a load.

The other end of the second secondary winding of the transformer T1 is grounded.

Further, the rectifying and voltage stabilizing unit 101 includes a second rectifying diode D2 and a second energy storage element E2;

the anode of the second rectifying diode D2 is connected with the input end of the rectifying and voltage stabilizing unit 101, and the cathode is respectively connected with the input end of the rectifying and voltage stabilizing unit 101 and the anode of the second energy storage element E2.

The positive electrode of the second energy storage element E2 is grounded.

The second energy storage element E2 may be an energy storage capacitor, or may be another energy storage element.

Through the arrangement, after the electric energy output by the second secondary winding of the transformer T1 is rectified by the second rectifying diode D2, the second energy storage element E2 is charged, and then the electric energy with stable voltage is output by the second energy storage element E2 to supply power for a load.

When the flyback switch main module 10 is powered on for the first time, the first secondary winding of the transformer T1 is not output, and the starting voltage of the power management IC is zero, so that the power management IC cannot work. Therefore, in order to enable the power management IC to operate quickly when the flyback switch main module 10 is first powered on, a function of charging and discharging energy is introduced to the high voltage starting module 20.

Referring to fig. 2, the high voltage starting module 20 may include a first energy storage element E1, a zener diode D5, a clamping diode D4, an NPN transistor Q2, a bias resistor R6, and a first current limiting resistor R2.

The anode of the clamping diode D4, the emitter of the NPN triode Q2 and the anode of the first energy storage element E1 are connected with a charging output end Op1 of the high-voltage starting module 20, and one end of the first current limiting resistor R2 and one end of the bias resistor R6 are connected with a high-voltage direct current input end of the high-voltage starting module 20.

The other end of the first current limiting resistor R2 is connected with the collector of the NPN triode Q2, and the other end of the bias resistor R6 is respectively connected with the base of the NPN triode Q2, the cathode of the clamping diode D4 and the cathode of the voltage stabilizing diode D5.

The anode of the zener diode D5 and the cathode of the first energy storage element E1 are grounded.

The first energy storage element E1, the voltage stabilizing diode D5, the clamping diode D4, the NPN triode Q2, the bias resistor R6 and the first current limiting resistor R2 form a charging circuit.

The first energy storage element E1 may be an electrolytic capacitor, or may be another energy storage element. The zener diode D5 may be a 20V zener diode D5.

The working principle of the high-voltage starting module 20 is as follows: when the flyback switch main module 10 is powered on for the first time, the high-voltage direct-current power supply provides bias voltage for the NPN triode Q2 through the bias resistor R6, so that the NPN triode Q2 is conducted, the high-voltage direct-current power supply can charge the first energy storage element E1 through the first current limiting resistor R2, when the voltage of the first energy storage element E1 is larger than 20.7V (assuming that the conduction voltage drop of the clamping diode D4 is 0.7V), the clamping diode D4 is conducted in the forward direction, the voltage stabilizing diode D5 is broken down in the reverse direction, the NPN triode Q2 is clamped at 20V, at the moment, the base-collector voltage of the NPN triode Q2 is-0.7, so that the NPN triode Q2 is cut off, the first energy storage element E1 provides starting voltage for the power management IC from the charging output end, the power management IC starts working, and the high-voltage starting is completed.

After the first power-on start, the power management IC starts to operate, and then the second secondary winding of the transformer T1 supplies power to the first energy storage element E1 and the power management IC.

Further, in order to enable overvoltage protection, referring to fig. 2, the high voltage protection module 30 may include an optocoupler OC1, an adjustable shunt regulator TL1, a second current limiting resistor R3, a first voltage dividing resistor R4, and a second voltage dividing resistor R5. It should be appreciated that optocoupler OC1 includes a photodiode and a phototransistor.

One end of the first voltage dividing resistor R4 and one end of the second current limiting resistor R3 are connected with a high-voltage direct-current input end of the high-voltage protection module 30, and the other end of the first voltage dividing resistor R4 is connected with one end of the second voltage dividing resistor R5 and a reference end of the adjustable shunt regulator TL1 respectively.

The other ends of the anode of the adjustable shunt regulator TL1 and the second voltage dividing resistor R5 are grounded.

An anode of the photodiode of the optocoupler OC1 is connected with the other end of the second current limiting resistor R3, and a cathode of the photodiode of the optocoupler OC1 is connected with a cathode of the adjustable shunt regulator TL 1.

The collector of the phototriode of the optical coupler OC1 is connected with the output end Op2 of the high-voltage protection module 30, and the emitter is grounded.

It should be appreciated that the sum of the voltages across the first voltage dividing resistor R4 and the second voltage dividing resistor R5 is equal to the output voltage value of the high voltage dc power supply. And, the adjustable shunt regulator TL1 may be replaced by a controller, a comparator, or the like, and the adjustable shunt regulator TL1 is not limited only. Similarly, the optocoupler OC1 may be replaced by other switching transistors, such as a MOS transistor and a triode, which are not limited in this embodiment.

The adjustable shunt regulator TL1 may be TL431, and the voltage value of the reference terminal of the adjustable shunt regulator TL1 may be expressed as:

the working principle of the high-voltage protection module 30 is as follows: when the reference end of the adjustable shunt regulator TL1 exceeds a threshold (assuming 2.5V), the cathode of the adjustable shunt regulator TL1 is turned on, so that the photodiode of the optocoupler OC1 emits light, and the phototransistor of the optocoupler OC1 is turned on when the photodiode emits light, so that a pull-down voltage is generated at the equipotential point where the high voltage dc input end of the flyback switch main module 10, the high voltage dc input end of the high voltage starting module 20, and the high voltage dc input end of the high voltage protection module 30 are connected, and the power management IC stops working accordingly, so that the high voltage starting module 20 cannot charge the first energy storage element E1. On the contrary, the phototriode of the optical coupler OC1 is cut off, and the starting voltage output end of the power management IC is not at a low level and works normally.

Through setting up high voltage protection module 30, when detecting that input voltage is too high, opto-coupler OC1 switches on and charges for first energy storage E1, makes the first secondary winding of high voltage starting module 20 and transformer T1 all unable for power management IC power supply, and power management IC also can' T work to prevent that high voltage direct current power supply voltage from being too high leads to flyback switching power supply, realize overvoltage protection.

In the flyback switch circuit, the external high-voltage starting module 20 and the external high-voltage protection module 30 control the Vcc power supply (starting voltage) of the power management IC of the flyback switch main module 10, so as to realize input overvoltage protection. In addition, the high-voltage starting pin of the power management IC is not needed, and the input voltage range can be greatly widened by adjusting the types of the N-type MOS transistor Q1, the NPN-type triode Q2, the anti-reflection diode D1 and the like.

Based on the same concept as the flyback switching circuit described above, in one possible embodiment, there is also provided a flyback switching power supply, which may include a high-voltage direct-current power supply, and the flyback switching circuit provided in the above embodiment.

The flyback switching power supply can output the starting voltage to the starting voltage input end of the power management IC by the high-voltage starting module 20 after the flyback switching main module 10 is charged for the first time, so as to start the power management IC to work, and the high-voltage protection module 30 outputs the pulling-down voltage for pulling down the power management IC when detecting that the voltage of the high-voltage direct-current voltage is too high, so as to drive the power management IC to stop working, thereby realizing high-voltage starting and overvoltage protection of the flyback switching circuit, and greatly improving the performance of the flyback switching power supply.

The above description is only of the preferred embodiments of the present utility model and is not intended to limit the present utility model, and various modifications and variations may be made to the present utility model by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present utility model should be included in the protection scope of the present utility model.

Claims

1. The flyback switch circuit is characterized by comprising a flyback switch main module, a high-voltage starting module and a high-voltage protection module, wherein the flyback switch main module comprises a power management IC;

2. The flyback switch circuit of claim 1 wherein the flyback switch main module further comprises an N-type MOS transistor and a transformer;

3. The flyback switching circuit according to claim 1 or 2, wherein the high voltage protection module comprises an optocoupler, an adjustable shunt regulator, a second current limiting resistor, a first voltage dividing resistor and a second voltage dividing resistor;

4. The flyback switching circuit of claim 1 or 2, wherein the high voltage starting module comprises a first energy storage element, a zener diode, a clamping diode, an NPN transistor, a bias resistor and a first current limiting resistor;

5. The flyback switching circuit of claim 2 further comprising a voltage sink circuit;

6. The flyback switching circuit of claim 2 wherein the flyback switching master module further comprises a first rectifying diode and a third current limiting resistor;

7. The flyback switching circuit according to claim 2 or 6, wherein the flyback switching main module further comprises a rectifying and voltage stabilizing unit;

the other end of the second secondary winding of the transformer is grounded.

8. The flyback switching circuit of claim 5 wherein the voltage sink circuit comprises a sink capacitor, a protection resistor, and an anti-reverse diode;

the anode of the anti-reverse diode is connected with the second absorption end of the voltage absorption circuit, and the cathode of the anti-reverse diode is respectively connected with one end of the protection resistor and one end of the absorption capacitor;

the other end of the protection resistor and the other end of the absorption capacitor are connected with the first absorption end of the voltage absorption circuit.

9. The flyback switching circuit of claim 7 wherein the rectifying and voltage stabilizing unit comprises a second rectifying diode and a second energy storage element;

the positive electrode of the second energy storage piece is grounded.

10. A flyback switching power supply comprising a high voltage dc power supply and a flyback switching circuit according to any one of claims 1 to 9.