CN216699819U - Switching power supply control protection circuit - Google Patents

Abstract

The utility model discloses a switch power supply control protection circuit, comprising: the PWM control circuit is electrically connected with the corresponding end of the switching power supply protection circuit; the switch power supply protection circuit comprises a current-limiting protection circuit, a surge suppression protection circuit, a common-mode inductor circuit, a rectifying whole bridge circuit, an electrolytic capacitor circuit and an RCD absorption circuit; one end of the current-limiting protection circuit is connected with one end of the commercial power, and the other end of the current-limiting protection circuit is electrically connected with the corresponding end of the surge suppression protection circuit; the other end of the commercial power is also electrically connected with the corresponding end of the surge suppression protection circuit; and the corresponding end of the surge suppression protection circuit is also electrically connected with the corresponding ends of the common-mode inductance circuit, the rectifying and rectifying bridge circuit, the electrolytic capacitor circuit and the RCD absorption circuit in sequence. The utility model has high safety, and the fuse plays the role of current limiting protection; the surge suppression protection circuit plays a role in surge suppression protection; the surge suppression protection circuit can realize the protection of a post-stage circuit; the common mode inductance circuit is used for restraining high-speed signal line production.

Description

Switching power supply control protection circuit

Technical Field

The utility model relates to the technical field of switching power supplies, in particular to a switching power supply control protection circuit.

Background

The switching power supply is a power supply which utilizes modern power electronic technology to control the on-off time ratio of a switching tube and maintain stable output voltage, and generally consists of a Pulse Width Modulation (PWM) control IC and a MOSFET. With the development and innovation of power electronic technology, the technology of the switching power supply is continuously innovated. At present, the switching power supply is widely applied to almost all electronic devices with the characteristics of small size, light weight and high efficiency, and is an indispensable power supply mode for the rapid development of the electronic information industry at present.

The existing switching power supply is lack of current-limiting protection, can not inhibit circulating surge current, can not inhibit electromagnetic waves generated by a high-speed signal wire from radiating and emitting outwards, has poor safety performance and is easy to cause potential safety hazards; the conventional PWM control circuit has the following disadvantages: the circuit power supply is easily disturbed, and there is no power supply isolation protection circuit, and the MOS tube can not be controlled to be switched on and switched off, and the output power can not be adjusted, and the supplied voltage is unstable, and the circuit protection is poor.

SUMMERY OF THE UTILITY MODEL

Aiming at the problems in the prior art, the utility model provides a switching power supply control protection circuit.

In order to achieve the purpose, the technical scheme of the utility model is as follows:

the utility model provides a switch power supply control protection circuit, comprising: the PWM control circuit is electrically connected with the corresponding end of the switching power supply protection circuit; the switch power supply protection circuit comprises a current-limiting protection circuit, a surge suppression protection circuit, a common-mode inductor circuit, a rectifying whole bridge circuit, an electrolytic capacitor circuit and an RCD absorption circuit; one end of the current-limiting protection circuit is connected with one end of the commercial power, and the other end of the current-limiting protection circuit is electrically connected with the corresponding end of the surge suppression protection circuit; the other end of the commercial power is also electrically connected with the corresponding end of the surge suppression protection circuit; the corresponding end of the surge suppression protection circuit is also electrically connected with the corresponding ends of the common-mode inductance circuit, the rectifying and rectifying bridge circuit, the electrolytic capacitor circuit and the RCD absorption circuit in sequence; the PWM control circuit comprises a PWM control chip, a PWM output circuit, a voltage stabilizing circuit, an optical coupling circuit and a mos tube circuit; the corresponding end of the PWM control chip is electrically connected with the optical coupling circuit, the voltage stabilizing circuit and the PWM output circuit respectively; and the corresponding end of the PWM output circuit is electrically connected with the mos tube circuit.

Preferably, the current-limiting protection circuit includes a fuse F1, and one end of the fuse F1 is electrically connected to one end of the utility power; the surge suppression protection circuit comprises a thermistor NTC1 and a piezoresistor MOV 1; one end of the thermistor NTC1 is electrically connected with the other end of the fuse F1, and the other end of the thermistor NTC1 is electrically connected with one end of the piezoresistor MOV1 respectively; the other end of the piezoresistor MOV1 is electrically connected with the other end of the commercial power.

Preferably, the common-mode inductance circuit comprises a diode D1, a diode D2, a common-mode inductance LF1, a common-mode inductance LF2, a resistor R1, a resistor R1A, a resistor R2, a resistor R2A, and a capacitor CX 1;

the common-mode inductor LF1 comprises a first coil and a second coil which are wound on a magnetic core in parallel, and the winding directions of the first coil and the second coil are opposite; the common-mode inductor LF2 comprises a third coil and a fourth coil which are wound on a magnetic core in parallel, and the winding directions of the third coil and the fourth coil are opposite;

one end of the diode D1 is electrically connected with the other end of the thermistor NTC1, one end of the varistor MOV1 and one end of the first coil respectively, and the other end of the diode D2 is electrically connected; the other end of the diode D2 is respectively and electrically connected with the other end of the piezoresistor MOV1 and the corresponding end of one end of the second coil; the other end of the first coil is electrically connected with one end of a resistor R1, one end of a resistor R1A, one end of a capacitor CX1 and one end of a third coil respectively; the other end of the second coil is respectively and electrically connected with one end of a resistor R2, one end of a resistor R2A, the other end of a capacitor CX1 and one end of a fourth coil; the other end of the resistor R1 is electrically connected with the other end of the resistor R2, the other end of the resistor R1A and the other end of the resistor R2A respectively; the other end of the third coil and the other end of the fourth coil are respectively and correspondingly electrically connected with the corresponding end of the rectifying whole bridge circuit.

Preferably, the electrolytic capacitor circuit comprises a capacitor C10, one end of the capacitor C10 is electrically connected to the fourth corresponding end of the rectifying and rectifying bridge circuit and grounded, and the other end is electrically connected to the second corresponding end of the rectifying and rectifying bridge circuit and the corresponding end of the RCD absorption circuit.

Preferably, the RCD absorption circuit includes a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R7, a resistor R8, a resistor R9, a capacitor C1, a diode D6, and a diode D6; one end of the resistor R3 is electrically connected with a second corresponding end of the rectifying whole bridge circuit, the other end of the capacitor C10, one end of the resistor R4 and one end of the capacitor C1 respectively, and the other end of the resistor R3 is electrically connected with one end of the resistor R5, the other end of the resistor R4 and one end of the resistor R6 respectively; the other end of the resistor R5 is electrically connected with the other end of the resistor R6, one end of the diode D6, one end of the resistor R7, one end of the resistor R8 and one end of the resistor R9 respectively; the other end of the capacitor C1 is electrically connected with the other ends of the resistor R7, the resistor R8 and the resistor R9 respectively.

Preferably, the PWM output circuit includes a resistor R13A, a diode D3, a triode Q1, a resistor R11, and a resistor R12; one end of the resistor R13A is electrically connected with the corresponding end of the PWM control chip, and the other end of the resistor R13A is electrically connected with one end of the diode D3 and the first corresponding end of the triode Q1 respectively; a second corresponding end of the triode Q1 is electrically connected with the other end of the diode D3, one end of the resistor R11 and one end of the resistor R12 respectively; the first corresponding end of the triode Q1 is also electrically connected with the other end of the resistor R11; the other end of the resistor R12 is electrically connected with the corresponding end of the mos tube circuit; the model of the PWM control chip is set to be LD 5760.

Preferably, the voltage stabilizing circuit comprises a diode D4, a resistor R14 and a capacitor C9; the sixth corresponding end of the PWM control chip is electrically connected with one end of a capacitor C9 and one end of a diode D4 respectively; the other end of the diode D4 is electrically connected with one end of the resistor R14.

Preferably, the optical coupling circuit comprises an optical coupling isolator U4A and a capacitor C4; and a second corresponding end of the PWM control chip is electrically connected with an optocoupler isolator U4A and a corresponding end of a capacitor C4 respectively.

Preferably, the MOS transistor circuit comprises a MOS transistor Q2, a capacitor C2; the corresponding end of the grid electrode of the MOS transistor Q2 is electrically connected with the other end of the resistor R12; the source of the MOS transistor Q2 is electrically connected with one end of a capacitor C2, and the drain of the MOS transistor Q2 is electrically connected with the other end of the capacitor C2; the drain of the MOS transistor Q2 is also electrically connected with the other end of the diode D6.

Preferably, the PWM control circuit further includes a resistor R15, a resistor R16, a resistor R18, a resistor R19, a capacitor C3, a resistor R17, a resistor R10, and a resistor R33; the first corresponding end of the PWM control chip is electrically connected with one end of a resistor R18, the other end of the resistor R18 is electrically connected with the other corresponding end of an optocoupler isolator U4A, the fourth corresponding end of the PWM control chip at the other end of a capacitor C4 and one end of a resistor R19, and the other end of the resistor R19 is grounded; the third corresponding end of the PWM control chip is electrically connected with one end of a capacitor C3 and one end of a resistor R17 respectively, the other end of the capacitor C3 is grounded, and the other end of the resistor R17 is electrically connected with one end of a resistor R10, one end of a resistor R33 and a source electrode of a MOS transistor Q2 respectively; the other end of the resistor R10 is electrically connected with the third corresponding end of the triode Q1 and the other end of the resistor R11 respectively; the other end of the resistor R33 is grounded; the other end of the resistor R16 is electrically connected with the other end of the diode D1 and one end of the diode D2 respectively.

By adopting the technical scheme of the utility model, the utility model has the following beneficial effects: the safety of the utility model is high, the design of the fuse plays a role in current limiting protection, and when the input current is greater than the rated current of the fuse, the fuse is disconnected to play a role in protection; the thermistor in the surge suppression protection circuit plays a role in surge suppression protection, and surge current can be generated at the moment of starting up; the voltage dependent resistor in the surge suppression protection circuit is a voltage limiting type protection device, and by utilizing the nonlinear characteristic of the voltage dependent resistor, when an overvoltage appears between two electrodes of the voltage dependent resistor, the voltage dependent resistor can clamp the voltage to a relatively fixed voltage value, so that the protection of a post-stage circuit is realized; the common-mode inductance circuit plays a role of EMI filtering and is used for inhibiting electromagnetic waves generated by the high-speed signal line from radiating and emitting outwards; utility model circuit power supply is difficult for receiving the interference, is equipped with the isolation protection circuit, and PWM control chip controls switching on and ending of MOS pipe through control PWM output circuit, can adjust the power size of output, can provide stabilizing voltage, and circuit protection nature is poor.

Drawings

FIG. 1 is a schematic diagram of the circuit of the present invention;

FIG. 2 is a schematic diagram of a protection circuit of the switching power supply of the present invention;

FIG. 3 is a schematic diagram of a PWM control circuit according to the present invention.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the utility model and are not to be construed as limiting the utility model.

In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", and the like, indicate orientations and positional relationships based on those shown in the drawings, and are used only for convenience of description and simplicity of description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be considered as limiting the present invention.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.

In the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally connected; 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 meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

In the present invention, a first feature "on" or "an over" a second feature unless expressly stated or limited otherwise

"under" may include the first and second features being in direct contact, and may also include the first and second features not being in direct contact, but being in contact with each other through additional features between them. Also, the first feature being "on," "above" and "over" the second feature includes the first feature being directly on and obliquely above the second feature, or merely indicating that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature includes the first feature being directly under and obliquely below the second feature, or simply meaning that the first feature is at a lesser elevation than the second feature.

Referring to fig. 1 to 3, the present invention provides a switching power supply control protection circuit including: the protection circuit comprises a switching power supply protection circuit 1 and a PWM control circuit 2 which is electrically connected with the corresponding end of the switching power supply protection circuit 1; the switching power supply protection circuit 1 comprises a current-limiting protection circuit 101, a surge suppression protection circuit 102, a common-mode inductance circuit 103, a rectifying whole bridge circuit 104, an electrolytic capacitor circuit 105 and an RCD absorption circuit 106; one end of the current-limiting protection circuit 101 is connected with one end of a mains supply, and the other end of the current-limiting protection circuit is electrically connected with the corresponding end of the surge suppression protection circuit 102; the other end of the commercial power is also electrically connected with the corresponding end of the surge suppression protection circuit 102; the corresponding end of the surge suppression protection circuit 102 is also electrically connected with the corresponding ends of the common-mode inductance circuit 103, the rectifier bridge circuit 104, the electrolytic capacitor circuit 105 and the RCD absorption circuit 106 in sequence; the PWM control circuit 2 comprises a PWM control chip 201, a PWM output circuit 203, a voltage stabilizing circuit 205, an optical coupler circuit 202 and a mos tube circuit 204; the corresponding end of the PWM control chip 201 is electrically connected with the optical coupler circuit 202, the voltage stabilizing circuit 205 and the PWM output circuit 203 respectively; the corresponding end of the PWM output circuit 203 is also electrically connected to the mos transistor circuit 204.

Referring to fig. 2, in the present embodiment, the fuse F1 plays a role of current limiting protection, and when the input current is greater than the rated current of the fuse F1, the fuse F1 is disconnected to play a role of protection; the current limiting protection circuit 101 includes a fuse F1, and one end of the fuse F1 is electrically connected to one end of the utility power. In the embodiment, the thermistor NTC1 plays a role in suppressing surge protection, and generates surge current at the moment of starting, so that a power type NTC thermistor is connected in series in the circuit, the surge current at the time of starting can be effectively suppressed, and after the effect of suppressing the circulating surge current is completed, the resistance value of the thermistor can be reduced under the continuous action of the current, so that the consumption is low, and the normal working current cannot be influenced; the voltage dependent resistor MOV1 in this embodiment is a voltage limited protection device; by utilizing the nonlinear characteristic of the voltage dependent resistor MOV1, when an overvoltage appears between two poles of the voltage dependent resistor MOV1, the voltage dependent resistor MOV1 can clamp the voltage to a relatively fixed voltage value, thereby realizing the protection of a rear-stage circuit; the surge suppression protection circuit 102 comprises a thermistor NTC1 and a piezoresistor MOV 1; one end of the thermistor NTC1 is electrically connected with the other end of the fuse F1, and the other end of the thermistor NTC1 is electrically connected with one end of the piezoresistor MOV1 respectively; the other end of the piezoresistor MOV1 is electrically connected with the other end of the commercial power.

The common mode inductor circuit 103 in this embodiment functions as an EMI filter for suppressing the electromagnetic wave generated by the high speed signal line from being radiated outward; the winding directions of the first coil and the second coil of the common-mode inductor LF1 are opposite, and the winding directions of the third coil and the fourth coil of the common-mode inductor LF2 are opposite, so that when normal current in the circuit flows through the common-mode inductor LF1 and the common-mode inductor LF2, the current generates opposite magnetic fields in the inductance coils wound in the same phase and cancels each other, and at this time, the normal signal current is mainly affected by the resistance of the coils (and a small amount of damping caused by leakage inductance); when common mode current flows through the coil, a homodromous magnetic field is generated in the coil due to the homodromous property of the common mode current, so that the inductive reactance of the coil is increased, the coil is high-impedance, and a strong damping effect is generated, so that the common mode current is attenuated, and the purpose of filtering is achieved; the function of the X capacitor in the circuit is mainly: the power supply overline circuit, the EMI filtering and the design of the capacitor CX1 are used for eliminating differential mode interference and ensuring that an electronic product finished product meets the EMC requirement; the common-mode inductance circuit 103 comprises a diode D1, a diode D2, a common-mode inductance LF1, a common-mode inductance LF2, a resistor R1, a resistor R1A, a resistor R2, a resistor R2A and a capacitor CX 1; the common-mode inductor LF1 comprises a first coil and a second coil which are wound on a magnetic core in parallel, and the winding directions of the first coil and the second coil are opposite; the common-mode inductor LF2 comprises a third coil and a fourth coil which are wound on a magnetic core in parallel, and the winding directions of the third coil and the fourth coil are opposite; one end of the diode D1 is electrically connected with the other end of the thermistor NTC1, one end of the varistor MOV1 and one end of the first coil respectively, and the other end of the diode D2 is electrically connected; the other end of the diode D2 is respectively and electrically connected with the other end of the piezoresistor MOV1 and the corresponding end of one end of the second coil; the other end of the first coil is electrically connected with one end of a resistor R1, one end of a resistor R1A, one end of a capacitor CX1 and one end of a third coil respectively; the other end of the second coil is respectively and electrically connected with one end of a resistor R2, one end of a resistor R2A, the other end of a capacitor CX1 and one end of a fourth coil; the other end of the resistor R1 is electrically connected with the other end of the resistor R2, the other end of the resistor R1A and the other end of the resistor R2A respectively; the other end of the third coil and the other end of the fourth coil are respectively and correspondingly electrically connected with the corresponding end of the rectifying whole-bridge circuit 104.

The rectifying bridge circuit 104 in this embodiment functions to rectify the ac power into dc power; the electrolytic capacitor C10 has the function that the rectifying bridge circuit 104 converts alternating current into pulsating direct current, and an electrolytic capacitor C10 with larger capacity is connected behind the rectifying circuit, so that the rectified pulsating direct current voltage is converted into relatively stable direct current voltage by utilizing the charging and discharging characteristics of the electrolytic capacitor C10; the electrolytic capacitor circuit 105 comprises a capacitor C10, one end of the capacitor C10 is electrically connected with the fourth corresponding end of the rectifying whole bridge circuit and grounded, and the other end of the capacitor C10 is electrically connected with the second corresponding end of the rectifying whole bridge circuit and the corresponding end of the RCD absorption circuit.

The RCD snubber circuit 106 in this embodiment is used to protect the switching tube; the RCD absorption circuit 106 comprises a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R7, a resistor R8, a resistor R9, a capacitor C1, a diode D6 and a diode D6; one end of the resistor R3 is electrically connected with a second corresponding end of the rectifying whole bridge circuit, the other end of the capacitor C10, one end of the resistor R4 and one end of the capacitor C1 respectively, and the other end of the resistor R3 is electrically connected with one end of the resistor R5, the other end of the resistor R4 and one end of the resistor R6 respectively; the other end of the resistor R5 is electrically connected with the other end of the resistor R6, one end of the diode D6, one end of the resistor R7, one end of the resistor R8 and one end of the resistor R9 respectively; the other end of the capacitor C1 is electrically connected with the other ends of the resistor R7, the resistor R8 and the resistor R9 respectively.

Referring to fig. 3, the PWM output circuit 203 in this embodiment includes a resistor R13A, a diode D3, a triode Q1, a resistor R11, and a resistor R12; one end of the resistor R13A is electrically connected with the corresponding end of the PWM control chip 201, and the other end of the resistor R13A is electrically connected with one end of the diode D3 and the first corresponding end of the triode Q1 respectively; a second corresponding end of the triode Q1 is electrically connected with the other end of the diode D3, one end of the resistor R11 and one end of the resistor R12 respectively; the first corresponding end of the triode Q1 is also electrically connected with the other end of the resistor R11; the other end of the resistor R12 is electrically connected with the corresponding end of the mos tube circuit 204; the model of the PWM control chip 201 is set as LD 5760; the voltage stabilizing circuit 205 comprises a diode D4, a resistor R14 and a capacitor C9; the sixth corresponding end of the PWM control chip is electrically connected with one end of a capacitor C9 and one end of a diode D4 respectively; the other end of the diode D4 is electrically connected with one end of the resistor R14; the optical coupling circuit 202 comprises an optical coupling isolator U4A and a capacitor C4; a second corresponding end of the PWM control chip 201 is electrically connected to the optocoupler isolator U4A and a corresponding end of the capacitor C4; the MOS tube circuit 204 comprises a MOS tube Q2 and a capacitor C2; the corresponding end of the grid electrode of the MOS transistor Q2 is electrically connected with the other end of the resistor R12; the source of the MOS transistor Q2 is electrically connected with one end of a capacitor C2, the drain of the MOS transistor Q2 is electrically connected with the other end of a capacitor C2, and the drain of the MOS transistor Q2 is also electrically connected with the other end of a diode D6; the PWM control circuit further comprises a resistor R15, a resistor R16, a resistor R18, a resistor R19, a capacitor C3, a resistor R17, a resistor R10 and a resistor R33; the first corresponding end of the PWM control chip is electrically connected with one end of a resistor R18, the other end of the resistor R18 is electrically connected with the other corresponding end of an optocoupler isolator U4A, the fourth corresponding end of the PWM control chip 201 at the other end of a capacitor C4 and one end of a resistor R19, and the other end of the resistor R19 is grounded; the third corresponding end of the PWM control chip 201 is electrically connected to one end of a capacitor C3 and one end of a resistor R17, respectively, the other end of the capacitor C3 is grounded, and the other end of the resistor R17 is electrically connected to one end of a resistor R10, one end of a resistor R33, and a source of a MOS transistor Q2, respectively; the other end of the resistor R10 is electrically connected with the third corresponding end of the triode Q1 and the other end of the resistor R11 respectively; the other end of the resistor R33 is grounded; the other end of the resistor R16 is electrically connected with the other end of the diode D1 and one end of the diode D2 respectively; one end of the resistor R13A is electrically connected to the fifth corresponding end of the PWM control chip 201.

The working principle of the PWM control circuit in this embodiment is as follows: a first pin of the PWM control circuit is an RT dual-function pin and is used for over-temperature closing/latching control, a second pin of the PWM control circuit is a feedback input pin, the PWM duty ratio is determined by the voltage level in the pin and a current sensing signal on a CS pin, a third pin of the PWM control circuit is a current sensing input pin, and the output power can be adjusted through a resistor 17, a resistor R33 and a resistor R10; the fourth pin of the PWM control circuit is a grounding pin, the fifth pin of the PWM control circuit is a PWM chip output control pin, the MOS transistor Q2 is controlled to be switched on and switched off by the PWM output circuit, the sixth pin of the PWM control circuit is VDD power supply IC power supply voltage, stable voltage is provided for the IC, the IC can work normally, and the eighth pin of the PWM control circuit is a high-voltage starting pin.

The above description is only a preferred embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications and equivalents of the technical solutions of the present invention, which are made by using the contents of the present specification and the accompanying drawings, or directly/indirectly applied to other related technical fields, are included in the scope of the present invention.

Claims (10)

1. A switching power supply control protection circuit, comprising: the PWM control circuit is electrically connected with the corresponding end of the switching power supply protection circuit; the switch power supply protection circuit comprises a current-limiting protection circuit, a surge suppression protection circuit, a common-mode inductor circuit, a rectifying whole bridge circuit, an electrolytic capacitor circuit and an RCD absorption circuit; one end of the current-limiting protection circuit is connected with one end of the commercial power, and the other end of the current-limiting protection circuit is electrically connected with the corresponding end of the surge suppression protection circuit; the other end of the commercial power is also electrically connected with the corresponding end of the surge suppression protection circuit; the corresponding end of the surge suppression protection circuit is also electrically connected with the corresponding ends of the common-mode inductance circuit, the rectifying and rectifying bridge circuit, the electrolytic capacitor circuit and the RCD absorption circuit in sequence; the PWM control circuit comprises a PWM control chip, a PWM output circuit, a voltage stabilizing circuit, an optical coupling circuit and a mos tube circuit; the corresponding end of the PWM control chip is electrically connected with the optical coupling circuit, the voltage stabilizing circuit and the PWM output circuit respectively; and the corresponding end of the PWM output circuit is electrically connected with the mos tube circuit.

2. The control protection circuit of claim 1, wherein the current limiting protection circuit comprises a fuse F1, one end of the fuse F1 is electrically connected to one end of the commercial power; the surge suppression protection circuit comprises a thermistor NTC1 and a piezoresistor MOV 1; one end of the thermistor NTC1 is electrically connected with the other end of the fuse F1, and the other end of the thermistor NTC1 is electrically connected with one end of the piezoresistor MOV1 respectively; and the other end of the piezoresistor MOV1 is electrically connected with the other end of the mains supply.

3. The switching power supply control protection circuit according to claim 2, wherein the common mode inductor circuit comprises a diode D1, a diode D2, a common mode inductor LF1, a common mode inductor LF2, a resistor R1, a resistor R1A, a resistor R2, a resistor R2A, and a capacitor CX 1;

the common-mode inductor LF1 comprises a first coil and a second coil which are wound on a magnetic core in parallel, and the winding directions of the first coil and the second coil are opposite; the common-mode inductor LF2 comprises a third coil and a fourth coil which are wound on a magnetic core in parallel, and the winding directions of the third coil and the fourth coil are opposite;

one end of the diode D1 is electrically connected with the other end of the thermistor NTC1, one end of the varistor MOV1 and one end of the first coil respectively, and the other end of the diode D2 is electrically connected; the other end of the diode D2 is respectively and electrically connected with the other end of the piezoresistor MOV1 and the corresponding end of one end of the second coil; the other end of the first coil is electrically connected with one end of a resistor R1, one end of a resistor R1A, one end of a capacitor CX1 and one end of a third coil respectively; the other end of the second coil is respectively and electrically connected with one end of a resistor R2, one end of a resistor R2A, the other end of a capacitor CX1 and one end of a fourth coil; the other end of the resistor R1 is electrically connected with the other end of the resistor R2, the other end of the resistor R1A and the other end of the resistor R2A respectively; the other end of the third coil and the other end of the fourth coil are respectively and correspondingly electrically connected with the corresponding end of the rectifying whole bridge circuit.

4. The control protection circuit of claim 3, wherein the electrolytic capacitor circuit comprises a capacitor C10, one end of the capacitor C10 is electrically connected to the fourth corresponding end of the rectifying bridge circuit and ground, and the other end is electrically connected to the second corresponding end of the rectifying bridge circuit and the corresponding end of the RCD absorption circuit.

5. The switching power supply control protection circuit according to claim 4, wherein the RCD absorption circuit comprises a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R7, a resistor R8, a resistor R9, a capacitor C1, a diode D6, and a diode D6; one end of the resistor R3 is electrically connected with a second corresponding end of the rectifying whole bridge circuit, the other end of the capacitor C10, one end of the resistor R4 and one end of the capacitor C1 respectively, and the other end of the resistor R3 is electrically connected with one end of the resistor R5, the other end of the resistor R4 and one end of the resistor R6 respectively; the other end of the resistor R5 is electrically connected with the other end of the resistor R6, one end of the diode D6, one end of the resistor R7, one end of the resistor R8 and one end of the resistor R9 respectively; the other end of the capacitor C1 is electrically connected with the other ends of the resistor R7, the resistor R8 and the resistor R9 respectively.

6. The switching power supply control protection circuit according to claim 1, wherein the PWM output circuit comprises a resistor R13A, a diode D3, a triode Q1, a resistor R11, and a resistor R12; one end of the resistor R13A is electrically connected with the corresponding end of the PWM control chip, and the other end of the resistor R13A is electrically connected with one end of the diode D3 and the first corresponding end of the triode Q1 respectively; a second corresponding end of the triode Q1 is electrically connected with the other end of the diode D3, one end of the resistor R11 and one end of the resistor R12 respectively; the first corresponding end of the triode Q1 is also electrically connected with the other end of the resistor R11; the other end of the resistor R12 is electrically connected with the corresponding end of the mos tube circuit; the model of the PWM control chip is set to be LD 5760.

7. The switching power supply control protection circuit according to claim 6, wherein the voltage regulation circuit comprises a diode D4, a resistor R14, a capacitor C9; the sixth corresponding end of the PWM control chip is electrically connected with one end of a capacitor C9 and one end of a diode D4 respectively; the other end of the diode D4 is electrically connected with one end of the resistor R14.

8. The switching power supply control protection circuit according to claim 7, wherein the optical coupling circuit comprises an optical coupling isolator U4A, a capacitor C4; and a second corresponding end of the PWM control chip is electrically connected with an optocoupler isolator U4A and a corresponding end of a capacitor C4 respectively.

9. The switching power supply control protection circuit according to claim 8, wherein the MOS transistor circuit comprises a MOS transistor Q2, a capacitor C2; the corresponding end of the grid electrode of the MOS transistor Q2 is electrically connected with the other end of the resistor R12; the source of the MOS transistor Q2 is electrically connected with one end of a capacitor C2, and the drain of the MOS transistor Q2 is electrically connected with the other end of the capacitor C2; the drain of the MOS transistor Q2 is also electrically connected with the other end of the diode D6.

10. The switching power supply control protection circuit according to claim 9, wherein the PWM control circuit further comprises a resistor R15, a resistor R16, a resistor R18, a resistor R19, a capacitor C3, a resistor R17, a resistor R10, a resistor R33; the first corresponding end of the PWM control chip is electrically connected with one end of a resistor R18, the other end of the resistor R18 is electrically connected with the other corresponding end of an optocoupler isolator U4A, the fourth corresponding end of the PWM control chip at the other end of a capacitor C4 and one end of a resistor R19, and the other end of the resistor R19 is grounded; the third corresponding end of the PWM control chip is electrically connected with one end of a capacitor C3 and one end of a resistor R17 respectively, the other end of the capacitor C3 is grounded, and the other end of the resistor R17 is electrically connected with one end of a resistor R10, one end of a resistor R33 and a source electrode of a MOS transistor Q2 respectively; the other end of the resistor R10 is electrically connected with the third corresponding end of the triode Q1 and the other end of the resistor R11 respectively; the other end of the resistor R33 is grounded; the other end of the resistor R16 is electrically connected with the other end of the diode D1 and one end of the diode D2 respectively.

Images