CN211239326U - Anti-surge protection circuit with double fuse - Google Patents

Abstract

The utility model discloses an anti-surge protection circuit with double fuses in a switching power supply, including an input filter unit, including fuses F1, F2, varistor MOV1, thermistor NTC1, and common mode inductor LF1. The fuse F1 is connected to the L end of the AC power input, and the fuse F2 is connected to the N end of the AC power input; the varistor MOV1 is connected to the tail end of the fuse F1 and the tail end of the fuse F2; the beneficial effect of the utility model is that the power adapter provided by the utility model adopts a double fuse structure, thereby greatly improving the safety and practicality of the power adapter. The setting of two fuses, one large and one small, can not only improve the product's ability to resist lightning strikes, but also play a good protective role for subsequent circuits, and has great advantages in safety, practicality, and cost.

Description

Anti-surge protection circuit with double fuse

technical field

The utility model relates to the technical field of power supplies, in particular to an anti-surge protection circuit, in particular to an anti-surge protection circuit with double fuses.

Background technique

The current power adapter generally includes an input filter unit, a rectification and smoothing unit, a PWM pulse width modulation control unit, a rectification filter unit and a feedback control unit, and an anti-lightning circuit should be set in the input filter unit.

Most of the current products' anti-lightning circuits use a single fuse. Because the current flowing through the lightning circuit is very large, the selected fuses have very high fusing current specifications. Although this solves the problem of anti-lightning, it appears in the subsequent circuit. When abnormal, it cannot play a protective role, and the product has poor anti-surge ability consistency.

Utility model content

The purpose of this utility model is to solve the problem that most of the anti-lightning circuits in the prior art use a single fuse. Since the current flowing through the lightning circuit is very large, the selected fuses have very high fusing current specifications. Although this solves the problem of anti-lightning However, it cannot play a protective role in the event of an abnormality in the subsequent circuit, and the product has poor consistency in anti-surge capability. An anti-surge protection circuit with dual fuses is proposed to meet people's needs for this type of product.

In order to achieve the purpose, the utility model adopts the following technical solutions: design and manufacture an anti-surge protection circuit with double fuses, and the anti-surge protection circuit includes:

An input filter unit, including fuses F1, F2, varistor MOV1, thermistor NTC1, and common mode inductor LF1, which are used to suppress the interference signal in the input AC power supply and output to the rectifier and smoothing unit; the The fuse F1 is connected to the AC power input L terminal, the fuse F2 is connected to the AC power input N terminal; the varistor MOV1 is connected to the tail end of the fuse F1 and the tail end of the fuse F2;

The rectifier smoothing unit includes a rectifier bridge BD1 and a leakage inductance absorption circuit composed of smoothing capacitors C1, C2, capacitors C3, resistors R5, R6, R7 and diode D5 connected to the input end and the output end of the rectifier bridge. The AC voltage is converted into a smooth DC voltage and then output to the PWM pulse width modulation control unit; the resistor R5 is connected in parallel with the capacitor C3 and the cathode of the diode D5;

PWM pulse width modulation control unit, including PWM controller IC1, diode D6, resistors R3, R4, R8, R9, R10, R11, R12, R13, R16, RS1, RS2, capacitors C6, C6A, C13; the PWM The fifth pin of the controller U1 is connected to the starting resistors R3, R4, R13 to provide the IC with the starting voltage. The positive terminal of the transformer auxiliary coil T1B passes through R8, D6, R12, and the capacitors C6 and C6A are connected to the PWM controller IC1. The third pin, the auxiliary coil The negative terminal of T1B is directly grounded, PIN6 of IC1 drives Q1 through R9, PIN4 is the overcurrent detection input,

Rectification and filtering unit, including transformers T1C, D8, filter capacitor C8, and filter inductor LF2; it is used to transform, rectify and filter the pulsating DC voltage and then output it to the load; the secondary winding of T1C is rectified by D8, and filtered by C8 to provide The DC voltage is applied to the load; the resistor R15 is connected in series with the capacitor C11 and then connected to both ends of D8;

A feedback control unit, which is composed of an optocoupler IC2, a voltage reference IC3, a capacitor C12, and resistors R21, R20, R19, R14, R17, and R18; used to collect changes in the output voltage signal of the rectifier and filter unit, The resistor R19 and the resistor R18 determine the voltage reference value, and the resistor R14 is connected to the output voltage V+ terminal to determine the current flowing through the IC2A.

The fuse F1 has a melting current of 6.3A.

The fuse F12 fuses a current of 2A.

In the feedback control unit, the optocoupler IC2A is connected in series with IC3, the optocoupler IC2B is connected to the second pin of IC1, the optocoupler IC2A is connected to the negative end of the rectifier diode D8 through the resistor R14, and the other end of IC3 is grounded; the control end of IC3 is connected to the resistor R19 Connect to one end of the filter inductor LF2A.

The IC1 uses AP8268 model and compatible models.

The beneficial effects of the utility model are: the power adapter provided by the utility model adopts a double fuse structure, thereby greatly improving the safety and practicability of the power adapter. It improves the lightning resistance of the product, and plays a very good protective role for the subsequent circuit. It has huge advantages in safety, practicability and cost.

Description of drawings

FIG. 1 is a schematic diagram of the arrangement of two large and small fuses involved in the anti-surge protection circuit with double fuses of the present invention.

Detailed ways

The technical solutions of the present utility model will be further described below with reference to the accompanying drawings and through the best embodiments.

As shown in Figure 1, the anti-surge protection circuit with double fuses includes an input filter unit, including fuses F1, F2, varistor MOV1, thermistor NTC1, and common mode inductance LF1. The interference signal in the AC power supply is suppressed and then output to the rectification and smoothing unit; the fuse F1 is connected to the AC power input L end, the fuse F2 is connected to the AC power input N end; the varistor MOV1 is connected to the tail end of the fuse F1 and The tail end of fuse F2;

The rectifier smoothing unit includes a rectifier bridge BD1 and a leakage inductance absorption circuit composed of smoothing capacitors C1, C2, capacitors C3, resistors R5, R6, R7 and diode D5 connected to the input end and the output end of the rectifier bridge. The AC voltage is converted into a smooth DC voltage and then output to the PWM pulse width modulation control unit; the resistor R5 is connected in parallel with the capacitor C3 and the cathode of the diode D5;

PWM pulse width modulation control unit, including PWM controller IC1, diode D6, resistors R3, R4, R8, R9, R10, R11, R12, R13, R16, RS1, RS2, capacitors C6, C6A, C13; the PWM The fifth pin of the controller U1 is connected to the starting resistors R3, R4, R13 to provide the IC with the starting voltage. The positive terminal of the transformer auxiliary coil T1B passes through R8, D6, R12, and the capacitors C6 and C6A are connected to the PWM controller IC1. The third pin, the auxiliary coil The negative terminal of T1B is directly grounded, PIN6 of IC1 drives Q1 through R9, and PIN4 is the overcurrent detection input;

Rectification and filtering unit, including transformers T1C, D8, filter capacitor C8, and filter inductor LF2; it is used to transform, rectify and filter the pulsating DC voltage and output it to the load; the secondary winding of T1C is rectified by D8, and filtered by C8 to provide The DC voltage is applied to the load; the resistor R15 is connected in series with the capacitor C11 and then connected to both ends of D8;

A feedback control unit, which is composed of an optocoupler IC2, a voltage reference IC3, a capacitor C12, and resistors R21, R20, R19, R14, R17, and R18; used to collect changes in the output voltage signal of the rectifier and filter unit, The resistor R19 and the resistor R18 determine the voltage reference value, and the resistor R14 is connected to the output voltage V+ terminal to determine the current flowing through the IC2A.

The fuse F1 has a melting current of 6.3A.

Fuse F12 blows current 2A.

Feedback control unit, optocoupler IC2A and IC3 are connected in series, optocoupler IC2B is connected to IC1 pin 2, optocoupler IC2A is connected to the negative end of rectifier diode D8 through resistor R14, and the other end of IC3 is grounded; IC3 control end is connected through resistor R19. One end of filter inductor LF2A.

IC3 generally uses TL431.

The IC1 uses the AP8268 model, and can also choose the BM1P107FJ. This model is an 8-pin IC, and its function is very similar to the AP8268 model. There are many ICs similar to the AP8268 model, so I won't list them here.

The above contents are only the preferred embodiments of the present invention. For those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation and application scope, and the contents of this description should not be construed as Limitations of the present invention.

Claims (5)

1. An anti-surge protection circuit with a dual fuse, the protection circuit comprising:

the input filtering unit comprises fuses F1 and F2, a voltage dependent resistor MOV1, a thermistor NTC1 and a common mode inductor LF1, and is used for inhibiting interference signals in an input alternating current power supply and then outputting the interference signals to the rectification smoothing unit; the fuse F1 is connected to the L end of the AC power input, and the fuse F2 is connected to the N end of the AC power input; the piezoresistor MOV1 is connected with the tail end of the fuse F1 and the tail end of the fuse F2;

the rectifying smoothing unit comprises a rectifier bridge BD1, a leakage inductance absorption circuit which is connected with the output end of the rectifier bridge through the input end of the smoothing capacitor C1 and C2, the capacitor C3, the resistor R5, the resistor R6, the resistor R7 and the diode D5, and is used for converting input alternating current voltage into smooth direct current voltage and outputting the smooth direct current voltage to the PWM control unit; the resistor R5 is connected with the cathode of the diode D5 in parallel with the capacitor C3;

the PWM control unit comprises a PWM controller IC1, a diode D6, a resistor R3, a resistor R4, a resistor R8, a resistor R9, a resistor R10, a resistor R11, a resistor R12, a resistor R13, a resistor R16, a resistor RS1, a resistor RS2, capacitors C6, C6A and C13; the 5 th PIN of the PWM controller U1 is connected with starting resistors R3, R4 and R13 to provide starting voltage for the IC, the positive end of an auxiliary coil T1B of the transformer is connected with the 3 rd PIN of the PWM controller IC1 through R8, D6, R12, capacitors C6 and C6A, the negative end of the auxiliary coil T1B is directly grounded, a PIN6 of the IC1 drives Q1 through R9, and PIN4 is used as overcurrent detection input,

the rectifying and filtering unit comprises transformers T1C, D8, a filtering capacitor C8 and a filtering inductor LF 2; the direct current voltage rectifier is used for converting the pulsating direct current voltage, rectifying and filtering the pulsating direct current voltage and outputting the rectified direct current voltage to a load; the secondary winding of the T1C is rectified by the D8, and the DC voltage is provided for a load after the filtering of the C8; the resistor R15 is connected with the capacitor C11 in series and then connected to two ends of the D8 in parallel;

the feedback control unit is composed of an optical coupler IC2, a voltage reference IC3, a capacitor C12 and resistors R21, R20, R19, R14, R17 and R18; the resistor R19 and the resistor R18 are used for acquiring the change of an output voltage signal of the rectifying and filtering unit, determining a voltage reference value, and the resistor R14 is connected with an output voltage V + end and determining the current flowing through the IC 2A.

2. The anti-surge protection circuit with double fuse according to claim 1, wherein said fuse F1 blows current 6.3A.

3. The anti-surge protection circuit with double fuse according to claim 1, wherein said fuse F12 blows current 2A.

4. The anti-surge protection circuit with the double fuse according to claim 1, wherein the feedback control unit, the optical coupler IC2A is connected in series with the IC3, the optical coupler IC2B is connected to the 2 nd pin of the IC1, the optical coupler IC2a is connected to the negative terminal of the rectifier diode D8 through a resistor R14, and the other terminal of the IC3 is grounded; the control terminal of the IC3 is connected to one terminal of the filter inductor LF2A through a resistor R19.

5. The anti-surge protection circuit with double fuses of claim 1, wherein the IC1 is an AP8268 type.

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