CN202050366U - Forward structure switch power supply circuit - Google Patents

Abstract

The present utility model discloses a forward structure switch power supply circuit, and the circuit is used for converting alternating current input power supply into output power supply to supply external devices. The circuit comprises an input rectification filter unit, a forward switch unit, an output filter unit, a feedback sampling unit, a chip control unit, a reset unit, a drive unit and a chip power supply unit. The alternating current input power supply is subjected to rectification filtering by the input rectification filter unit, is subjected to forward switch by the forward switch unit and subjected to filtering by the output filter unit, and the output power supply supplying the external devices is generated. Feedback sampling is carried out by the feedback sampling unit, the drive unit is controlled by the chip control unit to drive the forward switch unit, reset control is carried out by the reset unit, and chip power signals of the chip control unit are power-supplied by the chip power supply unit. Thus, the forward switch power supply circuit can provide high precision output over-voltage protection designs, and has low standby power dissipation, high transition efficiency, low cost, low electromagnetic interference (EMI) radiation and simple design.

Description

Switching power supply circuit with forward structure

technical field

The utility model relates to a forward switching power supply circuit, in particular to a power supply circuit with a forward switching structure.

Background technique

After long-term excessive abuse of natural resources, human beings are facing the pressure of excessive energy consumption and serious environmental damage. Therefore, how to achieve energy conservation and emission reduction is imminent. In order to reduce the energy consumption of daily electrical equipment and electronic products, it is necessary to The power converter is optimized to achieve higher conversion efficiency and lower quiescent standby power consumption.

In the prior art, the forward structure is generally adopted in the small and medium power field because of its low cost and simple design. Generally, the conversion efficiency and standby power consumption of existing forward switching power supplies on the market are still not ideal, especially with the introduction of various stricter energy standards and safety regulations, the current forward switching power supplies have gradually become unsuitable. meet the needs.

Therefore, there is a need for a forward switching power supply conversion circuit that can meet new energy standards and safety regulations, so as to improve safety and practicality, and achieve various protection functions for power supplies of electronic products, thereby solving the above-mentioned problems.

Utility model content

The purpose of this utility model is to provide a forward switching power supply circuit, which is used to convert AC input power into output power and supply power to external devices, including input rectification filter unit, forward switch unit, output filter unit, feedback sampling unit, Chip control unit, reset unit, drive unit and chip power supply unit, wherein the input rectification and filtering unit converts the AC input power into the first signal after rectification and filtering, and generates the second signal and the divided voltage input signal, and the forward switch unit is connected to the first signal One signal, and the third, fourth, fifth and sixth signals are generated after the forward switch, the output filter unit is connected to the third signal, and after filtering, it generates an output power supply for external devices, and the feedback sampling unit is connected to the output power , and the seventh signal is generated after feedback sampling, the chip control unit is connected to the second, sixth, seventh signal and voltage-divided input signal, and controls and generates the eighth signal, one end of the reset unit is connected to the first signal, and the other end Connect the fourth signal for reset control, one end of the drive unit is connected to the eighth signal, the other end is connected to the ninth signal, and the ninth signal is further connected to and drives the forward switching unit, and the chip power supply unit is connected to the fifth signal , and generate a chip power signal that supplies power to the chip control unit.

In the described forward switching power supply circuit, the input rectifying and filtering unit includes a fuse, a first filter inductor, an electromagnetic interference (EMI) filter, a first voltage dividing resistor, a second voltage dividing resistor, A first voltage-dividing diode, a second voltage-dividing diode, a pre-stage filter capacitor, a second filter inductor, a rectifier bridge, and a post-stage filter capacitor, one end of the fuse is connected to the first AC terminal, and the The other end of the fuse and the second AC end are connected in parallel to a first side of the first filter inductor, and one end and the other end of the EMI filter are connected in parallel to a second side of the first filter inductor, An anode of the first voltage-dividing diode is connected to one end of the second side of the first filter inductor, and an anode of the second voltage-dividing diode is connected to the other end of the second side of the first filter inductor, so A negative pole of the first voltage dividing diode is connected to one end of the first voltage dividing resistor, a negative pole of the second voltage dividing diode is connected to one end of the second voltage dividing resistor, and the other end of the first voltage dividing resistor is One end and the other end of the second voltage dividing resistor are connected to the second signal, a first side of the second filter inductor is connected to a second side of the first filter inductor, and the rectifier bridge includes a first a diode, a second diode, a third diode and a fourth diode, a cathode of the first diode is connected to an anode of the second diode, and the A cathode of the third diode is connected to an anode of the fourth diode, a cathode of the first diode and a cathode of the third diode are connected in parallel to the second filter inductor On the second side, an anode of the first diode and an anode of the third diode are connected to the system ground, a cathode of the second diode, a cathode of the fourth diode A negative pole and one end of the post-stage filter capacitor are connected to the first signal, and the other end of the post-stage filter capacitor is connected to the system ground.

In the forward switching power supply circuit, the forward switching unit includes a forward transformer, a transistor and a sampling resistor, and the forward transformer is connected to the first signal, the third signal, the The fourth signal, the fifth signal, the system ground and the other system ground, and a first side of the forward transformer is connected to the first signal, the fourth signal, the fifth signal and the system ground, and a second side of the forward transformer is connected to the third signal and the other system ground, the transistor is a metal oxide semiconductor field effect transistor (MOSFET), and the A drain of the transistor is connected to the fourth signal, a gate of the transistor is connected to the ninth signal, a source of the transistor and one end of the sampling resistor are connected to the sixth signal, and the The other end of the sampling resistor is connected to the system ground.

In the forward switching power supply circuit, the output filter unit includes a first output rectifier diode, a second output rectifier diode, a filter capacitor and a filter inductor, and an anode of the first output rectifier diode Connect the third signal, a cathode of the first output rectifier diode and a cathode of the second output rectifier diode are connected to one end of the filter inductor, and an anode of the second output rectifier diode is connected to the filter One end of the capacitor, the other end of the filter capacitor is connected to the other system ground, and the other end of the filter inductor is connected to the output power supply.

In the forward switching power supply circuit, the feedback sampling unit includes an optical coupling component, a voltage stabilizing component, a feedback capacitor, a current limiting resistor, a first voltage dividing resistor, a feedback resistor and a first Two voltage divider resistors, the voltage stabilizing component is a three-terminal component with a positive pole, a negative pole and a third terminal, one end of the current limiting resistor and one end of the first voltage divider resistor are connected to the output power supply , the other end of the first voltage dividing resistor is connected to one end of the feedback resistor, one end of the second voltage dividing resistor and the third end of the voltage stabilizing component, and the other end of the second voltage dividing resistor is connected to The other system is grounded, the positive pole of the voltage stabilizing component is connected to the ground of the other system, the negative pole of the voltage stabilizing component is connected to the other end of the feedback capacitor, and the optical coupling component includes an optical coupling transistor and a light-emitting diode, a drain of the light-coupling transistor is connected to the seventh signal, a source of the light-coupling transistor is connected to the system ground, and an anode of the light-emitting diode is connected to the current limiting The other end of the resistor, and the negative pole of the LED is connected to the negative pole of the voltage stabilizing component.

In the forward switching power supply circuit, the chip control unit includes a control chip, a power filter resistor, a power filter capacitor, a first detection protection resistor, a second detection protection resistor, a detection protection capacitor, A sensing resistor and a sensing capacitor, the control chip is a control chip with a pulse width modulation (PWM) function, and the control chip has at least one ground terminal, a power supply terminal, a feedback terminal, and a sensing terminal , a detection protection terminal, a driving terminal and a high-voltage starting terminal, the ground terminal is connected to the system ground, the feedback terminal is connected to the seventh signal, the driving terminal is connected to the eighth signal, and the power supply The terminal is connected to the chip power signal, the high voltage starting terminal is connected to one end of the power filter resistor, the other end of the power filter resistor is connected to the second signal, and the detection protection terminal is connected to one end of the detection protection capacitor , one end of the first detection protection resistor and one end of the second detection protection resistor, the other end of the first detection protection resistor and the other end of the detection protection capacitor are connected to the system ground, the second The other end of the detection protection resistor is connected to the divided voltage input signal, the sensing end is connected to one end of the sensing resistor and one end of the sensing capacitor, and the other end of the sensing resistor is connected to the sixth signal , the other end of the sensing capacitor is connected to the system ground.

In the forward switching power supply circuit, the reset unit includes a Zener diode, a reset resistor, a reset capacitor and a reset diode, an anode of the Zener diode, one end of the reset resistor and the One end of the reset capacitor is connected to the first signal, one negative pole of the Zener diode, the other end of the reset resistor, and the other end of the reset capacitor are connected to a negative pole of the reset diode, and the reset diode An anode is connected to the fourth signal; or includes a reset resistor, a reset capacitor and a reset diode, one end of the reset resistor and one end of the reset capacitor are connected to the first signal, and the other end of the reset resistor and the other end of the reset capacitor is connected to a cathode of the reset diode, and an anode of the reset diode is connected to the fourth signal; or includes a reset diode and a reset inductor, and an anode of the reset diode is connected to the The system is grounded, a cathode of the reset diode is connected to one end of the reset inductor, and the other end of the reset inductor is connected to the first signal.

In the forward switching power supply circuit, the drive unit includes a drive resistor, one end of the drive resistor is connected to the eighth signal, and the other end of the drive resistor is connected to the ninth signal; or The drive unit includes a drive resistor, another drive resistor and a drive diode, one end of the drive resistor is connected to the eighth signal, and the other end of the drive resistor is connected to the ninth signal, and the drive diode A cathode is connected to the eighth signal, an anode of the driving diode is connected to one end of the other driving resistor, and the other end of the other driving resistor is connected to the ninth signal; or the driving unit includes a driving resistor, another drive resistor and a drive diode, one end of the drive resistor is connected to the eighth signal, and the other end of the drive resistor is connected to the ninth signal, and one end of the other drive resistor is connected to the For an eighth signal, the other end of the other drive resistor is connected to a cathode of the drive diode, and an anode of the drive diode is connected to the ninth signal; or the drive unit includes a drive resistor and a drive diode, One end of the driving resistor and a cathode of the driving diode are connected to the eighth signal, and the other end of the driving resistor and an anode of the driving diode are connected to the ninth signal.

In the forward switching power supply circuit, the chip power supply unit includes a first chip power supply capacitor, a second chip power supply capacitor, a chip power supply resistor and a chip power supply diode, and one end of the first chip power supply capacitor And one end of the second chip power supply capacitor is connected to the system ground, the other end of the first chip power supply capacitor and one end of the chip power supply resistor are connected to the chip power supply signal, and the other end of the chip power supply resistor is connected to The other end of the second chip power supply capacitor and a negative pole of the chip power supply diode, and an anode of the chip power supply diode connected to the fifth signal; or include a second chip power supply capacitor, a chip power supply resistor and A chip power supply diode, one end of the second chip power supply capacitor is connected to the system ground, the other end of the second chip power supply capacitor and a cathode of the chip power supply diode are connected to the chip power supply signal, and the chip power supply An anode of the diode is connected to one end of the chip power supply resistor, and the other end of the chip power supply resistor is connected to the fifth signal; or includes a second chip power supply capacitor and a chip power supply diode, and the second chip power supply capacitor One end of the second chip power supply capacitor is connected to the system ground, the other end of the second chip power supply capacitor and a cathode of the chip power supply diode are connected to the chip power supply signal, and an anode of the chip power supply diode is connected to the fifth signal; or It includes a second chip power supply capacitor, a chip power supply resistor and a chip power supply diode, one end of the second chip power supply capacitor is connected to the system ground, the other end of the second chip power supply capacitor and the chip power supply resistor One end is connected to the chip power supply signal, the other end of the chip power supply resistor is connected to a cathode of the chip power supply diode, and an anode of the chip power supply diode is connected to the fifth signal.

The forward switching power supply circuit of the utility model provides a high-precision output overvoltage protection design, and at the same time has the characteristics of low standby power consumption, high conversion efficiency, low cost, low EMI radiation, and simple design, especially can provide protection functions and meet various Safety standards.

Description of drawings

Fig. 1 is the schematic diagram of forward excitation switching power supply circuit in the utility model embodiment;

Fig. 2 is the schematic diagram of the input rectification filter unit in the utility model embodiment;

Fig. 3 is the schematic diagram of the forward switch unit in the utility model embodiment;

Fig. 4 is the schematic diagram of the output filtering unit in the utility model embodiment;

Fig. 5 is the schematic diagram of the feedback sampling unit in the utility model embodiment;

Fig. 6 is a schematic diagram of the chip control unit in the embodiment of the utility model;

Fig. 7 is a schematic diagram of a reset unit in an embodiment of the present invention;

Figure 8 is a schematic diagram of the drive unit in the embodiment of the present invention; and

Fig. 9 is a schematic diagram of the chip power supply unit in the embodiment of the present invention.

Detailed ways

In the following, the utility model will be described in more detail in the form of exemplary implementation, so that those skilled in the art can implement it after studying this description.

Referring to FIG. 1, FIG. 1 is a schematic diagram of the forward switching power supply circuit of the present invention. As shown in Figure 1, the forward switching power supply circuit 1 of the present utility model includes an input rectification and filtering unit 10, a forward switching unit 20, an output filtering unit 30, a feedback sampling unit 40, a chip control unit 50, a reset unit 60, and a drive unit 70 and the chip power supply unit 80 are used to convert the AC input power VAC into the output power VO, and then supply power to external devices (not shown in the figure).

The AC input power supply VAC has a first AC terminal VAC+ and a second AC terminal VAC-. The input rectification and filtering unit 10 converts the AC input power VAC into a first signal V1 after rectification and filtering, and generates a second signal V2 and a voltage-divided input signal VS. The flyback switch unit 20 is connected to the first signal V1 to control the flyback switch, and generates a third signal V3 , a fourth signal V4 , a fifth signal V5 and a sixth signal V6 . The output filtering unit 30 is connected to the third signal V3 for filtering, and generates a DC output power VO, and the DC output power VO supplies power to external devices.

The feedback sampling unit 40 is connected to the output power VO for feedback sampling, and generates the seventh signal V7, and the chip control unit 50 is connected to the second signal V2, the sixth signal V6, the seventh signal V7 and the divided input signal VS, and controls and An eighth signal V8 is generated. One end of the reset unit 60 is connected to the first signal V1, and the other end of the reset unit 60 is connected to the fourth signal V4 for reset control. One end of the driving unit 70 is connected to the eighth signal V8 , and the other end of the driving unit 70 is connected to the ninth signal V9 , and the ninth signal V9 is further connected to and drives the forward switching unit 20 . The chip power supply unit 80 is connected to the fifth signal V5 and generates a chip power supply signal VD that supplies power to the chip control unit.

In addition, one system ground is connected to the input rectifier filter unit 10 , the flyback switch unit 20 , the chip control unit 50 and the chip power supply unit 80 , and the other system ground is connected to the output filter unit 30 and the feedback sampling unit 40 .

With reference to Fig. 2, Fig. 2 is the schematic diagram of input rectification filter unit of the present invention, wherein input rectification filter unit 10 comprises fuse FUSE, the first filter inductance L1, electromagnetic interference (EMI) filter MOV, the first voltage divider resistor R1, the first Two voltage divider resistors R2, a first voltage divider diode DS1, a second voltage divider diode DS2, a pre-stage filter capacitor CX1, a second filter inductor L2, a rectifier bridge BD1 and a post-stage filter capacitor CX2.

One end of the fuse FUSE is connected to the first AC terminal VAC+, the other end of the fuse FUSE and the second AC terminal VAC- are connected in parallel to the first side of the first filter inductor L1, and one end and the other end of the EMI filter MOV are connected in parallel to the first filter inductor Second side of L1.

The anode of the first voltage-dividing diode DS1 is connected to one end of the second side of the first filter inductor L1, and the anode of the second voltage-dividing diode DS2 is connected to the other end of the second side of the first filter inductor L1, that is, the first voltage-dividing diode The anode of DS1 and the anode of the second voltage dividing diode DS2 are respectively connected across the two terminals of the EMI filter MOV. The cathode of the first divider diode DS1 is connected to one end of the first divider resistor R1, the cathode of the second divider diode DS2 is connected to one end of the second divider resistor R2, and the other end of the first divider resistor R1 and the second divider The other end of the piezoresistor R2 is connected to the second signal V2.

A first side of the second filter inductor L2 is connected to a second side of the first filter inductor L1.

The rectifier bridge BD1 includes a first diode DB1, a second diode DB2, a third diode DB3 and a fourth diode DB4, wherein the cathode of the first diode DB1 is connected to the anode of the second diode DB2 , the cathode of the third diode DB3 is connected to the anode of the fourth diode DB4, and the cathode of the first diode DB1 and the cathode of the third diode DB3 are connected in parallel to the second side of the second filter inductor L2, and The anode of the first diode DB1 and the anode of the third diode DB3 are connected to the system ground. The cathode of the second diode DB2, the cathode of the fourth diode DB4 and one end of the post-stage filter capacitor CX2 are connected to the first signal V1, and the other end of the post-stage filter capacitor CX2 is connected to the system ground.

Referring to FIG. 3, FIG. 3 is a schematic diagram of a forward switch unit of the present invention, wherein the forward switch unit 20 includes a forward transformer T, a transistor Q1 and a sampling resistor RS, wherein the forward transformer T is connected to the first signal V1, the third signal V3, the fourth signal V4, the fifth signal V5, the system ground and another system ground, and the first side of the forward transformer T is connected to the first signal V1, the fourth signal V4, the fifth signal V5 and the system ground, and the forward The second side of the excitation transformer T is connected to the third signal V3 and another system ground. The transistor Q1 is a Metal Oxide Semiconductor Field Effect Transistor (MOSFET), and the drain of the transistor Q1 is connected to the fourth signal V4, the gate of the transistor Q1 is connected to the ninth signal V9, the source of the transistor Q1 and one end of the sampling resistor RS are connected to the first Six signal V6, and the other end of the sampling resistor RS is connected to the system ground.

With reference to Fig. 4, Fig. 4 is the schematic diagram of output filter unit of the present utility model, wherein output filter unit 30 comprises first output rectifier diode D3X, second output rectifier diode D3Y, filter capacitor C3X and filter inductance L3X, and the first output rectifier diode The anode of D3X is connected to the third signal V3, the cathode of the first output rectifier diode D3X and the cathode of the second output rectifier diode D3Y are connected to one end of the filter inductor L3X, the anode of the second output rectifier diode D3Y is connected to one end of the filter capacitor C3X, and the filter capacitor The other end of C3X is connected to another system ground, and the other end of filter inductor L3X is connected to output power VO.

In addition, a π-type filter circuit or a common-mode filter circuit can be further added for different output ripple requirements.

Referring to FIG. 5, FIG. 5 is a schematic diagram of the feedback sampling unit of the present invention, wherein the feedback sampling unit 40 includes an optical coupling component TL, a voltage stabilizing component Z1, a feedback capacitor CF, a current limiting resistor R4X, a first voltage dividing resistor R41, a feedback The resistor R42 and the second voltage dividing resistor R43. The voltage stabilizing component Z1 is a three-terminal component, such as commercialized TL431, which has a positive pole, a negative pole and a third terminal. One end of the current limiting resistor R4X and one end of the first voltage dividing resistor R41 are connected to the output power VO, and the other end of the first voltage dividing resistor R41 is connected to one end of the feedback resistor R42, one end of the second voltage dividing resistor R43 and the voltage stabilizing component Z1 The third end, the other end of the second voltage dividing resistor R43 is connected to another system ground, the positive pole of the voltage stabilizing component Z1 is connected to the other system ground, and the negative pole of the voltage stabilizing component Z1 is connected to the other end of the feedback capacitor CF.

The light-coupling component TL includes a light-coupling transistor and a light-emitting diode, wherein the drain of the light-coupling transistor is connected to the seventh signal V7, the source of the light-coupling transistor is connected to the system ground, and the anode of the light-emitting diode is connected to the current limiting resistor R4X The other end of the LED, and the negative pole of the LED is connected to the negative pole of the voltage stabilizing component Z1.

Referring to FIG. 6, FIG. 6 is a schematic diagram of the chip control unit of the present invention, wherein the chip control unit 50 includes a control chip U1, a power filter resistor RV2, a power filter capacitor CV2, a first detection protection resistor RP1, a second detection protection resistor RP2, Detect the protection capacitor CP, the sensing resistor R5X and the sensing capacitor C5X.

The control chip U1 is a control chip with pulse width modulation (PWM) function, such as the commercialized OB5269B control chip, wherein the control chip U1 has at least a ground terminal GND, a power supply terminal VDD, a feedback terminal FB, a sensing terminal CS, and a detection protection terminal BO, drive terminal GATE and high voltage start terminal HV. The ground terminal GND is used to ground the chip, the power supply terminal VDD inputs the power supply required by the chip, the feedback terminal FB detects the secondary signal feedback, the sensing terminal CS can detect the primary current, the detection protection terminal BO is used for detecting signals, and the driving terminal GATE can control The switch of the power MOSFET, and the high-voltage startup terminal HV is used for the high-voltage startup of the chip.

The ground terminal GND is connected to the system ground, the feedback terminal FB is connected to the seventh signal V7, and the driving terminal GATE is connected to the eighth signal V8. The power terminal VDD is connected to the chip power signal VD, the high voltage start terminal HV is connected to one end of the power filter resistor RV2, and the other end of the power filter resistor RV2 is connected to the second signal V2. The detection and protection terminal BO is connected to one end of the detection and protection capacitor CP, one end of the first detection and protection resistor RP1, and one end of the second detection and protection resistor RP2, and the other end of the first detection and protection resistor RP1 and the other end of the detection and protection capacitor CP are connected to the system ground , and the other end of the second detection and protection resistor RP2 is connected to the divided voltage input signal VS. The sensing terminal CS is connected to one end of the sensing resistor R5X and one end of the sensing capacitor C5X, the other end of the sensing resistor R5X is connected to the sixth signal V6, and the other end of the sensing capacitor C5X is connected to the system ground.

Referring to FIG. 7, FIG. 7 is a schematic diagram of the reset unit of the present invention, wherein the reset unit 60 may include a zener diode TVS, a reset resistor R, a reset capacitor C and a reset diode D, wherein the anode of the zener diode TVS, the reset resistor R One end of the reset capacitor C and one end of the reset capacitor C are connected to the first signal V1, the negative pole of the Zener diode TVS, the other end of the reset resistor R and the other end of the reset capacitor C are connected to the negative pole of the reset diode D, and the positive pole of the reset diode D is connected to the fourth signal V4; or may include a reset resistor R, a reset capacitor C, and a reset diode D, wherein one end of the reset resistor R and one end of the reset capacitor C are connected to the first signal V1, and the other end of the reset resistor R and the other end of the reset capacitor C are connected to reset The cathode of the diode D, the anode of the reset diode D is connected to the fourth signal V4; or may include a reset diode D and a reset inductor L, wherein the anode of the reset diode D is grounded, the cathode of the reset diode D is connected to one end of the reset inductor L, and the reset inductor The other end of L is connected to the first signal V1.

Referring to FIG. 8, FIG. 8 is a schematic diagram of the drive unit of the present invention, wherein the drive unit 70 may include a drive resistor RG, wherein one end of the drive resistor RG is connected to the eighth signal V8, and the other end of the drive resistor RG is connected to the ninth signal V9; Or it may include a driving resistor RG, another driving resistor RG' and a driving diode DG, wherein one end of the driving resistor RG is connected to the eighth signal V8, and the other end of the driving resistor RG is connected to the ninth signal V9, and the negative pole of the driving diode DG is connected to the first signal V9. Eight signal V8, the anode of the driving diode DG is connected to one end of another driving resistor RG', and the other end of the other driving resistor RG' is connected to the ninth signal V9; or may include a driving resistor RG, another driving resistor RG' and a driving diode DG, wherein one end of the driving resistor RG is connected to the eighth signal V8, and the other end of the driving resistor RG is connected to the ninth signal V9, one end of the other driving resistor RG' is connected to the eighth signal V8, and the other end of the other driving resistor RG' is connected to the eighth signal V8. Connect the cathode of the drive diode DG, the anode of the drive diode DG is connected to the ninth signal V9; or may include a drive resistor RG and a drive diode DG, wherein one end of the drive resistor RG and the cathode of the drive diode DG are connected to the eighth signal V8, and the drive resistor The other end of RG and the anode of the driving diode DG are connected to the ninth signal V9.

Referring to FIG. 9, FIG. 9 is a schematic diagram of a chip power supply unit of the present invention, wherein the chip power supply unit 80 may include a first chip power supply capacitor C8X, a second chip power supply capacitor C8Y, a chip power supply resistor R8X, and a chip power supply diode D8X. One end of the power supply capacitor C8X and one end of the second chip power supply capacitor C8Y are connected to the system ground, the other end of the first chip power supply capacitor C8X and one end of the chip power supply resistor R8X are connected to the chip power signal VD, and the other end of the chip power supply resistor R8X is connected to the second The other end of the chip power supply capacitor C8Y and the cathode of the chip power supply diode D8X, and the anode of the chip power supply diode D8X is connected to the fifth signal V5; or may include a second chip power supply capacitor C8Y, a chip power supply resistor R8X and a chip power supply diode D8X, the second One end of the chip power supply capacitor C8Y is connected to the system ground, the other end of the second chip power supply capacitor C8Y and the negative pole of the chip power supply diode D8X are connected to the chip power supply signal VD, the positive pole of the chip power supply diode D8X is connected to one end of the chip power supply resistor R8X, and the chip power supply resistor The other end of R8X is connected to the fifth signal V5; or may include a second chip power supply capacitor C8Y and a chip power supply diode D8X, one end of the second chip power supply capacitor C8Y is connected to the system ground, the other end of the second chip power supply capacitor C8Y and the chip power supply diode The negative pole of D8X is connected to the chip power supply signal VD, and the positive pole of the chip power supply diode D8X is connected to the fifth signal V5; or may include a second chip power supply capacitor C8Y, a chip power supply resistor R8X and a chip power supply diode D8X, and one end of the second chip power supply capacitor C8Y is connected to The system is grounded, the other end of the second chip power supply capacitor C8Y and one end of the chip power supply resistor R8X are connected to the chip power supply signal VD, the other end of the chip power supply resistor R8X is connected to the negative pole of the chip power supply diode D8X, and the positive pole of the chip power supply diode D8X is connected to the fifth Signal V5.

The utility model is characterized in that, using the feedback structure formed by the optical coupling component TL and the voltage stabilizing component Z1 in the feedback sampling unit 40, the control chip U1 is provided to control the drive terminal GATE, and then the drive unit 70 is used to control the forward switching unit 20. duty cycle of transistor Q1.

Another feature of the utility model is that the detection and protection terminal BO of the control chip U1 can detect the voltage of the AC input power supply, and when the AC input power supply has a lower or higher voltage, it will generate an input undervoltage or overvoltage protection function to Stop driving the output driver GATE.

In addition, the high voltage enable terminal HV of the control chip U1 has two functions. One is the high-voltage starting function; the other is that when the AC input power is cut off at that time, after detecting the protection terminal BO, the HV tube of the high-voltage starting terminal can be turned on to the ground, so as to release the power stored in the front-stage filter capacitor CX1 in the input rectification filter unit 10 charge without using a discharge resistor, thus reducing standby power consumption.

Furthermore, the first voltage dividing resistor R1 and the second voltage dividing resistor R2 of the input rectification and filtering unit 10 combine with the power supply filter resistor RV2 of the chip control unit 50 to limit the current, prevent ESD or Surge from destroying the control chip U1, and improve the operation and durability. sex. It should be noted that the first voltage dividing resistor R1 and the second voltage dividing resistor R2 may be omitted as needed, that is, the first voltage dividing resistor R1 and the second voltage dividing resistor R2 are respectively short-circuited, and the CP of the chip control unit 50 Detecting the protection capacitor can also be omitted if necessary.

Modifications and changes from the embodiments shown and described will occur to those skilled in the art without departing from the scope of the invention as defined in the appended claims.

Claims (9)

1. the switching power circuit of a normal shock structure, in order to an alternating current input power supplying being converted to a direct current out-put supply, and power supply gives external device (ED), it is characterized in that the switching power circuit of this normal shock structure comprises:

One input rectifying filter unit converts described alternating current input power supplying to one first signal after rectification and filtering, and produces a secondary signal and a dividing potential drop input signal, and described alternating current input power supplying has one first interchange end and one second interchange end;

One normal shock switch element connects described first signal, to carry out positive energizing switch control and to produce one the 3rd signal, one the 4th signal, one the 5th signal and one the 6th signal;

One output filter unit connects described the 3rd signal carrying out filtering, and produces the described out-put supply that described external device (ED) is given in power supply;

One feedback sample unit connects described out-put supply carrying out feedback sample, and produces one the 7th signal;

One chip controls unit connects described secondary signal, described the 6th signal, described the 7th signal and described dividing potential drop input signal, and controls and produce one the 8th signal;

One reset unit has an end and the other end, and an end of described reset unit connects described first signal, and the other end of described reset unit connects described the 4th signal, and described reset unit is in order to the control that resets;

One driver element has an end and the other end, and an end of described driver element connects described the 8th signal, and the other end of described driver element connects one the 9th signal, and described the 9th signal further connects and drives described normal shock switch element; And

One chip power supply unit, connect described the 5th signal, and a chip power signal of chip controls unit is given in the generation power supply, and a system earth connects described input rectifying filter unit, described normal shock switch element, described chip controls unit and described chip power supply unit, and another system earth connects described output filter unit, described feedback sample unit and described chip controls unit.

2. the switching power circuit of normal shock structure according to claim 1 is characterized in that,

Described input rectifying filter unit comprises a fuse, one first filter inductance, one electromagnetic interference (EMI) filter, one first divider resistance, one second divider resistance, one first dividing potential drop diode, one second dividing potential drop diode, one prime filter capacitor, one second filter inductance, one rectifier bridge and a back grade filter capacitor, one end of described fuse connects described first and exchanges end, the other end of described fuse and described second exchanges one first side of holding described first filter inductance that is connected in parallel, be connected in parallel one second side of described first filter inductance of one end of described electromagnetic interface filter and the other end, an one anodal end that connects second side of described first filter inductance of the described first dividing potential drop diode, the one anodal other end that connects second side of described first filter inductance of the described second dividing potential drop diode, one negative pole of the described first dividing potential drop diode connects an end of described first divider resistance, one negative pole of the described second dividing potential drop diode connects an end of described second divider resistance, the other end of the other end of described first divider resistance and described second divider resistance connects described secondary signal, one first side of described second filter inductance connects one second side of described first filter inductance, described rectifier bridge comprises one first diode, one second diode, one the 3rd diode and one the 4th diode, one negative pole of described first diode connects a positive pole of described second diode, one negative pole of described the 3rd diode connects a positive pole of described the 4th diode, be connected in parallel second side of described second filter inductance of one negative pole of described first diode and a negative pole of described the 3rd diode, one positive pole anodal and described the 3rd diode of described first diode connects described system earth, one negative pole of described second diode, one end of one negative pole of described the 4th diode and described back level filter capacitor connects described first signal, and the other end of described back level filter capacitor connects described system earth.

3. the switching power circuit of normal shock structure according to claim 1 is characterized in that,

Described normal shock switch element comprises a normal shock transformer, one transistor and a sampling resistor, described normal shock transformer connects described first signal, described the 3rd signal, described the 4th signal, described the 5th signal, described system earth and described another system earth, and one first side of described normal shock transformer connects described first signal, described the 4th signal, described the 5th signal and described system earth, and one second side of described normal shock transformer connects described the 3rd signal and described another system earth, described transistor is a mos field effect transistor, and a described transistorized drain electrode connects described the 4th signal, a described transistorized grid connects described the 9th signal, one end of described transistorized one source pole and described sampling resistor connects described the 6th signal, and the other end of described sampling resistor connects described system earth.

4. the switching power circuit of normal shock structure according to claim 1 is characterized in that,

Described output filter unit comprises one first output rectifier diode, one second output rectifier diode, one filter capacitor and a filter inductance, and described the 3rd signal of an anodal connection of the described first output rectifier diode, one negative pole of one negative pole of the described first output rectifier diode and the described second output rectifier diode connects an end of described filter inductance, an one anodal end that connects described filter capacitor of the described second output rectifier diode, the other end of described filter capacitor connects described another system earth, and the other end of described filter inductance connects described out-put supply.

5. the switching power circuit of normal shock structure according to claim 1 is characterized in that,

Described feedback sample unit comprises that a smooth lotus root sets up part jointly, one stabipack, one feedback capacity, one current-limiting resistance, one first divider resistance, one feedback resistance and one second divider resistance, described stabipack is one or three end assemblies, has a positive pole, one negative pole and one the 3rd end, one end of described current-limiting resistance and an end of described first divider resistance connect described out-put supply, the other end of described first divider resistance connects an end of described feedback resistance, one end of described second divider resistance and the 3rd end of described stabipack, the other end of described second divider resistance connects described another system earth, the positive pole of described stabipack connects described another system earth, the negative pole of described stabipack connects the other end of described feedback capacity, described smooth lotus root is set up part jointly and comprises a smooth lotus root and close a transistor and a light-emitting diode, described smooth lotus root is closed a transistorized drain electrode and connects described the 7th signal, described smooth lotus root is closed transistorized one source pole and connects described system earth, the one anodal other end that connects described current-limiting resistance of described light-emitting diode, and the negative pole of described light-emitting diode connects the negative pole of described stabipack.

6. the switching power circuit of normal shock structure according to claim 1 is characterized in that,

Described chip controls unit comprises a control chip; one power filter resistance; one power filtering capacitor; one first detects protective resistance; one second detects protective resistance; one detects protection electric capacity; one sensing resistor and a sense capacitance; described control chip is the control chip with pulse-width modulation function; and described control chip has at least one earth terminal; one power end; one feedback end; one sense terminals; one detects the protection end; one drive end and a high voltage startup end; described earth terminal connects described system earth; described feedback end connects described the 7th signal; described drive end connects described the 8th signal; described power end connects described chip power signal; described high voltage startup end connects an end of described power filter resistance; the other end of described power filter resistance connects described secondary signal; described detection protection end connects an end of described detection protection electric capacity; described first end and described second that detects protective resistance detects an end of protective resistance; described first other end and the described detection that detects protective resistance protects the other end of electric capacity to connect described system earth; described second other end that detects protective resistance connects described dividing potential drop input signal; described sense terminals connects an end of described sensing resistor and an end of described sense capacitance; the other end of described sensing resistor connects described the 6th signal, and the other end of described sense capacitance connects described system earth.

7. the switching power circuit of normal shock structure according to claim 1 is characterized in that,

Described reset unit comprises a voltage stabilizing didoe, a reset resistor, a reset capacitance and a reset diode, one end of one positive pole of described voltage stabilizing didoe, described reset resistor and an end of described reset capacitance connect described first signal, the other end of one negative pole of described voltage stabilizing didoe, described reset resistor and the other end of described reset capacitance connect a negative pole of described reset diode, described the 4th signal of an anodal connection of described reset diode; Or comprise a reset resistor, a reset capacitance and a reset diode, one end of described reset resistor and an end of described reset capacitance connect described first signal, the other end of described reset resistor and the other end of described reset capacitance connect a negative pole of described reset diode, described the 4th signal of an anodal connection of described reset diode; Or comprise a reset diode and an inductance that resets, and one of described reset diode anodally connects described system earth, and a negative pole of described reset diode connects an end of the described inductance that resets, and the other end of the described inductance that resets connects described first signal.

8. the switching power circuit of normal shock structure according to claim 1 is characterized in that,

Described driver element comprises a driving resistor, and an end of described driving resistor connects described the 8th signal, and the other end of described driving resistor connects described the 9th signal; Or described driver element comprises that a driving resistor, another driving resistor and drive diode, one end of described driving resistor connects described the 8th signal, and the other end of described driving resistor connects described the 9th signal, one negative pole of described driving diode connects described the 8th signal, an one anodal end that connects described another driving resistor of described driving diode, the other end of described another driving resistor connects described the 9th signal; Or described driver element comprises that a driving resistor, another driving resistor and drive diode, one end of described driving resistor connects described the 8th signal, and the other end of described driving resistor connects described the 9th signal, one end of described another driving resistor connects described the 8th signal, the other end of described another driving resistor connects a negative pole of described driving diode, described the 9th signal of an anodal connection of described driving diode; Or described driver element comprises that a driving resistor and drives diode, one end of described driving resistor and a negative pole of described driving diode connect described the 8th signal, and described the 9th signal of an anodal connection of the other end of described driving resistor and described driving diode.

9. the switching power circuit of normal shock structure according to claim 1 is characterized in that,

Described chip power supply unit comprises one first chip power supply electric capacity, one second chip power supply electric capacity, an one chip power supply resistance and a chip power supply diode, one end of one end of the described first chip power supply electric capacity and the described second chip power supply electric capacity connects described system earth, one end of the other end of the described first chip power supply electric capacity and described chip power supply resistance connects described chip power signal, the other end of described chip power supply resistance connects the other end of the described second chip power supply electric capacity and a negative pole of described chip power supply diode, and described the 5th signal of an anodal connection of described chip power supply diode; Or comprise one second chip power supply electric capacity, a chip power supply resistance and a chip power supply diode, one end of the described second chip power supply electric capacity connects described system earth, one negative pole of the other end of the described second chip power supply electric capacity and described chip power supply diode connects described chip power signal, an one anodal end that connects described chip power supply resistance of described chip power supply diode, and the other end of described chip power supply resistance connects described the 5th signal; Or comprise one second a chip power supply electric capacity and a chip power supply diode, one end of the described second chip power supply electric capacity connects described system earth, one negative pole of the other end of the described second chip power supply electric capacity and described chip power supply diode connects described chip power signal, described the 5th signal of an anodal connection of described chip power supply diode; Or comprise one second chip power supply electric capacity, a chip power supply resistance and a chip power supply diode, one end of the described second chip power supply electric capacity connects described system earth, one end of the other end of the described second chip power supply electric capacity and described chip power supply resistance connects described chip power signal, the other end of described chip power supply resistance connects a negative pole of described chip power supply diode, and described the 5th signal of an anodal connection of described chip power supply diode.

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