CN204205956U - Power supply device with over-power protection function - Google Patents

Abstract

A power supply device with an overpower protection function comprises a main converter, a voltage superposition circuit, a voltage detection circuit and a pulse width modulation controller. The voltage superposition circuit is electrically connected to the main converter; the voltage detection circuit is electrically connected to the main converter and the voltage superposition circuit; the pulse width modulation controller is electrically connected to the main converter and the voltage detection circuit. The main converter comprises an induction resistor. The voltage detection circuit detects an induction voltage of the induction resistor; when an output voltage of the power supply device is less than a preset output voltage, the voltage superposition circuit provides a superposition voltage to the voltage detection circuit, and then the voltage detection circuit transmits the induction voltage and the superposition voltage to the pulse width modulation controller.

Description

Power supply device with over-power protection function

technical field

The utility model relates to a power supply device, in particular to a power supply device with an overpower protection function.

Background technique

The power supply device provides power to the electronic device to drive the electronic device. If the power supply device transmits power through the USB interface, the electronic device will notify the power supply device of the required voltage, such as 5V or 20V.

The power supply device includes a transformer and a pulse width modulation controller. The transformer includes a primary winding, an auxiliary winding, and a secondary winding. When the electronic device informs the power supply device of the required voltage, the pulse width modulation controller changes the primary winding. The voltage of the side winding, the secondary side winding will sense the voltage of the primary side winding to generate a voltage to be sent to the electronic device; at the same time, the auxiliary winding will sense the voltage of the secondary side winding to generate a voltage to be sent to the pulse width modulation controller To supply power to the pulse width modulation controller.

Generally, when the USB interface is used to transmit power, the output current of the power supply device is limited to about 2 amperes; therefore, the output power of the power supply device is limited. In order to increase the output power of the power supply device under the condition of limited output current, the output voltage of the power supply device will be increased; for example, the output voltage of the power supply device is increased from 5 volts to 20 volts.

Generally speaking, the over-power protection function of the power supply device is fixed, such as designed with an output voltage of 5 volts or an output voltage of 20 volts; if the over-power protection function of the power supply device is designed with an output voltage of 20 volts, then when When the output voltage of the power supply device is 5 volts, the over-power protection function of the power supply device will not operate smoothly.

Please refer to FIG. 3, which is the over-power protection voltage waveform diagram of the over-power protection function of the power supply device of the related art when the output voltage is 20 volts; please refer to FIG. 4, which is the over-power protection of the power supply device of the related art Functional overpower protection voltage waveform diagram when the output voltage is 5 volts. Since the trigger level of the over-power protection voltage with an output voltage of 5 volts is the same as that of the over-power protection voltage with an output voltage of 20 volts, the output current at an output voltage of 5 volts must be greater than that at an output voltage of 20 volts output current to reach the trigger level of the over-power protection voltage; if the output current is larger, the power components in the power supply device will work at a state greater than the rated voltage or rated current, causing the power components to directly cause damage.

Utility model content

In order to improve the above-mentioned shortcomings of the prior art, the purpose of the utility model is to provide a power supply device with an over-power protection function.

In order to achieve the above purpose of the utility model, the power supply device with over-power protection function of the utility model includes a main converter; a voltage superposition circuit electrically connected to the main converter; a voltage detection circuit electrically connected to the main converter and the voltage superposition circuit; and a pulse width modulation controller electrically connected to the main converter and the voltage detection circuit. Wherein the main converter includes a sense resistor electrically connected to the voltage detection circuit, wherein the voltage detection circuit detects an sense voltage of the sense resistor; when an output voltage of the power supply device with over-power protection function is less than a When the output voltage is preset, the voltage superposition circuit provides a superimposed voltage to the voltage detection circuit, and then the voltage detection circuit sends the induced voltage and the superimposed voltage to the pulse width modulation controller; when the induced voltage is added to the When the superimposed voltage is greater than an overpower protection voltage, the pulse width modulation controller controls the main converter to stop working.

In the power supply device with overpower protection function, the voltage superposition circuit includes:

a superimposed voltage generation circuit electrically connected to the voltage detection circuit; and

a superimposed voltage control circuit, electrically connected to the superimposed voltage generating circuit and the transformer,

Wherein when the output voltage is lower than the preset output voltage, the superimposed voltage control circuit turns on the superimposed voltage generating circuit, so that the superimposed voltage generating circuit provides the superimposed voltage to the voltage detection circuit.

In the power supply device with over-power protection function, the main converter further includes:

A transformer electrically connected to the voltage superposition circuit, the PWM controller and the sensing resistor, wherein the transformer further includes:

a primary side winding;

a secondary winding; and

An auxiliary winding is electrically connected to the voltage superposition circuit.

In the power supply device with over-power protection function, the main converter further includes a transistor switch electrically connected to the primary side winding, the voltage detection circuit and the pulse width modulation controller.

In the power supply device with overpower protection function, the voltage superposition circuit further includes:

a first diode electrically connected to the auxiliary winding and the pulse width modulation controller; and

a first capacitor electrically connected to the first diode and the pulse width modulation controller,

Wherein the superposition voltage control circuit includes:

A first Zener diode is electrically connected to the first diode and the PWM controller.

The power supply device with overpower protection function is characterized in that the superimposed voltage control circuit further includes:

a first resistor electrically connected to the first Zener diode;

a second resistor electrically connected to the first resistor;

a first MOSFET electrically connected to the first resistor; and

A third resistor is electrically connected to the first diode, the first MOSFET and the PWM controller.

In the power supply device with overpower protection function, the superimposed voltage generating circuit includes:

a second MOSFET electrically connected to the first diode, the first MOSFET and the PWM controller;

a fourth resistor electrically connected to the second MOSFET and the voltage detection circuit; and

A second capacitor is electrically connected to the first diode, the second MOSFET and the PWM controller.

In the power supply device with over-power protection function, the voltage detection circuit includes:

a fifth resistor electrically connected to the transistor switch, the fourth resistor and the sensing resistor;

a sixth resistor electrically connected to the fourth resistor, the fifth resistor and the pulse width modulation controller; and

A third capacitor is electrically connected to the sixth resistor and the PWM controller.

The power supply device with over-power protection function further includes:

a primary side filter circuit electrically connected to the primary side winding;

a primary side rectifier circuit electrically connected to the primary side filter circuit;

a secondary side rectification circuit electrically connected to the secondary side winding; and

A secondary side filter circuit is electrically connected to the secondary side rectification circuit.

The power supply device with over-power protection function is applied to an AC power supply device and an electronic device, and the power supply device with over-power protection function further includes:

an electromagnetic interference filter electrically connected to the primary side rectifier circuit and the AC power supply device;

a universal serial bus interface electrically connected to the secondary side filter circuit and the electronic device;

a handshaking circuit electrically connected to the USB interface; and

A feedback circuit is electrically connected to the handshaking circuit, the secondary side filter circuit, the USB interface and the PWM controller.

The function of the utility model is that regardless of the output voltage of the power supply device, the over-power protection function of the power supply device can operate smoothly, and the cost of the circuit added to the power supply device is low, and the added circuit is located in the power supply device. primary side.

Description of drawings

Fig. 1 is the block diagram of the power supply device with overpower protection function of the present utility model;

Fig. 2 is a circuit diagram of an embodiment of the voltage superposition circuit and the voltage detection circuit of the present invention;

Fig. 3 shows the overpower protection function of the related art power supply device when the output voltage is 20 volts

The waveform diagram of the over-power protection voltage;

FIG. 4 shows the overpower protection function of the related art power supply device when the output voltage is 5 volts

The waveform diagram of the over-power protection voltage;

FIG. 5 is a waveform diagram of the overpower protection voltage when the output voltage is 5 volts with the overpower protection function of the power supply device with overpower protection function of the present invention.

Wherein reference signs:

Power supply unit with overpower protection function 10

AC power supply unit 20

Electronics 30

main converter 102

Voltage Superposition Circuit 104

Voltage detection circuit 106

Pulse Width Modulation Controller 108

Transformer 110

Primary side winding 112

Secondary side winding 114

Auxiliary winding 116

Transistor switch 118

Primary side filter circuit 120

Primary side rectification circuit 122

Secondary side rectification circuit 124

Secondary Side Filtering Circuit 126

EMI Filters 128

Universal Serial Bus Interface 130

handshake circuit 132

Feedback Circuit 134

First Diode 10402

The first capacitor 10404

First Zener Diode 10406

The first resistor 10408

Second resistor 10410

The first Mosfet 10412

Second Mosfet 10414

The third resistor 10416

Fourth resistor 10418

Second capacitor 10420

Superposition voltage generating circuit 10422

Superposition voltage control circuit 10424

Sensing resistor 10602

Fifth resistor 10604

Sixth resistor 10606

The third capacitor 10608

Detailed ways

Please refer to FIG. 1 , which is a block diagram of a power supply device with over-power protection function of the present invention; a power supply device 10 with over-power protection function is applied to an AC power supply device 20 and an electronic device 30 .

The power supply device 10 with overpower protection function includes a main converter 102, a voltage superposition circuit 104, a voltage detection circuit 106, a pulse width modulation controller 108, a primary side filter circuit 120, a primary side A rectifier circuit 122 , a secondary rectifier circuit 124 , a secondary filter circuit 126 , an EMI filter 128 , a USB interface 130 , a handshake circuit 132 and a feedback circuit 134 .

The main converter 102 includes a transformer 110, a transistor switch 118, and a sense resistor 10602; the transformer 110 includes a primary side winding 112, a secondary side winding 114, and an auxiliary winding 116, and the transistor switch 118 can be, for example, but not Defined as a Metal Oxide Semiconductor Field Effect Transistor.

The voltage superimposing circuit 104 is electrically connected to the main converter 102; the voltage detection circuit 106 is electrically connected to the main converter 102 and the voltage superimposing circuit 104; the pulse width modulation controller 108 is electrically connected to the The main converter 102 and the voltage detection circuit 106; the transformer 110 is electrically connected to the voltage superposition circuit 104, the pulse width modulation controller 108 and the sensing resistor 10602; the transistor switch 118 is electrically connected to the primary side The winding 112 , the voltage detection circuit 106 , the PWM controller 108 , and the sensing resistor 10602 ; the auxiliary winding 116 are electrically connected to the voltage superposition circuit 104 .

The primary side filter circuit 120 is electrically connected to the primary side winding 112; the primary side rectifier circuit 122 is electrically connected to the primary side filter circuit 120; the secondary side rectifier circuit 124 is electrically connected to the secondary side winding 114 the secondary side filter circuit 126 is electrically connected to the secondary side rectification circuit 124; the electromagnetic interference filter 128 is electrically connected to the primary side rectification circuit 122 and the AC power supply device 20;

The USB interface 130 is electrically connected to the secondary side filter circuit 126 and the electronic device 30; the handshake circuit 132 is electrically connected to the USB interface 130; the feedback circuit 134 is electrically connected to the The handshake circuit 132 , the secondary filter circuit 126 , the USB interface 130 , and the PWM controller 108 ; the sensing resistor 10602 are electrically connected to the voltage detection circuit 106 .

Please refer to FIG. 2 , which is a circuit diagram of an embodiment of the voltage superposition circuit and the voltage detection circuit of the present invention. The voltage superposition circuit 104 includes a superposition voltage generation circuit 10422, a superposition voltage control circuit 10424, a first diode 10402 and a first capacitor 10404; the superposition voltage generation circuit 10422 is electrically connected to the voltage detection circuit 106; The superimposed voltage control circuit 10424 is electrically connected to the superimposed voltage generating circuit 10422 and the auxiliary winding 116 of the transformer 110 .

When an output voltage of the power supply device 10 with overpower protection function is lower than a preset output voltage, the superimposed voltage control circuit 10424 is connected to the superimposed voltage generating circuit 10422, so that the superimposed voltage generating circuit 10422 provides a superimposed The voltage is supplied to the voltage detection circuit 106, the first diode 10402 and the first capacitor 10404 are used as filters.

The superimposed voltage control circuit 10424 includes a first zener diode 10406, a first resistor 10408, a second resistor 10410, a first metal oxide semiconductor field effect transistor 10412 and a third resistor 10416. The superimposed voltage generating circuit 10422 includes a second MOSFET 10414 , a fourth resistor 10418 and a second capacitor 10420 .

The first diode 10402 is electrically connected to the auxiliary winding 116 and the PWM controller 108; the first capacitor 10404 is electrically connected to the first diode 10402 and the PWM controller device 108; the first zener diode 10406 is electrically connected to the first diode 10402 and the pulse width modulation controller 108; the first resistor 10408 is electrically connected to the first zener diode 10406; The second resistor 10410 is electrically connected to the first resistor 10408; the first MOSFET 10412 is electrically connected to the first resistor 10408; the second MOSFET 10414 is electrically connected to The first diode 10402 , the first MOSFET 10412 and the PWM controller 108 .

The third resistor 10416 is electrically connected to the first diode 10402 , the first MOSFET 10412 , the second MOSFET 10414 and the PWM controller 108 ; the fourth resistor 10418 is electrically connected to the second MOSFET 10414 and the voltage detection circuit 106; the second capacitor 10420 is electrically connected to the first diode 10402, the second metal oxide The object semiconductor field effect transistor 10414 and the pulse width modulation controller 108. The second capacitor 10420 is used to supply power to the PWM controller 108 .

In other words, the anode of the first diode 10402 is connected to the auxiliary winding 116; the cathode of the first diode 10402 is connected to the PWM controller 108; one end of the first capacitor 10404 is connected to To the cathode of the first diode 10402 and the pulse width modulation controller 108, the other end of the first capacitor 10404 is grounded; the cathode of the first Zener diode 10406 is connected to the cathode of the first diode 10402 Cathode, one end of the first capacitor 10404 and the pulse width modulation controller 108; one end of the first resistor 10408 is connected to the anode of the first Zener diode 10406; one end of the second resistor 10410 is connected to the first The other end of a resistor 10408; the other end of the second resistor 10410 is grounded.

The gate of the first MOSFET 10412 is connected to the other end of the first resistor 10408 and one end of the second resistor 10410, and the source of the first MOSFET 10412 is grounded; The gate of the second MOSFET 10414 is connected to the drain of the first MOSFET 10412, and the drain of the second MOSFET 10414 is connected to the first two The cathode of the diode 10402 , one end of the first capacitor 10404 , the cathode of the first Zener diode 10406 and the PWM controller 108 .

One end of the third resistor 10416 is connected to the cathode of the first diode 10402, one end of the first capacitor 10404, the cathode of the first Zener diode 10406, and the drain of the second MOSFET 10414. pole and the pulse width modulation controller 108, the other end of the third resistor 10416 is connected to the drain of the first MOSFET 10412 and the gate of the second MOSFET 10414 pole; one end of the fourth resistor 10418 is connected to the source of the second MOSFET 10414, and the other end of the fourth resistor 10418 is connected to the voltage detection circuit 106; one end of the second capacitor 10420 is connected to To the cathode of the first diode 10402, one end of the first capacitor 10404, the cathode of the first Zener diode 10406, the drain of the second MOSFET 10414, the third resistor 10416 One end is connected to the PWM controller 108 , and the other end of the second capacitor 10420 is grounded.

The voltage detection circuit 106 includes a fifth resistor 10604 , a sixth resistor 10606 and a third capacitor 10608 .

The fifth resistor 10604 is electrically connected to the transistor switch 118, the fourth resistor 10418 and the sensing resistor 10602; the sixth resistor 10606 is electrically connected to the fourth resistor 10418, the fifth resistor 10604 and the pulse width Modulation controller 108 ; the third capacitor 10608 is electrically connected to the sixth resistor 10606 and the pulse width modulation controller 108 .

In other words, one end of the sensing resistor 10602 is connected to the transistor switch 118, and the other end of the sensing resistor 10602 is grounded; one end of the fifth resistor 10604 is connected to the transistor switch 118 and one end of the sensing resistor 10602, and the first end The other end of the fifth resistor 10604 is connected to the other end of the fourth resistor 10418; one end of the sixth resistor 10606 is connected to the other end of the fourth resistor 10418 and the other end of the fifth resistor 10604, and the sixth resistor 10606 The other end is connected to the pulse width modulation controller 108; one end of the third capacitor 10608 is connected to the pulse width modulation controller 108 and the other end of the sixth resistor 10606, and the other end of the third capacitor 10608 grounded.

Please refer to FIG. 1 and FIG. 2 at the same time, the electronic device 30 notifies the PWM controller 108 of a required voltage such as 5 volts or 20 volts; therefore, the pulse width modulation controller 108 controls the transistor switch 118 to change a primary side winding voltage of the primary side winding 112; wherein, the main converter 102 can be, for example but not limited to, a flyback Formula (flyback) converter, the pulse width modulation controller 108 controls the transistor switch 118 to change the primary side winding voltage of the primary side winding 112 is a prior art, for the sake of brevity, so it will not be repeated here. .

The voltage detection circuit 106 detects an induced voltage of the sensing resistor 10602; the voltage detection circuit 106 notifies the pulse width modulation controller 108 of the induced voltage; the pulse width modulation controller 108 with over-power protection function The over-power protection function is designed for the demand voltage of 20 volts; therefore, when the demand voltage is 20 volts, the over-power protection function can operate smoothly.

The following will describe how the over-power protection function can operate smoothly when the required voltage is 5 volts.

When the required voltage is 20 volts, the auxiliary winding voltage of the auxiliary winding 116 is, for example, 80 volts; when the required voltage is 5 volts, the auxiliary winding voltage of the auxiliary winding 116 is, for example, 20 volts; this is The prior art is for the sake of brevity, so it will not be repeated here.

A breakdown voltage of the first Zener diode 10406 is a preset voltage, greater than 20 volts but less than 80 volts, such as 40 volts; therefore when the auxiliary winding voltage is 80 volts or the required voltage is 20 volts, the The first MOSFET 10412 is turned on, the second MOSFET 10414 is not turned on, and the auxiliary winding voltage is not transmitted to the voltage detection circuit 106 .

The voltage detection circuit 106 transmits the induced voltage to the pulse width modulation controller 108; the pulse width modulation controller 108 determines whether the over-power protection function should be activated; this is the pulse wave with the over-power protection function The original over-power protection function of the width modulation controller 108 .

When the auxiliary winding voltage 20 volts of the auxiliary winding 116 is less than the preset voltage 40 volts, the required voltage is 5 volts, the first MOSFET 10412 will not be turned on, and the second metal oxide The semiconductor field effect transistor 10414 is turned on, and the auxiliary winding voltage is sent to the voltage detection circuit 106 .

In other words, the voltage superimposing circuit 104 provides the superimposed voltage, that is, the auxiliary winding voltage, to the voltage detection circuit 106, and then the voltage detection circuit 106 transmits the induced voltage and the superimposed voltage to the pulse width modulation controller 108; Therefore, the PWM controller 108 judges whether to activate the overvoltage or overpower protection function; that is, when the induced voltage plus the superimposed voltage is greater than an overpower protection voltage, the PWM control The controller 108 controls the main converter 102 to stop working.

When the required voltage is 5 volts, the pulse width modulation controller 108 receives the induced voltage and the superimposed voltage; the induced voltage received by the pulse width modulation controller 108 is raised by the superimposed voltage stacked to trigger the over-power protection function correctly, so the over-power protection function can operate smoothly.

That is, when the output voltage of the power supply device 10 with overpower protection function, eg 5 volts, is less than the preset output voltage, eg 10 volts, the voltage superimposing circuit 104 provides the superimposed voltage to the voltage detecting circuit 106 .

The superimposed voltage described in the above embodiment is the auxiliary winding voltage, but the utility model is not limited thereto; the superimposed voltage can also be from the primary side or secondary side of the power supply device 10 with overpower protection function A voltage source on the side, the voltage source is connected to the drain of the second MOSFET 10414, one end of the third resistor 10416 and one end of the second capacitor 10420, but the voltage source is not connected to the The cathode of the first diode 10402, one terminal of the first capacitor 10404 and the cathode of the first Zener diode 10406, ie, the circuit shown in FIG. 2 must be adjusted.

Please refer to Fig. 5, which is the overpower protection voltage waveform diagram of the overpower protection function of the power supply device with overpower protection function of the present utility model when the output voltage is 5 volts; the slope of the voltage shown in Fig. 5 and Fig. The slopes of the voltages shown in 4 are roughly the same, but the voltage shown in FIG. 5 is boosted by the superimposed voltage; when the output current of the power supply device 10 with overpower protection function increases, the third capacitor 10608 can be increased Therefore, compared with Figure 4, the same output voltage is 5 volts, and the compensation mechanism in Figure 5 makes it possible to reach the trigger level of the overpower protection voltage when the output voltage is 20 volts without requiring a larger output current The same over-power protection voltage trigger level; that is, even if the output voltage is 5 volts, the power supply device 10 with over-power protection function can have a correct and appropriate over-power protection mechanism to avoid the over-power protection Functional Power elements in the power supply device 10 work at a state greater than the rated voltage or rated current.

Wherein, although the above content is discussed for the voltage, the current can be obtained from the voltage, and the power is the product of the voltage and the current, so for the utility model, the over-power protection should have a similar meaning to the over-voltage protection.

The utility model has the advantages that regardless of the output voltage of the power supply device, the over-power protection function of the power supply device can operate smoothly, and the cost of the circuit added to the power supply device is low, and the added circuit is located in the power supply device. primary side.

This utility model can protect this transformer 110 and this electronic device 30; This protects the power supply device 10 with over-power protection function and the electronic device 30; that is, according to the voltage sent to the pulse width modulation controller 108 by the voltage detection circuit 106, the pulse width modulation control The device 108 controls the conduction state of the transistor switch 118 .

To sum up, it should be known that this utility model has industrial applicability, novelty and progress, and the structure of this utility model has never been seen in similar products and public use. It fully meets the requirements for patent application and is filed in accordance with the Patent Law.

Claims (10)

1. there is a power supply device for overpower protection function, it is characterized in that, comprise:

One main transducer;

One voltage overlaying circuit, is electrically connected to this main transducer;

One voltage detecting circuit, is electrically connected to this main transducer and this voltage overlaying circuit; And

One controller of pulse width modulation, is electrically connected to this main transducer and this voltage detecting circuit,

Wherein this main transducer comprises an inductive reactance, is electrically connected to this voltage detecting circuit;

Wherein this voltage detecting circuit detects one of this inductive reactance induced voltage; When the output voltage that this has the power supply device of overpower protection function is less than a pre-set output voltage, this voltage overlaying circuit provides a superimposed voltage to this voltage detecting circuit, and then this voltage detecting circuit transmits this induced voltage and this superimposed voltage to this controller of pulse width modulation; When this induced voltage adds that this superimposed voltage is greater than an overpower protection voltage, this controller of pulse width modulation controls this main transducer and quits work.

2. there is the power supply device of overpower protection function as claimed in claim 1, it is characterized in that,

This voltage overlaying circuit comprises:

One superimposed voltage produces circuit, is electrically connected to this voltage detecting circuit; And

One superimposed voltage control circuit, is electrically connected to this superimposed voltage and produces circuit and transformer,

Wherein when this output voltage is less than this pre-set output voltage, this this superimposed voltage of superimposed voltage control circuit conducting produces circuit, and making this superimposed voltage produce circuit provides this superimposed voltage to this voltage detecting circuit.

3. have the power supply device of overpower protection function as claimed in claim 1, it is characterized in that, this main transducer more comprises:

One transformer, is electrically connected to this voltage overlaying circuit, this controller of pulse width modulation and this inductive reactance,

Wherein this transformer more comprises:

One primary side winding;

One primary side winding; And

One auxiliary winding, is electrically connected to this voltage overlaying circuit.

4. have the power supply device of overpower protection function as claimed in claim 3, it is characterized in that, this main transducer more comprises a transistor switch, is electrically connected to this primary side winding, this voltage detecting circuit and this controller of pulse width modulation.

5. have the power supply device of overpower protection function as claimed in claim 4, it is characterized in that, this voltage overlaying circuit more comprises:

One first diode, is electrically connected to this auxiliary winding and this controller of pulse width modulation; And

One first electric capacity, is electrically connected to this first diode and this controller of pulse width modulation,

Wherein this superimposed voltage control circuit comprises:

One first Zener diode, is electrically connected to this first diode and this controller of pulse width modulation.

6. have the power supply device of overpower protection function as claimed in claim 5, it is characterized in that, this superimposed voltage control circuit more comprises:

One first resistance, is electrically connected to this first Zener diode;

One second resistance, is electrically connected to this first resistance;

One first mos field effect transistor, is electrically connected to this first resistance; And

One the 3rd resistance, is electrically connected to this first diode, this first mos field effect transistor and this controller of pulse width modulation.

7. have the power supply device of overpower protection function as claimed in claim 6, it is characterized in that, this superimposed voltage produces circuit and comprises:

One second mos field effect transistor, is electrically connected to this first diode, this first mos field effect transistor and this controller of pulse width modulation;

One the 4th resistance, is electrically connected to this second mos field effect transistor and this voltage detecting circuit; And

One second electric capacity, is electrically connected to this first diode, this second mos field effect transistor and this controller of pulse width modulation.

8. have the power supply device of overpower protection function as claimed in claim 7, it is characterized in that, this voltage detecting circuit comprises:

One the 5th resistance, is electrically connected to this transistor switch, the 4th resistance and this inductive reactance;

One the 6th resistance, is electrically connected to the 4th resistance, the 5th resistance and this controller of pulse width modulation; And

One the 3rd electric capacity, is electrically connected to the 6th resistance and this controller of pulse width modulation.

9. there is the power supply device of overpower protection function as claimed in claim 8, it is characterized in that, more comprise:

One primary side filter circuit, is electrically connected to this primary side winding;

One primary side rectification circuit, is electrically connected to this primary side filter circuit;

One secondary side rectifier circuit, is electrically connected to this primary side winding; And

One primary side filter circuit, is electrically connected to this secondary side rectifier circuit.

10. there is the power supply device of overpower protection function as claimed in claim 9; it is characterized in that; this power supply device with overpower protection function is applied to an AC power feeding mechanism and an electronic installation, and this power supply device with overpower protection function more comprises:

One Electromagnetic interference filter, is electrically connected to this primary side rectification circuit and this AC power feeding mechanism;

One USB (universal serial bus), is electrically connected to this primary side filter circuit and this electronic installation;

Circuit is held in one friendship, is electrically connected to this USB (universal serial bus); And

One feedback circuit, is electrically connected to this friendship and holds circuit, this primary side filter circuit, this USB (universal serial bus) and this controller of pulse width modulation.