TWM496290U - Power supply apparatus with over power protection function - Google Patents

Abstract

A power supply apparatus includes 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 includes a sensing resistor. The voltage detection circuit detects a sensing voltage of the sensing resistor. The voltage superposition circuit supplies a superposition voltage to the voltage detection circuit when an output voltage of the power supply apparatus is less than a predetermined output voltage, and then the voltage detection circuit sends the sensing voltage and the superposition voltage to the pulse width modulation controller.

Description

Power supply device with over-power protection

The present invention relates to a power supply device, and more particularly to a power supply device having an overpower protection function.

The power supply device supplies power to the electronic device to drive the electronic device. If the power supply unit uses a universal serial bus interface to transmit power, the electronic device notifies the power supply device of the required voltage (eg, 5 volts or 20 volts).

The power supply device comprises a transformer and a pulse width modulation controller, and the transformer comprises a primary side winding, an auxiliary winding and a secondary side winding; when the electronic device notifies the voltage required by the power supply device, the pulse width modulation controller changes the primary The voltage of the side winding, the secondary side winding senses the voltage of the primary side winding to generate a voltage for transmission to the electronic device; meanwhile, the auxiliary winding senses the voltage of the secondary side winding to generate a voltage for transmission to the pulse width modulation controller Power is supplied to the pulse width modulation controller.

In general, when the power is transmitted using the universal serial bus interface, the output current of the power supply device is limited to about 2 amps; therefore, the output power of the power supply device is limited. In order to increase the output power of the power supply device in the case of the 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.

In general, the overpower protection function of the power supply unit is fixed (designed at an output voltage of 5 volts or an output voltage of 20 volts); if the overpower protection function of the power supply unit is designed with an output voltage of 20 volts, then When the output voltage of the power supply unit is 5 volts, the overpower protection function of the power supply unit will not operate smoothly.

Please refer to FIG. 3 , which is a waveform diagram of an over-power protection voltage of an over-power protection function of a related art power supply device at an output voltage of 20 volts; please refer to FIG. 4 , which is a related art power supply device. The over-power protection voltage waveform of the power protection function at an output voltage of 5 volts. Since the trigger level of the over-power protection voltage with an output voltage of 5 volts is the same as the trigger level 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 the output voltage of 20 volts. The output current is used 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 operate at a state greater than the rated voltage or rated current, causing the power component to directly cause damage.

In order to improve the above disadvantages of the prior art, the purpose of the present invention is to provide a power supply device having an overpower protection function.

In order to achieve the above object of the present invention, the power supply device with overpower protection function of the present invention comprises a main converter; a voltage superposition circuit electrically connected to the main converter; and a voltage detection circuit electrically connected to The main converter and the voltage superimposing circuit; and a pulse width modulation controller electrically connected to the main converter and the voltage detecting circuit. The main converter includes a sensing resistor electrically connected to the voltage detecting circuit. The voltage detecting circuit detects an induced voltage of the sensing resistor; When the output voltage of the power supply device having the overpower protection function is less than a predetermined output voltage, the voltage superimposing circuit provides a superimposed voltage to the voltage detecting circuit, and then the voltage detecting circuit transmits the induced voltage and the Superimposing a voltage to the pulse width modulation controller; when the induced voltage plus the superimposed voltage is greater than an overpower protection voltage, the pulse width modulation controller controls the main converter to stop operating.

The effect of this creation is that the over-power protection function of the power supply device can operate smoothly regardless of the output voltage of the power supply device, and the added circuit of the power supply device is low in cost and the added circuit is located once in the power supply device. side.

10‧‧‧Power supply unit with over-power protection

20‧‧‧AC power supply unit

30‧‧‧Electronic devices

102‧‧‧Main converter

104‧‧‧Voltage superposition circuit

106‧‧‧Voltage detection circuit

108‧‧‧ Pulse width modulation controller

110‧‧‧Transformers

112‧‧‧Primary winding

114‧‧‧Secondary side winding

116‧‧‧Auxiliary winding

118‧‧‧Transistor Switch

120‧‧‧Primary side filter circuit

122‧‧‧Primary side rectifier circuit

124‧‧‧Secondary side rectifier circuit

126‧‧‧Secondary side filter circuit

128‧‧‧Electromagnetic interference filter

130‧‧‧Common Serial Bus Interface

132‧‧‧Cross-grip circuit

134‧‧‧Return circuit

10402‧‧‧First Diode

10404‧‧‧First capacitor

10406‧‧‧First Zener diode

10408‧‧‧First resistance

10410‧‧‧second resistance

10412‧‧‧First Metal Oxide Semiconductor Field Effect Transistor

10414‧‧‧Second metal oxide semiconductor field effect transistor

10416‧‧‧ Third resistor

10418‧‧‧fourth resistor

10420‧‧‧second capacitor

10422‧‧‧Overlay voltage generation circuit

10424‧‧‧Overlay voltage control circuit

10602‧‧‧Induction resistance

10604‧‧‧ fifth resistor

10606‧‧‧6th resistor

10608‧‧‧ third capacitor

FIG. 1 is a block diagram of a power supply device with an overpower protection function according to the present invention.

FIG. 2 is a circuit diagram of an embodiment of a voltage superimposing circuit and a voltage detecting circuit of the present invention.

3 is a waveform diagram of an over-power protection voltage of an over-power protection function of a power supply device of the related art at an output voltage of 20 volts.

4 is a waveform diagram of an over-power protection voltage of an over-power protection function of a power supply device of the related art at an output voltage of 5 volts.

FIG. 5 is a waveform diagram of the over-power protection voltage of the over-power protection function of the power supply device with over-power protection function at an output voltage of 5 volts.

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

The power supply device 10 with over power 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, and a primary The side rectification circuit 122, the primary-stage side rectification circuit 124, the primary-stage side filter circuit 126, an electromagnetic interference filter 128, a universal serial bus 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 primary side winding 114 and an auxiliary winding 116. The transistor switch 118 can be, for example but not limited to, a metal oxide semiconductor field effect transistor.

The voltage superimposing circuit 104 is electrically connected to the main converter 102; the voltage detecting 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 main converter 102 and the voltage detecting circuit 106; the transformer 110 is electrically connected to the voltage superimposing circuit 104, the pulse width modulation controller 108 and the sensing resistor 10602; the transistor switch 118 is electrically connected to The primary winding 112, the voltage detecting circuit 106, the pulse width modulation controller 108, and the sensing resistor 10602; the auxiliary winding 116 is electrically connected to the voltage superimposing 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 rectifier circuit 124; the electromagnetic interference filter 128 is electrically connected to the primary side rectifier circuit 122 and the AC power supply device 20.

The universal serial bus 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 universal serial bus interface 130; the feedback circuit 134 is electrically The sensing resistors 10602 are electrically connected to the voltage detecting circuit 106. The sensing circuit 10 is electrically connected to the voltage detecting circuit 106. The sensing circuit is electrically connected to the voltage detecting circuit 106.

Please refer to FIG. 2 , which is a circuit diagram of an embodiment of the voltage superimposing circuit and the voltage detecting circuit of the present invention. The voltage superimposing circuit 104 includes a superimposed voltage generating circuit 10422, a superimposed voltage control circuit 10424, a first diode 10402 and a first capacitor 10404. The superimposed voltage generating circuit 10422 is electrically connected to the voltage detecting 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 the output voltage of one of the power supply devices 10 having the overpower protection function is less than a predetermined output voltage, the superimposed voltage control circuit 10424 turns on the superimposed voltage generating circuit 10422, so that the superimposed voltage generating circuit 10422 provides a superimposed voltage to The voltage detecting 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 metal oxide semiconductor field effect transistor 10414, a fourth resistor 10418 and a second capacitor 10420.

The first diode 10402 is electrically connected to the auxiliary winding 116 and the pulse width modulation controller 108; the first capacitor 10404 is electrically connected to the first diode 10402 and The pulse width modulation controller 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 metal oxide semiconductor field effect transistor 10412 is electrically connected to the first resistor 10408; the second The metal oxide semiconductor field effect transistor 10414 is electrically connected to the first diode 10402, the first metal oxide semiconductor field effect transistor 10412, and the pulse width modulation controller 108.

The third resistor 10416 is electrically connected to the first diode 10402, the first metal oxide semiconductor field effect transistor 10412, the second metal oxide semiconductor field effect transistor 10414, and the pulse width modulation control The fourth resistor 10418 is electrically connected to the second metal oxide semiconductor field effect transistor 10414 and the voltage detecting circuit 106; the second capacitor 10420 is electrically connected to the first diode 10402, A second metal oxide semiconductor field effect transistor 10414 and the pulse width modulation controller 108. The second capacitor 10420 is for supplying power to the pulse width modulation 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 pulse width modulation controller 108; one end of the first capacitor 10404 is connected 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 first diode 10402 a cathode, an 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 other end of the first resistor 10408; the other of the second resistor 10410 One end is grounded.

The gate of the first metal oxide semiconductor field effect transistor 10412 is connected to the other end of the first resistor 10408 and one end of the second resistor 10410. The source of the first metal oxide semiconductor field effect transistor 10412 is grounded. The gate of the second metal oxide semiconductor field effect transistor 10414 is connected to the drain of the first metal oxide semiconductor field effect transistor 10412, and the drain of the second metal oxide semiconductor field effect transistor 10414 is connected The cathode of the first diode 10402, one end of the first capacitor 10404, the cathode of the first Zener diode 10406, and the pulse width modulation 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 second metal oxide semiconductor field effect transistor. a drain of 10414 and the pulse width modulation controller 108, the other end of the third resistor 10416 is connected to the drain of the first metal oxide semiconductor field effect transistor 10412 and the second metal oxide semiconductor field effect a gate of the transistor 10414; one end of the fourth resistor 10418 is connected to the source of the second metal oxide semiconductor field effect transistor 10414, and the other end of the fourth resistor 10418 is connected to the voltage detecting circuit 106; One end of the second capacitor 10420 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 second metal oxide semiconductor field effect transistor 10414. The drain, the one end of the third resistor 10416 and the pulse width modulation controller 108, the other end of the second capacitor 10420 is grounded.

The voltage detecting 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 wave. The width modulation controller 108 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. 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, 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 third capacitor 10608 is another One end is grounded.

Please also refer to Figure 1 and Figure 2. The electronic device 30 notifies the pulse width modulation controller 108 of a required voltage (for example, 5 volts or 20 volts) through the universal serial bus interface 130, the handshake circuit 132, and the feedback circuit 134; 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 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 as a conventional technique, which is a concise factor and will not be described herein.

The voltage detecting circuit 106 detects an induced voltage of the sensing resistor 10602; the voltage detecting circuit 106 notifies the pulse width modulation controller 108 of the induced voltage; and the power supply device 10 having an overpower protection function (the Pulse width modulation controller 108 The over-power protection function is designed for the required voltage of 20 volts; therefore, when the required 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, one of the auxiliary windings 116 has an auxiliary winding voltage of, 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 a well-known technique and is a concise factor, so it will not be repeated here.

A breakdown voltage of the first Zener diode 10406 is a predetermined voltage greater than 20 volts but less than 80 volts, for example 40 volts; therefore, when the auxiliary winding voltage is 80 volts (the required voltage is 20 volts) The first MOSFET field transistor 10412 is turned on, the second MOSFET field 10414 is not turned on, and the auxiliary winding voltage is not transmitted to the voltage detecting circuit 106.

The voltage detecting circuit 106 transmits the induced voltage to the pulse width modulation controller 108; the pulse width modulation controller 108 determines whether the power protection function is activated; this is the power source with the overpower protection function. The original device 10 (the pulse width modulation controller 108) has an overpower protection function.

The first metal oxide semiconductor field effect when the auxiliary winding voltage (20 volts) of the main converter 102 (the auxiliary winding 116) is less than the predetermined voltage (40 volts) (the required voltage is 5 volts) The transistor 10412 is not turned on, the second MOSFET 1041 is turned on, and the auxiliary winding voltage is transmitted to the voltage detecting circuit 106.

In other words, the voltage superimposing circuit 104 supplies the superimposed voltage (ie, the auxiliary winding voltage) to the voltage detecting circuit 106, and then the voltage detecting circuit 106 transmits the induced voltage and the superimposed voltage to the pulse width modulation. The variable controller 108; thereby, the pulse width modulation controller 108 determines whether the overvoltage (power) protection function is activated; that is, when the induced voltage plus the superimposed voltage is greater than an overpower protection voltage, The pulse width modulation controller 108 controls the main converter 102 to stop operating.

When the required voltage is 5 volts, the pulse width modulation controller 108 receives the induced voltage and the superimposed voltage (not just the induced voltage); the pulse width modulation controller 108 receives The induced voltage is padded (higher by the superimposed voltage) to properly trigger the over-power protection function, so the over-power protection function can operate smoothly.

That is, when the output voltage (for example, 5 volts) of the power supply device 10 having the overpower protection function is less than the predetermined output voltage (for example, 10 volts), the voltage superimposing circuit 104 supplies the superimposed voltage to the voltage Detector. Circuit 106.

The superimposed voltage described in the above embodiment is the auxiliary winding voltage, but the creation is not limited thereto; the superimposed voltage may also be the primary side or the secondary of the power supply device 10 having the over-power protection function. a voltage source connected to the drain of the second metal oxide semiconductor field effect transistor 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 cathode of the first diode 10402, one end of the first capacitor 10404, and the cathode of the first Zener diode 10406 (that is, the circuit shown in FIG. 2 must be adjusted).

Please refer to FIG. 5, which is an over-power protection voltage wave of an over-power protection function of the power supply device with over-power protection function at an output voltage of 5 volts. The slope of the voltage shown in FIG. 5 is substantially the same as the slope of the voltage shown in FIG. 4, but the voltage shown in FIG. 5 is raised by the superimposed voltage; when the power supply device 10 having the overpower protection function is provided When the output current is increased, the voltage of the third capacitor 10608 can be increased; therefore, compared with FIG. 4, the output voltage is also 5 volts, and the compensation mechanism of FIG. 5 makes it possible to achieve and output without requiring a larger output current. The over-power protection voltage at a voltage of 20 volts triggers the same over-power protection voltage trigger level; that is, even if the output voltage is 5 volts, the power supply device 10 having the over-power protection function can have the correct and appropriate The power protection mechanism is used to prevent the power components in the power supply device 10 having the overpower protection function from operating at a state greater than a rated voltage or a rated current.

Among them, 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. Therefore, for the present creation, the over-power protection should have a similar meaning to the over-voltage protection.

The advantage of this creation is that regardless of the output voltage of the power supply device (for example, 5 volts or 20 volts as described above), the overpower protection function of the power supply device can operate smoothly, and the circuit of the power supply device increases the cost of the circuit. And the added circuit is located on the primary side of the power supply.

The present invention protects the transformer 110 and the electronic device 30; when the voltage detecting circuit 106 detects that the voltage (current) has reached the overcurrent protection point, the pulse width modulation controller 108 turns off the transistor switch. 118, thereby protecting the power supply device 10 having the over-power protection function and the electronic device 30; that is, according to the voltage transmitted by the voltage detecting circuit 106 to the pulse width modulation controller 108, the pulse wave The width modulation controller 108 controls the conduction state of the transistor switch 118.

In summary, when Zhiben's creation has industrial applicability, novelty and progressiveness, and the structure of this creation has not been seen in similar products and public use, it fully complies with the requirements of new patent applications and applies for patent law.

10‧‧‧Power supply unit with over-power protection

20‧‧‧AC power supply unit

30‧‧‧Electronic devices

102‧‧‧Main converter

104‧‧‧Voltage superposition circuit

106‧‧‧Voltage detection circuit

108‧‧‧ Pulse width modulation controller

110‧‧‧Transformers

112‧‧‧Primary winding

114‧‧‧Secondary side winding

116‧‧‧Auxiliary winding

118‧‧‧Transistor Switch

120‧‧‧Primary side filter circuit

122‧‧‧Primary side rectifier circuit

124‧‧‧Secondary side rectifier circuit

126‧‧‧Secondary side filter circuit

128‧‧‧Electromagnetic interference filter

130‧‧‧Common Serial Bus Interface

132‧‧‧Cross-grip circuit

134‧‧‧Return circuit

10602‧‧‧Induction resistance

Claims (10)

A power supply device with an over-power protection function 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 And a pulse width modulation controller electrically connected to the main converter and the voltage detecting circuit, wherein the main converter includes a sensing resistor electrically connected to the voltage detecting circuit; wherein the voltage is The detecting circuit detects an induced voltage of the sensing resistor; when the output voltage of the power supply device having the overpower protection function is less than a predetermined output voltage, the voltage superimposing circuit provides a superimposed voltage to the voltage detecting circuit Then, the voltage detecting circuit transmits the induced voltage and the superimposed voltage to the pulse width modulation controller; and when the induced voltage plus the superimposed voltage is greater than an overpower protection voltage, the pulse width modulation controller Control the main converter to stop working. The power supply device with an over-power protection function as described in claim 1, wherein the voltage superimposing circuit comprises: a superimposed voltage generating circuit electrically connected to the voltage detecting circuit; and a superimposed voltage control circuit, Electrically connected to the superimposed voltage generating circuit, wherein when the output voltage is less than the predetermined 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 detecting Circuit. The power supply device with an over-power protection function as described in claim 2, wherein the main converter further comprises: a transformer electrically connected to the voltage superimposing circuit, the pulse width modulation controller, and the The induction resistor, wherein the transformer further comprises: a primary side winding; a primary side winding; and an auxiliary winding electrically connected to the voltage superposition circuit. The power supply device with an over-power protection function according to claim 3, wherein the main converter further includes a transistor switch electrically connected to the primary side winding, the voltage detecting circuit, and the pulse wave. Width modulation controller. The power supply device with an over-power protection function according to claim 4, wherein the voltage superimposing circuit further comprises: a first diode, electrically connected to the auxiliary winding, and the pulse width modulation control And a first capacitor electrically connected to the first diode and the pulse width modulation controller, wherein the superimposed voltage control circuit comprises: a first Zener diode electrically connected to the The first diode and the pulse width modulation controller. The power supply device with an over-power protection function according to claim 5, wherein the superimposed voltage control circuit further comprises: a first resistor electrically connected to the first Zener diode; and a second a resistor electrically connected to the first resistor; a first metal oxide semiconductor field effect transistor electrically connected to the first resistor And a third resistor electrically connected to the first diode, the first metal oxide semiconductor field effect transistor, and the pulse width modulation controller. The power supply device with an over power protection function according to claim 6, wherein the superimposed voltage generating circuit comprises: a second metal oxide semiconductor field effect transistor electrically connected to the first diode The first metal oxide semiconductor field effect transistor and the pulse width modulation controller; a fourth resistor electrically connected to the second metal oxide semiconductor field effect transistor and the voltage detecting circuit; A second capacitor is electrically connected to the first diode, the second MOSFET, and the pulse width modulation controller. The power supply device with an over-power protection function according to claim 7, wherein the voltage detecting circuit comprises: 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 electrically connected to the sixth resistor and the pulse width modulation Controller. The power supply device with over power protection function as described in claim 8 further includes: a primary side filter circuit electrically connected to the primary side winding; and a primary side rectifier circuit electrically connected to the primary a side filter circuit; a primary-stage side rectifier circuit electrically connected to the secondary side winding; and a primary-stage side filter circuit electrically connected to the secondary-side rectifier circuit. The power supply device with over-power protection function as described in claim 9 is applied to an AC power supply device and an electronic device, and the power supply device with over-power protection function further comprises: an electromagnetic interference filter The device is 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; and a handshake circuit electrically connected to The universal serial bus interface; and a feedback circuit electrically connected to the handshake circuit, the secondary side filter circuit, the universal serial bus interface, and the pulse width modulation controller.