Input under-voltage protection and auxiliary light-off circuit and power adapter

Abstract

The invention relates to the technical field of power supplies, in particular to an input under-voltage protection and auxiliary lamp turn-off circuit and a power adapter. Comprising a rectifier diode, a second voltage dividing module, a voltage stabilizing diode, a first MOS tube, a second MOS tube and a first voltage dividing module, the input end of the rectifier diode, the input end of the first voltage dividing module and the grid electrode of the second MOS tube are all connected with a power adapter, and the rectifier diode, the second voltage dividing module and the voltage stabilizing diode are sequentially connected. The positive electrode of the voltage stabilizing diode is connected with the grid electrode of the first MOS tube. The drain electrode of the first MOS tube and the grid electrode of the second MOS tube are connected with the output end of the first voltage dividing module. When the input voltage is lower than the preset voltage, the voltage is divided by the second voltage dividing module and loaded to the voltage stabilizing diode so as to break down the voltage stabilizing diode, the first MOS tube is not conducted, the second MOS tube is conducted, the VCC pin of the PWM control chip is pulled down by the second MOS tube and then stops working, and the primary end voltage of the transformer cannot be transmitted to the secondary end. Therefore, under-voltage protection and turn-off of the power indicating lamp are realized.

Description

Technical Field

[0001] The invention relates to the technical field of power supply, in particular to an input undervoltage protection and auxiliary light-off circuit and a power adapter. Background Art

[0002] At present, the power adapters or chargers on the market generally do not have the functions of input undervoltage protection and quick power-off light-off. Such products have certain defects. On the one hand, when the power supply is designed for 200-240VAC rated input working conditions, if there is no input undervoltage protection function, when the power supply is applied to low voltage input scenarios (such as 120V), the power supply will heat up seriously or even be damaged; on the other hand, when the power is cut off, the electric energy stored in the electrolytic capacitor on the primary side of the transformer will continue to be transmitted to its secondary side, making it difficult for the power indicator light to be extinguished in time, which is easy to cause error signals.

[0003] Therefore, it is very important for those skilled in the art to design an input undervoltage protection and auxiliary light-off circuit and a power adapter. Summary of the invention

[0004] The technical problem to be solved by the embodiments of the present invention is to provide an input undervoltage protection and auxiliary light-off circuit and a power adapter to solve the problem in the prior art that the power supply is easily damaged by heat and easily provides an erroneous signal.

[0005] The present invention discloses an input undervoltage protection and auxiliary light-off circuit, which is applied to a power adapter. The scheme is that the circuit comprises: a rectifier diode, a second voltage divider module, a voltage regulator diode, a first MOS tube, a second MOS tube and the first voltage divider module, wherein the input end of the rectifier diode is connected to the mains input end of the power adapter, the output end of the rectifier diode is connected to the input end of the second voltage divider module, the output end of the second voltage divider module is connected to the negative electrode of the voltage regulator diode, the positive electrode of the voltage regulator diode is connected to the grid of the first MOS tube, the drain of the first MOS tube and the grid of the second MOS tube are both connected to the output end of the first voltage divider module, the input end of the first voltage divider module is connected to the primary end of the transformer of the power adapter, the source of the first MOS tube and the source of the second MOS tube are both grounded, and the drain of the second MOS tube is connected to the PWM control chip of the power adapter.

[0006] Optionally, the first voltage divider module includes a first resistor, a second resistor and a third resistor connected in series, and the drain of the first MOS tube and the drain of the second MOS tube are both connected between the second resistor and the third resistor.

[0007] Optionally, the second voltage-dividing module includes a fourth resistor, a fifth resistor and a sixth resistor connected in series, and the cathode of the voltage-stabilizing diode is connected between the fifth resistor and the sixth resistor.

[0008] In order to solve the problems existing in the prior art, the present invention also provides a power adapter, whose solution is that it includes the input undervoltage protection and auxiliary light-off circuit as described above, and also includes a mains input end, a transformer, a PWM control chip, a charging control chip and an indicator light module. The input undervoltage protection and auxiliary light-off circuit are respectively connected to the voltage input end and the PWM control chip, the control end of the PWM control chip is connected to the primary end of the transformer, the primary end of the transformer is connected to the mains input end, the secondary end of the transformer is connected to the charging control chip, and the control end of the voltage control chip is connected to the indicator light module.

[0009] Optionally, a rectifier and filter module is further included, wherein a voltage input end of the rectifier and filter module is connected to the mains input end, and a voltage output end of the rectifier and filter module is connected to the primary end of the transformer.

[0010] Optionally, a first energy storage capacitor is provided between the rectification and filtering module and the primary end of the transformer, and an output end of the first energy storage capacitor is connected to an input end of the first voltage divider module.

[0011] Optionally, a second energy storage capacitor is further provided between the secondary end of the transformer and the charging control chip, and an output end of the second energy storage capacitor is connected to a voltage input pin of the charging control chip.

[0012] Optionally, a third MOS tube is arranged between the charging control chip and the indicator light module, the gate of the third MOS tube is connected to the control end of the charging control chip, the source of the third MOS tube is grounded, and the drain of the third MOS tube is connected to the indicator light module.

[0013] Optionally, it also includes an output interface, an inductor and a buck MOS tube, the input end of the inductor is connected to the control end of the charging control chip, the output end of the inductor is connected to the output interface, and the buck MOS tube is connected to the inductor.

[0014] Optionally, a protection MOS tube is further included, the input end of the protection MOS tube is connected to the inductor, and the output end of the protection MOS tube is connected to the output interface.

[0015] Compared with the prior art, the beneficial effects of the input undervoltage protection and auxiliary light-off circuit and the power adapter provided by the embodiments of the present invention are: by designing an input undervoltage protection and auxiliary light-off circuit, applied to the power adapter, when the voltage input to the mains input end is lower than the preset voltage, the input undervoltage protection is triggered, and the voltage input to the mains input end will enter the voltage-stabilizing diode through the rectifier diode and the second voltage divider module, and break down the voltage-stabilizing diode. Since the voltage cannot reach the turn-on condition of the first MOS tube, the first MOS tube is not turned on, so that the PWM control chip in the power adapter is pulled down by the second MOS tube, the PWM control chip stops working, and the primary-end voltage of the transformer will not be able to be transmitted to its secondary end, so as to achieve undervoltage protection and turn off the power indicator light. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments, in which:

[0017] Figure 1 is a circuit diagram of an input undervoltage protection and auxiliary light-off circuit provided by an embodiment of the present invention;

[0018] Figure 2 The circuit of the power adapter provided by the embodiment of the present invention is Figure 1 ;

[0019] Figure 3 The circuit of the power adapter provided by the embodiment of the present invention is Figure 2 ;

[0020] Figure 4 The circuit of the power adapter provided by the embodiment of the present invention is Figure 3 . DETAILED DESCRIPTION

[0021] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. Now, in conjunction with the accompanying drawings, the preferred embodiments of the present invention are described in detail.

[0022] like Figure 1 As shown, the present invention provides a specific embodiment of an input undervoltage protection and auxiliary light-off circuit.

[0023] An input undervoltage protection and auxiliary light-off circuit, used in power adapters, reference Figure 1 The input undervoltage protection and auxiliary light-off circuit includes a rectifier diode D3, a second voltage divider module 2, a voltage regulator diode ZD4, a first MOS tube M9, a second MOS tube M10 and a first voltage divider module 1.

[0024] Among them, reference Figure 1The input end of the rectifier diode D3 is connected to the AC input end 10 of the power adapter, the output end of the rectifier diode D3 is connected to the cathode of the voltage regulator diode ZD4 through the second voltage divider module 2, the anode of the voltage regulator diode ZD4 is connected to the gate G of the first MOS tube M9, the drain D of the first MOS tube M9 and the gate G of the second MOS tube M10 are both connected to the output end of the first voltage divider module 1, the input end of the first voltage divider module 1 is connected to the primary end of the transformer 20 of the power adapter, the source S of the first MOS tube M9 and the source S of the second MOS tube M10 are both grounded, and the drain D of the second MOS tube M10 is connected to the PWM control chip 30 of the power adapter.

[0025] Specifically, refer to Figure 1 The input undervoltage protection and auxiliary light-off circuit is mainly used in a power adapter. The power adapter includes a mains input terminal 10, a PWM control chip 30 and a transformer 20. The mains input terminal 10 is used to input grid power. The primary end of the transformer 20 is connected to the mains input terminal 10 to obtain the voltage input by the mains input terminal 10. The transformer 20 is used to transform the voltage input by the mains input terminal 10 and output it through its secondary end to power other functional modules (such as the power indicator light) in the power adapter and external devices.

[0026] Further, refer to Figure 1 The control end of the PWM control chip 30 is connected to the primary end of the transformer 20. The PWM control chip 30 can control the on and off time of its switch tube by adjusting the duty cycle of the PWM signal, thereby controlling the changes in the current and magnetic field in the primary end coil of the transformer 20. The transformation ratio of the transformer 20 will transfer the magnetic field transformation of the primary end coil to the secondary end coil, thereby changing the output voltage.

[0027] Further, refer to Figure 1 The input undervoltage protection and auxiliary light-off circuit includes a rectifier diode D3, a voltage regulator diode ZD4, a first MOS tube M9, a second MOS tube M10 and a first voltage divider module 1; the voltage input end of the rectifier diode D3 is connected to the mains input end 10, and the voltage output end of the rectifier diode D3 is connected to the cathode of the voltage regulator diode ZD4. The rectifier diode D3 is a half-wave rectifier, so as to rectify the AC voltage input from the mains input end 10 into a DC voltage, and output it to the second voltage divider module 2.

[0028] Further, refer to Figure 1Since the voltage-stabilizing diode ZD4 has a very stable voltage characteristic within its reverse breakdown voltage range, when the voltage exceeds its reverse breakdown voltage, the voltage-stabilizing diode ZD4 will be turned on to keep the voltage in the circuit at a stable level; by connecting the voltage output end of the rectifier diode D3 to the input end of the second voltage-dividing module 2, connecting the cathode of the voltage-stabilizing diode ZD4 to the output end of the second voltage-dividing module 2, and connecting the anode of the voltage-stabilizing diode ZD4 to the gate G of the first MOS tube M9, when the undervoltage protection is triggered, the voltage at the mains input end 10 will be rectified by the rectifier diode D3 and output a DC voltage and output to the voltage-stabilizing diode ZD4 through the second voltage-dividing module 2, so that the voltage-stabilizing diode ZD4 breaks down and turns on, and since the voltage does not reach the turn-on condition of the first MOS tube M9, the first MOS tube M9 does not turn on.

[0029] Further, refer to Figure 1 , the gate G of the first MOS tube M9 is connected to the positive electrode of the voltage-stabilizing diode ZD4, the drain D of the first MOS tube M9 is connected to the output end of the first voltage-dividing module 1, the source S of the first MOS tube M9 is grounded, and a capacitor C70 is connected in parallel to the gate G of the first MOS tube M9. When the voltage-stabilizing diode ZD4 breaks down and conducts, the voltage between the positive electrode of the capacitor C70 and the gate G of the first MOS tube M9 is equal to the difference between the output voltage of the rectifier diode D3 and the breakdown voltage of the voltage-stabilizing diode ZD4. The voltage difference cannot reach the turn-on voltage value of the first MOS tube M9, and the first MOS tube M9 is not turned on.

[0030] Further, refer to Figure 1 , the gate G of the second MOS tube M10 is connected to the voltage output end of the voltage divider module, the drain D of the second MOS tube M10 is connected to the PWM control chip 30 of the power adapter, and the source S of the second MOS tube M10 is grounded; when the first MOS tube M9 is not turned on, the first voltage divider module 1 will output voltage to the gate G of the second MOS tube M10, and the drain D and source S of the second MOS tube M10 will be turned on; after the second MOS tube M10 is turned on, the PWM control chip 30 connected to the drain D of the second MOS tube M10 will be pulled down to the ground, forcing the PWM control chip 30 to stop working, and the voltage at the primary end of the transformer 20 will not be able to be output to the secondary end of the transformer 20, thereby realizing input undervoltage protection.

[0031] Among them, the circuit can realize undervoltage protection and turn off the power indicator light in time to prevent the power indicator light from giving an error message; when the first MOS tube M9 is not turned on, the voltage divider module will output voltage to the gate G of the second MOS tube M10, and the drain D and source S of the second MOS tube M10 will be turned on; after the second MOS tube M10 is turned on, the PWM control chip 30 connected to the drain D of the second MOS tube M10 will be pulled down to the ground, forcing the PWM control chip 30 to stop working, and the voltage at the primary end of the transformer 20 will not be able to be output to the secondary end of the transformer 20, so that the power indicator light that needs to be powered by the secondary end of the transformer 20 can no longer obtain electrical energy from the secondary end of the transformer 20, and the power indicator light is quickly turned off.

[0032] Further, refer to Figure 1 The first voltage divider module 1 includes a first resistor R69, a second resistor R70 and a third resistor R71 connected in series, one end of the first resistor R69 is connected to the primary end of the transformer 20, the other end of the first resistor R69 is connected to one end of the second resistor R70, the other end of the second resistor R70 is connected to one end of the third resistor R71, the other end of the third resistor R71 is grounded, and the drain D of the second MOS tube M10 is connected between the second resistor R70 and the third resistor R71.

[0033] Currently, the power adapters or chargers on the market generally do not have the functions of input undervoltage protection and quick power-off light-off. Such products have certain defects. On the one hand, when the power supply is designed for 200-240VAC rated input working conditions, if there is no input undervoltage protection function, when the power supply is applied to low voltage input scenarios (such as 120V), the power supply will heat up seriously or even be damaged; on the other hand, when the power is cut off, the electric energy stored in the electrolytic capacitor on the primary side of the transformer will continue to be transmitted to its secondary side, making it difficult for the power indicator light to be extinguished in time, which is easy to cause error signals.

[0034] In this embodiment, an input undervoltage protection and auxiliary light-off circuit is designed and applied to a power adapter. When the voltage input to the mains input terminal is lower than the preset voltage, the input undervoltage protection is triggered, and the voltage input to the mains input terminal will pass through the rectifier diode and the second voltage divider module into the voltage regulator diode, and break down the voltage regulator diode. Since the voltage does not reach the turn-on condition of the first MOS tube, the first MOS tube is not turned on, so that the PWM control chip in the power adapter is pulled down by the second MOS tube, the PWM control chip stops working, and the primary-end voltage of the transformer will not be able to be transmitted to its secondary end, so as to achieve undervoltage protection and turn off the power indicator light.

[0035] In one embodiment, reference Figure 1The input undervoltage protection and auxiliary light-off circuit also includes a second voltage divider module 2, the input end of the second voltage divider module 2 is connected to the output end of the rectifier diode D3, and the output end of the second voltage divider module 2 is connected to the cathode of the voltage regulator diode ZD4.

[0036] Specifically, refer to Figure 1 The input undervoltage protection and auxiliary light-off circuit also includes a second voltage divider module 2, which includes a fourth resistor R63, a fifth resistor R64 and a sixth resistor R65 connected in series, one end of the fourth resistor R63 is connected to the rectifier diode D3, the other end of the fourth resistor R63 is connected to one end of the fifth resistor R64, the other end of the fifth resistor R64 is connected to one end of the sixth resistor R65, the other end of the sixth resistor R65 is grounded, and the cathode of the voltage-stabilizing diode ZD4 is connected between the fifth resistor R64 and the sixth resistor R65.

[0037] In one embodiment, reference Figure 1 The drain electrode D of the first MOS tube M9 and the gate electrode G of the second MOS tube M10 are both connected between the second resistor R70 and the third resistor R71.

[0038] like Figures 2 to 4 As shown, the present invention also provides a specific embodiment of a power adapter.

[0039] A power adapter, reference Figure 2 The power adapter includes the above-mentioned input undervoltage protection and auxiliary light-off circuit, and also includes a mains input terminal 10, a transformer 20, a PWM control chip 30, a charging control chip 40 and an indicator light module 50. The input undervoltage protection and auxiliary light-off circuit are respectively connected to the voltage input terminal and the PWM control chip 30. The control end of the PWM control chip 30 is connected to the primary end of the transformer 20, the primary end of the transformer 20 is connected to the mains input terminal 10, the secondary end of the transformer 20 is connected to the charging control chip 40, and the control end of the voltage control chip is connected to the indicator light module 50.

[0040] Specifically, refer to Figure 2 The AC input terminal 10 is used to receive AC power from the power socket and to filter out noise, interference and fluctuations in the power grid, thereby protecting the power adapter and the equipment connected to the power adapter; the primary side of the transformer 20 is connected to the AC input terminal 10, and the secondary side of the transformer 20 is connected to the charging control chip 40 to convert the high-voltage AC power input from the AC input terminal 10 into the low-voltage AC power required for charging, and the voltage input terminal of the PWM control chip 30 is connected to the drain D of the second MOS tube M10 in the input undervoltage protection and auxiliary light-off circuit.

[0041] Further, refer to Figure 2The indicator light module 50 is used to display the working status and power-on status of the power adapter. The control end of the indicator light module 50 is connected to the control end of the charging control chip 40 to control the switch of the indicator light through the charging control chip 40.

[0042] When the system triggers the input undervoltage protection, the voltage input to the rectifier diode D3 and rectified by the rectifier diode D3, the voltage input to the voltage regulator diode ZD4 through the second voltage divider module 2 will be greater than the breakdown voltage of the voltage regulator diode ZD4, so that the voltage regulator diode ZD4 is broken down, and the first MOS tube M9 is not turned on. When the first MOS tube M9 is turned off, the voltage stored in the electrolytic capacitor on the primary side of the transformer 20 and the divided voltage of the voltage divider module are applied to the gate G of the second MOS tube M10, so that the second MOS tube M10 is turned on. The drain D of the second MOS tube M0 is connected to the voltage input terminal of the PWM control chip 30 in the power adapter, and the source S of the second MOS tube M10 is grounded. When the second MOS tube M10 is turned on, the voltage at the voltage input terminal of the PWM control chip 30 in the power adapter will be pulled to the ground, so that the PWM control chip 30 in the power adapter stops working, and the energy stored in the electrolytic capacitor on the primary side of the transformer 20 is no longer released to its secondary side through the transformer 20, which can not only disconnect the subsequent power supply, but also quickly turn off the indicator light on the secondary side of the transformer 20.

[0043] In one embodiment, reference Figure 2 The power adapter also includes a rectifier and filter module BR1 , a voltage input end of the rectifier and filter module BR1 is connected to the mains input end 10 , and a voltage output end of the rectifier and filter module BR1 is connected to the primary end of the transformer 20 .

[0044] Specifically, refer to Figure 2 The rectifier and filter module BR1 includes a full-wave rectifier bridge for rectification, which includes four diodes and is connected in a bridge configuration, which allows current to pass in two directions, so that the rectifier bridge can simultaneously utilize the positive half-cycle and negative half-cycle AC signals to improve the rectification efficiency.

[0045] In one embodiment, reference Figure 2 A first energy storage capacitor is arranged between the rectifier and filter module BR1 and the primary end of the transformer 20, and the output end of the first energy storage capacitor is connected to the input end of the first voltage divider module 1; a second energy storage capacitor is also arranged between the secondary end of the transformer 20 and the charging control chip 40, and the output end of the second energy storage capacitor is connected to the voltage input pin of the charging control chip 40.

[0046] Specifically, refer to Figure 2Specifically, two first energy storage capacitors can be set, namely EC1 and EC2, EC1 and EC2 are connected in parallel and are set together at the primary end of the transformer 20, the input ends of the first energy storage capacitors EC1 and EC2 are connected to the voltage output end of the AC input end 10, the output ends of the first energy storage capacitors EC1 and EC2 are connected to the voltage input end of the first voltage divider module 1, and the second energy storage capacitors can be set specifically. Two, namely EC3 and EC4, EC3 and EC4 are connected in parallel, and the output ends after parallel connection are connected to the voltage input end of the charging control chip 40.

[0047] In one embodiment, reference Figure 3 The charging control chip 40 includes a voltage input pin VIN and a control pin GPIO1. The voltage input pin VIN of the charging control chip 40 serves as its voltage input terminal and is connected to the secondary terminal of the transformer 20 to obtain electric energy. The control pin GPIO1 of the charging control chip 40 serves as its control terminal and is used to connect to the indicator light module 50 to control the switch of the indicator light module 50.

[0048] In one embodiment, reference Figure 3 A third MOS tube M11 is provided between the charging control chip 40 and the indicator light module 50 , a gate G of the third MOS tube M11 is connected to the control terminal GPIO1 of the charging control chip 40 , a source S of the third MOS tube M11 is grounded, and a drain D of the third MOS tube M11 is connected to the indicator light module 50 .

[0049] Specifically, refer to Figure 3 When the energy of the first energy storage capacitor on the primary side of the transformer 20 is no longer released to its secondary side through the transformer 20, the voltage input terminal VCC of the charging control chip 40 will detect that the voltage on the secondary side of the transformer 20 is lower than the voltage required for the normal operation of the power adapter, and the control terminal GPIO1 of the charging control chip 40 will output a low level to the third MOS tube M11, the third MOS tube M11 is turned off, and the indicator light is turned off, further accelerating the speed of turning off the light.

[0050] In one embodiment, reference Figure 4 The power adapter also includes an output interface 60, an inductor L2, and upper and lower MOS tubes M2 and M4. The input ends of the upper and lower MOS tubes M2 and M4 are connected to the control end of the charging control chip 40, and the output ends of the upper and lower MOS tubes M2 and M4 are connected to the output interface 60 to cooperate with the inductor L2 to achieve voltage reduction.

[0051] Specifically, refer to Figure 4 The voltage input end of the output interface 60 is connected to the voltage output end of the charging control chip 40 to obtain electric energy, and the protection MOS tube M3 is arranged between the charging control chip 40 and the input interface to perform charging and discharging protection.

[0052] It should be understood that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. For those skilled in the art, the technical solutions described in the above embodiments can be modified, or some of the technical features therein can be replaced by equivalents; and all these modifications and replacements should fall within the protection scope of the claims attached to the present invention.

Claims

1. An input undervoltage protection and auxiliary light-off circuit, applied to a power adapter, characterized in that: include: A rectifier diode, a second voltage divider module, a voltage regulator diode, a first MOS tube, a second MOS tube and a first voltage divider module, wherein the input end of the rectifier diode is connected to the AC input end of the power adapter, the output end of the rectifier diode is connected to the input end of the second voltage divider module, the output end of the second voltage divider module is connected to the negative electrode of the voltage regulator diode, the positive electrode of the voltage regulator diode is connected to the gate of the first MOS tube, the drain of the first MOS tube and the gate of the second MOS tube are both connected to the output end of the first voltage divider module, the input end of the first voltage divider module is connected to the primary end of the transformer of the power adapter, the source of the first MOS tube and the source of the second MOS tube are both grounded, and the drain of the second MOS tube is connected to the PWM control chip of the power adapter.

2. The input undervoltage protection and auxiliary light-off circuit according to claim 1, characterized in that: The first voltage divider module includes a first resistor, a second resistor and a third resistor connected in series, and the drain of the first MOS tube and the gate of the second MOS tube are both connected between the second resistor and the third resistor.

3. The input undervoltage protection and auxiliary light-off circuit according to claim 1, characterized in that: The second voltage-dividing module includes a fourth resistor, a fifth resistor, and a sixth resistor connected in series, and the cathode of the voltage-stabilizing diode is connected between the fifth resistor and the sixth resistor.

4. A power adapter, characterized in that: It comprises the input undervoltage protection and auxiliary light-off circuit as described in any one of claims 1 to 4, and also comprises a mains input terminal, a transformer, a PWM control chip, a charging control chip and an indicator light module, the input undervoltage protection and auxiliary light-off circuit are respectively connected to the voltage input terminal and the PWM control chip, the control end of the PWM control chip is connected to the primary end of the transformer, the primary end of the transformer is connected to the mains input terminal, the secondary end of the transformer is connected to the charging control chip, and the control end of the voltage control chip is connected to the indicator light module.

5. The power adapter according to claim 4, characterized in that: It also includes a rectifier and filter module, wherein a voltage input end of the rectifier and filter module is connected to the mains input end, and a voltage output end of the rectifier and filter module is connected to the primary end of the transformer.

6. The power adapter according to claim 5, wherein a first energy storage capacitor is arranged between the rectifier and filter module and the primary end of the transformer, and an output end of the first energy storage capacitor is connected to an input end of the first voltage divider module.

7. The power adapter according to claim 5, characterized in that: A second energy storage capacitor is further provided between the secondary end of the transformer and the charging control chip, and an output end of the second energy storage capacitor is connected to a voltage input pin of the charging control chip.

8. The power adapter according to claim 5, characterized in that: A third MOS tube is arranged between the charging control chip and the indicator light module, the gate of the third MOS tube is connected to the control end of the charging control chip, the source of the third MOS tube is grounded, and the drain of the third MOS tube is connected to the indicator light module.

9. The power adapter according to claim 5, characterized in that: It also includes an output interface, an inductor and a step-down MOS tube, the input end of the inductor is connected to the control end of the charging control chip, the output end of the inductor is connected to the output interface, and the step-down MOS tube is connected to the inductor.

10. The power adapter according to claim 9, characterized in that: It also includes a protection MOS tube, the input end of the protection MOS tube is connected to the inductor, and the output end of the protection MOS tube is connected to the output interface.

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