Charger, Terminal Device, and Charging System

A charger, comprising:

• a power conversion circuit comprising:
• a transformer;
• and
• a rectifier, wherein an alternating current is input from a primary side of the transformer, wherein the alternating current is induced to a secondary side of the transformer by the primary side of the transformer, and wherein a direct current is output from the secondary side of the transformer after the alternating current is rectified by the rectifier;
• a charging interface coupled to the power conversion circuit and comprising:
• a power cable;
• a ground cable;
• and
• a signal cable, wherein a positive electrode of the rectifier is connected to the power cable, and wherein a negative electrode of the rectifier is connected to the ground cable;
• an overcurrent protection circuit coupled to the power conversion circuit and comprising:
• an overcurrent detection circuit;
• and
• a pulse width modulation (PWM) control chip,
• wherein the overcurrent detection circuit is configured to enable the PWM control chip to control the primary side of the transformer to stop inducing the alternating current to the secondary side of the transformer when it is detected that a current of the secondary side of the transformer is greater than or equal to a first current threshold that is preset, and wherein the first current threshold is greater than a rated output current value of the charger;
• a resistor, wherein a first end of the resistor is connected to the power cable, and wherein a second end of the resistor is connected to the signal cable, wherein the overcurrent protection circuit further comprises a metal-oxide-semiconductor field effect transistor (MOSFET), wherein a first end of the MOSFET is connected to a control pin of the PWM control chip, wherein a second end of the MOSFET is connected to the primary side of the transformer to control working state of the primary side of the transformer, wherein the MOSFET is turned off when a voltage of the first end of the MOSFET is less than or equal to a third voltage threshold such that the primary side of the transformer stops inducing the alternating current to the secondary side of the transformer, wherein the third voltage threshold is greater than 0 volt (V) and is less than a working voltage of the PWM control chip, wherein the charger further comprises a switch device, and an isolation control device, wherein a first end of the switch device is connected to the signal cable, wherein a second end of the switch device is connected to a first input end of the isolation control device, wherein a third end of the switch device is connected to a ground, wherein the switch device is turned on to trigger the isolation control device to work when a voltage difference obtained by subtracting a voltage of the first end of the switch device from a voltage of the second end of the switch device is greater than or equal to a preset first voltage threshold, wherein the first voltage threshold is greater than 0 V and is less than an output voltage value of the power cable, wherein a second input end of the isolation control device is connected to the power cable, wherein a first output end of the isolation control device is connected to the control pin of the PWM control chip, wherein a second output end of the isolation control device is connected to the ground, and wherein the isolation control device is triggered to work such that a voltage of the first output end of the isolation control device is less than the third voltage threshold when the switch device is turned on.

A terminal device, comprising:

• a charging input circuit;
• an apparatus coupled to the charging input circuit and for controlling a charging micro short circuit;
• a battery coupled to the charging input circuit;
• and
• an application processor coupled to the apparatus,
• wherein the charging input circuit is configured to charge the battery,
• wherein the apparatus for controlling the charging micro short circuit comprises:
• a voltage comparator;
• and
• a processor coupled to the voltage comparator,
• wherein the voltage comparator is configured to:
• acquire a voltage of a power cable of the charging input circuit and a voltage of a signal cable of the charging input circuit;
• and
• obtain a difference by subtracting the voltage of the signal cable of the charging input circuit from the voltage of the power cable of the charging input circuit,
• wherein the processor is configured to:
• determine, according to the difference, whether the micro short circuit occurs on the charging input circuit;
• and
• send, to the application processor, a signal indicating that the micro short circuit occurs on the charging input circuit, and
• wherein the application processor is configured to control an output device of the terminal device to emit an alert signal to prompt an owner of the terminal device that the micro short circuit occurs on the charging input circuit of the terminal device.