Charger and electronic device

A charger, configured to charge an electronic device, the charger comprising:

• a mains plug configured to connect to a mains supply;
• a voltage conversion unit comprising an input port, an output port, and a feedback port, wherein, the voltage conversion unit is connected to the mains plug via the input port and is configured to convert an AC voltage received by the mains plug to a DC voltage with a predetermined value;
• a first power port configured to connect to the electronic device, wherein, the first power port comprises a positive voltage pin, a negative voltage pin, and a control pin, the positive voltage pin is connected to the output port of the voltage conversion unit, the negative voltage pin is connected to the feedback port of the voltage conversion unit;
• a feedback resistor module connected between the negative voltage pin and ground;
• and
• a microprocessor comprising a detection port and a first control port, wherein, the detection port is connected to the control pin of the first power port and is configured to detect signals of the control pin;
• the first control port is connected to the feedback resistor module;
• wherein, the feedback port provides a constant voltage, a current output by the output port of the voltage conversion unit is equal to a ratio between the voltage of the feedback port and a resistance value of the feedback resistor module;
• the microprocessor decreases the resistance value of the feedback resistor module, when the detection port of the microprocessor detects a first control signal from the control pin of the first power port;
• the microprocessor further increases the resistance value of the feedback resistor module, when the detection port of the microprocessor detects the second control signal from the control pin of the first power port.