The charger converts 220V AC to positive 5V direct charge output to the power management module in the mobile phone, and the module controls the phase battery charging to 4.2V and then stops. USB charging directly takes out the positive 5V voltage provided by USB and provides it to the power management module of the mobile phone, eliminating the power conversion circuit of the charger. usb charging detection can be detected by adding hardware detection circuit on D,D-, and charging detection is identified by detecting the charger insertion signal.