Patent ID: 9525294
Filing Date: 2016-12-20
CPC Classification: G06F,H02J

Claim Text:
1. A charging control circuit of universal serial bus (USB) device, wherein the USB device is coupled to an external charger and a battery device, the USB device comprises a core circuit having a first pin and a second pin, and the charging control circuit comprises: a voltage source, arranged for selectively coupling to one of the first pin and the second pin according to a switch control signal; wherein input impedance looking into the core circuit from the first pin and the second pin is configured to make the voltage source substantially intact when the voltage source is coupled to at least one of the first pin and the second pin; wherein when the external charger provides a first supply voltage to charge the battery device to make the battery device generate a battery output voltage, the charging control circuit is arranged to be powered up by the first supply voltage, and the switch control signal is generated in response to a second supply voltage derived from the battery output voltage.