Patent ID: 8860375

Claim:
A backup battery charger disposed in a handheld electronic device and configured to charge a backup battery in the handheld electronic device, the handheld electronic device having a power supply unit and an electronic component, the power supply unit supplying a power to the electronic component, the backup battery charger comprising: a charging power input end connected to the electronic component for receiving the power and using the power thus received as a charging power; and a control module having a first signal receiving end for receiving an external interruption control signal and being connected between the charging power input end and the backup battery for transmitting the charging power to the backup battery and interrupting transmission of the charging power to the backup battery based on the external interruption control signal; wherein the control module comprises an overcurrent protection control circuit, and the first signal receiving end cuts off the charging power passing through the overcurrent protection control circuit by using an overcurrent detection signal generated by an external overcurrent detection circuit and regarded as the interruption control signal.