Patent ID: 7158811

Claim:
A circuit for supplying ear-microphone bias power to an ear/microphone having a call switch connected to an ear-microphone line in a mobile terminal, the circuit supplying ear-microphone bias power to the ear-microphone line and detecting a switching operation of the call switch based on a signal on the ear-microphone line, said circuit comprising: a first power input terminal through which first power is inputted, said first power being supplied when the mobile terminal is not in a sleep mode and not supplied when the mobile terminal is in the sleep mode, said first power having a voltage capable of being the ear-microphone bias power; a second power input terminal through which second power is inputted, said second power being supplied when the mobile terminal is in the sleep mode, said second power having a voltage that is lower than the voltage of the first power and being supplied as switching-operation detection power for detecting the switching operation of the call switch; and a power switching circuit for supplying the ear-microphone bias power based on the first power when the mobile terminal is not in the sleep mode, and supplying the switching-operation detection power based on the second power when the mobile terminal is in the sleep mode.