| 摘要 |
PROBLEM TO BE SOLVED: To prevent various noises without complicating the circuit configuration. SOLUTION: A CPU 19 detects on/off of a power supply switch 18, exchanges control information with a sound processing IC 11, a reference voltage generator circuit 11a and a reference voltage generator circuit 14, switches a switch element 15 in accordance with states of the sound processing IC 11, the reference voltage generator circuit 11a and the reference voltage generator circuit 14, and interrupts the noise components caused by on/off of the power supply switch 18, the noise components caused by on/off of the reference voltage generator circuit 11a and the reference voltage generator circuit 14, and the noise component N7 when the sound signal is not outputted by switching the switch element 15. |
