JP2869255B

PURPOSE:To prevent the generation of pop noise in rapid off/on operation of a standby switch. CONSTITUTION:When a standby switch 10 is opened, a level of a power supply Vcc' reaches an earth level rapidly. On the other hand, an intermediate potential Vd is gradually decreased by the action of a capacitor CDC. Thereby, when the standby switch 10 is opened, the intermediate potential Vd becomes higher than the standby power supply Vcc'. Thus, transistors (TRs) Q3, Q4, Q5 are turned on, the charge stored in an output capacitor COUT is discharged to ground via the TR Q5. Thus, the charge stored in the output capacitor COUT is rapidly discharged when the standby switch is turned off thereby preventing the generation of pop noise even when the standby switch is continuously turned on/off.