| 摘要 |
PROBLEM TO BE SOLVED: To suppress the generation of a pop sound caused by rapidly changing the potential of a smoothing capacitor installed on the prestage of a speaker when turning on an audio output device. SOLUTION: When turning on a power source, the potential of a smoothing capacitor installed on the prestage of a speaker is smoothly changed by controlling the potential with use of a PWM signal and switching between outputting the PWM signal and an actual audio signal, thereby suppressing a pop sound. The scale of circuitry is reduced and cost is lowered by assembling a PWM circuit and a control circuit for adjusting a potential, in a one-chip microcontroller that is made into LSI. Noise is eliminated by outputting pulses divided in the PWM signal generation stage. COPYRIGHT: (C)2007,JPO&INPIT
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