| 摘要 |
PROBLEM TO BE SOLVED: To provide a pop noise reduction circuit for reducing a so-called "pop noise" caused when a standby mode of an audio power amplifier is released or when a power is turned ON/OFF and to provide a pop noise reduction system, a constant voltage circuit, and an amplifier circuit. SOLUTION: A maximum current generating circuit includes a sample-hold circuit comprising: a switch means SW for storing a voltage just before a signal GND voltage rises; a hold capacitor CH; and a voltage follower AMP 3. When a sleep signal ISLP is at a high level, the switch means is turned on and when the sleep signal ISLP is at a low level, the switch means is turned off. When a standby mode is released, the sleep signal goes to a low level to turn off the switch means thereby holding the voltage of the hold capacitor. The voltage of the hold capacitor is outputted from the voltage follower AMP 3. The maximum current generating circuit receives a reference voltage Va, an output voltage from the voltage follower AMP 3, and a signal GND voltage SGout and generates a current whose value is the same as that of a maximum output current capable of being outputted from a voltage follower AMP 2. COPYRIGHT: (C)2005,JPO&NCIPI
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