The AN7555NZ is an audio power IC developed as the sound output of car audio (35 W x 4-channel). It has realized the voltage gain of 40 dB based on the AN7560Z (voltage gain: 34 dB). A capacitor and resistor to stop oscillation are built in between the output pin and GND so that a space saving of set is possible. Also, it incorporates a perfect muting circuit without shock noise, so that a shock noise design under the set transient condition can be made easily when used together with its standby function. In addition, it incorporates various protection circuits to protect the IC from destruction by GND-open short circuit to ground, and power supply surge which are the important subject of power IC protection. This IC will largely contribute to a high reliability design of the equipment.