The SM1155 series are CMOS melody LSIs that, together with a battery and piezoelectric buzzer, operate in one of 3 melody modes determined by bonding options. They also feature an oscillator stop function in nonplay mode and a variable pull-down resistance function that responds to input levels in order to reduce power consumption, reduce cost, and extend battery life, making them ideal in a wide range of applications including the hold sound for telephones and toys.