The LA4917H is a high-effciency two-channel 7W BTL power amplifier IC. Increases in the number of external components are held to a minimum by adopting both a signal-following type switching scheme in the amplifier's output stage power supply, and a nonlinear amplifier that has nonlinear characteristics in the signal system. The power dissipation (thermal loss) in the actual operating range has been reduced to about 1/2 that of earlier class B amplifier ICs. When used with the DIP-28H package, the IC dispenses with the heat sink and significantly contributes to space saving in the end product case.