Abstract: A voltage level detector (8) activates itself through monitoring the voltage level (VSTB) at a standby pin (5) during power-up of an audio power amplifier (10), and can detect fault conditions of an output block (2), such as a short to ground at an output terminal (3), in contrast to conventional protection circuits that can operate only after power-up. In a voltage level detector (8), a second short-to-ground detection block (81) monitors the voltage levels (VSTB and Vout) at the standby pin (5) and the output terminal (3) during power-up. Upon detection of the voltage level (VSTB) reaching a first threshold level (Vth1) and a short to ground at the output terminal (3), the second short-to-ground detection block (81) activates a cutoff signal generating block (83). The recovery block (82) monitors the voltage level (VSTB) at the standby pin (5) during power-up.