PUBLIC ADDRESS SYSTEM PROVIDING POWER SAVING FUNCTION AND SPEAKER PROTECTING FUNCTION CONCURRENTLY AND POWER SAVING CIRCUIT USED THEREIN

摘要

The present invention relates to a public address system for simultaneously providing a power saving function and a speaker protection function, and a power saving circuit used therein wherein the public address system comprises: a DC/DC converter for converting a voltage of a DC power to a driving voltage of a main amplifier and thereby providing to the main amplifier; a signal generator for generating a Pulse Width Modulation (PWM) signal required for driving the DC/DC converter; and a power saving circuit for starting a power supply to the signal generator from a point of time when a size of a signal inputted from a sound source is in excess of a threshold value corresponding to a minimum size of an audio signal, and for suspending a power supply to the signal generator if a predetermined time has passed from a point of time when a size of signal inputted from a sound source is less than a threshold value.