Patent ID: 8416017

Claim:
A Class D audio amplifier circuit comprising an audio signal input, a pulse width modulator (PWM) stage for converting the audio input signal to a series of pulses wherein the width of pulses in the series of pulses is representative of the audio input signal, a switching power output stage having a supply voltage input and being switchable between an “on” state and an “off” state in response to the series of pulses produced by said PWM stage for producing a series of amplified power output pulses corresponding to the series of pulses produced by said PWM stage, a main voltage supply for providing a voltage at the supply voltage input of said switching power output stage, and wherein the Class D amplifier has a gain determined by said supply voltage input, and power output stage voltage control means responsive to defined signal conditions of the audio signal input, said power output stage voltage control means being operative to lower the voltage at the supply voltage input of said switching power output stage, and thereby the gain of the Class D amplifier, upon the detection of a defined condition in the audio signal input and to hold the voltage at the supply voltage input in a lowered voltage condition for a period of time wherein the Class D amplifier operates at reduced voltage (“idles”) during such defined audio signal input condition.