Patent ID: 7808324

Claim:
An audio amplifier integrated circuit for providing an output signal to an audio transducer, the audio amplifier circuit comprising: a power amplifier having an audio input for receiving an audio input signal, an audio output for providing the output signal, and a pair of power supply rail connections; a charge pump power supply for providing a power supply voltage across the pair of power supply rail connections of the power amplifier, wherein the charge pump power supply has a selectable operating mode for selecting a magnitude of the power supply voltage; and a control circuit for selecting the operating mode of the charge pump power supply in conformity with an indication of an amplitude of the audio input signal and further in conformity with an indication of an operating environment of the audio amplifier integrated circuit or a position within a process variation range of the audio amplifier integrated circuit, whereby efficiency of the audio amplifier integrated circuit is improved while clipping of the output signal is prevented.