Patent ID: 9634621
Date: 2017-04-25
CPC Classifications: H02M,H03F,Y02B

Claim:
1. An audio amplifier 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 power supply input, wherein the power amplifier may generate the output signal based on the audio input signal; a charge pump power supply configured to provide a power supply voltage to the power supply input, wherein the charge pump power supply has a select input for selecting a selected operating mode of the charge pump power supply from a plurality of operating modes comprising a first operating mode and a second operating mode, such that in the first operating mode, the power supply voltage is equal to a first voltage, and such that in the second operating mode the power supply voltage is equal to a fraction of the first voltage; and a control circuit for generating the select input based on a magnitude of the power supply voltage and a magnitude of the output signal, such that the charge pump power supply operates in an operating mode of the plurality of operating modes having the lowest power supply voltage in which a difference between a magnitude of the power supply voltage and a magnitude of the output signal is more than the predetermined threshold voltage.