Current limit for charge pump boost driven class d audio amplifier

A speaker system comprising:

• a first amplifier having a differential first amplifier input and a differential first amplifier output, the differential first amplifier input adapted to be coupled to an audio input source;
• a multiplexer having first and second mux inputs, a control input and a mux output, the first mux input coupled to the differential first amplifier output;
• a signal generator having a generator input and a generator output, the generator input coupled to the mux output;
• and
• a driver circuit having a driver circuit input and a driver circuit output, the driver circuit input is coupled to the generator output, and the driver circuit output is differential and coupled to first and second speaker drive terminals;
• a speaker having first and second speaker terminals coupled to the first and second speaker drive terminals, respectively;
• and
• a second amplifier having first and second error inputs and an error output, the first error input coupled to a current sense terminal configured to provide a voltage proportional to a power supply current, the second error input coupled to a current limit terminal configured to provide a reference voltage proportional to a current limit value.

An audio amplifier circuit comprising:

• a first amplifier having a differential first amplifier input and a differential first amplifier output, the differential first amplifier input adapted to be coupled to an audio input source;
• a multiplexer having first and second mux inputs, a control input and a mux output, the first mux input coupled to the differential first amplifier output;
• a signal generator having a generator input and a generator output, the generator input coupled to the mux output;
• and
• a driver circuit having a driver circuit input and a driver circuit output, the driver circuit input is coupled to the generator output, and the driver circuit output is differential and coupled to first and second speaker drive terminals;
• and
• a second amplifier having first and second error inputs and an error output, the first error input coupled to a current sense terminal configured to provide a voltage proportional to a power supply current, the second error input coupled to a current limit terminal configured to provide a reference voltage proportional to a current limit value;
• wherein, the multiplexer selects the first mux input when the power supply current is less than the current limit value, and selects the second mux input when the power supply current is greater than the current limit value.