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Separate control of the operation of an audio amplifier and a charge pump that synthesizes a negative voltage supply (VSS) for improving the dynamic range of the audio amplifier. The audio amplifier is typically powered by a single positive power supply (VDD) and the charge pump is arranged to synth

Separate control of the operation of an audio amplifier and a charge pump that synthesizes a negative voltage supply (VSS) for improving the dynamic range of the audio amplifier. The audio amplifier is typically powered by a single positive power supply (VDD) and the charge pump is arranged to synthesize a negative voltage supply rail (VSS) that enables a greater dynamic range for the amplifier's “on” and “shut down” modes of operation. Also, when the audio amplifier enters its shut down mode of operation to create at least some isolation from Line_In audio signals provided at the amplifier's output by other electronic devices, the amplifier's charge pump stays “on” and continues to provide the negative voltage supply rail (VSS). In this way, the greater dynamic range offered by the presence of both the positive and negative voltage rails is provided even if the amplifier is in a shut down mode.

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1. An apparatus for audio amplification, operable with at least one Line-In device, comprising: an audio amplifier circuit configured to receive an audio signal and output an amplified audio signal at an output, the audio amplifier circuit operable in: an on mode in which the received audio signal i

1. An apparatus for audio amplification, operable with at least one Line-In device, comprising: an audio amplifier circuit configured to receive an audio signal and output an amplified audio signal at an output, the audio amplifier circuit operable in: an on mode in which the received audio signal is amplified and the amplified audio signal is output, anda shutdown mode in which at least some circuitry associated with amplification and outputting an amplified audio signal is disabled;a charge pump circuit for generating the negative voltage supply based on a positive voltage supply;a first diode coupled between the output of the audio amplifier circuit and the positive voltage supply, and a second diode coupled between the output of the audio amplifier circuit and the negative voltage supply; anda control circuit that is arranged to separately control (i) the on and shutdown modes of operation for the audio amplifier circuit, and (ii) the charge pump circuit;wherein the control circuit is operative to concurrently enable the operation of the charge pump circuit to generate the negative voltage supply and enable operation of the audio amplifier circuit in the shut down mode, thereby enabling the audio amplifier circuit, in the shutdown mode, to present to Line-In audio signals from the at least one Line-In device coupled to the output of the audio amplifier circuit a dynamic range between the positive and negative voltages as in the on mode. 2. The apparatus of claim 1, wherein the control circuit further comprises an external interface that is arranged to communicate by at least one of a digital signal, analog signal, serial control signal, parallel signal, inter-integrated circuit bus, or 12C bus. 3. The apparatus of claim 1, wherein the control circuit further comprises at least one control signal that establishes at least one of an on mode of operation and the shut down mode of operation for the audio amplifier circuit. 4. The apparatus of claim 1, wherein the control circuit further comprises at least one control signal that enables the operation of the charge pump circuit, and another control signal that disables the operation of the charge pump circuit. 5. The apparatus of claim 1, further comprising a flying capacitor that has both ends coupled to the charge pump circuit. 6. The apparatus of claim 1, further comprising at least a holding capacitor that has one end coupled to the charge pump circuit and the negative voltage supply and another end coupled to ground. 7. The apparatus of claim 1, wherein at least one of the first diode and the second diode are arranged to prevent a deleterious effect from an electrostatic discharge. 8. The apparatus of claim 1, further comprising a node that is coupled to the output of the audio amplifier, wherein the node is adapted for connecting to at least one external electronic device, and wherein the external electronic device provides at least a Line_In audio signal at the node. 9. The apparatus of claim 1, wherein the apparatus is an integrated circuit. 10. A method for audio amplification in a system with an audio amplifier circuit coupled at an output to at least on Line-In device, the audio amplifier circuit operable in an on mode in which audio amplification is enabled to output an amplified audio signal, and a shutdown mode in which audio amplification to output an amplified audio signal is disabled, the audio amplifier circuit including a charge pump circuit for generating a negative voltage supply based on a positive voltage supply, comprising: selectively controlling the audio amplifier circuit to operate in the on mode, while enabling the charge pump to generate the negative voltage supply; andselectively controlling the audio amplifier circuit to operate in the shutdown mode, while enabling the charge pump to generate the negative voltage supply;thereby enabling the audio amplifier circuit, in the shutdown mode, to present to Line-In audio signals from the at least one Line-In device a dynamic range between the positive and negative voltages as in the on mode. 11. The method of claim 10, further comprising detecting if the Line_In audio signal is provided at the output of the audio amplifier circuit. 12. The method of claim 10, further comprising reducing deleterious effects from electrostatic discharge with at least one diode coupled between the audio amplifier circuit's output and the positive voltage supply and at least another diode coupled between the audio amplifier circuit's output and the negative voltage supply. 13. A system for audio amplification, comprising: an audio amplifier coupled at an output to at least one Line-In device;the audio amplifier configured to receive an audio signal and output an amplified audio signal, the audio amplifier circuit operable in an on mode in which the received audio signal is amplified and the amplified audio signal is output, anda shutdown mode in which at least some circuitry associated with amplification and outputting an amplified audio signal is disabled;a charge pump circuit for generating the negative voltage supply based on a positive voltage supply;a first diode coupled between the output of the audio amplifier and the positive voltage supply, and a second diode coupled between the output of the audio amplifier arid the negative voltage supply; anda control circuit that is arranged to separately control (i) the on and shutdown modes of operation for the audio amplifier, and (ii) the charge pump circuit;wherein the control circuit is operative to concurrently enable the operation of the charge pump circuit to generate the negative voltage supply and enable the audio amplifier in the shut down mode, thereby enabling the audio amplifier, in the shutdown mode, to present to Line-In audio signals from the at least one Line-In device a dynamic range between the positive and negative voltages as in the on mode. 14. The system of claim 13, wherein the control circuit further comprises an external interface that is arranged to communicate by at least one of a digital signal, analog signal, serial control signal, parallel signal, inter-integrated circuit bus, or I2C bus.