Patent ID: 7402981

Claim:
An apparatus comprising: a converter within an integrated circuit to convert a battery voltage from a battery to an output voltage to power the integrated circuit in a battery-operated mode of operation, when the battery is made available to the integrated circuit, wherein the converter includes a switching transistor circuit to alternately switch transistors to regulate the output voltage in the battery-operated mode of operation and in a battery-charge mode of operation, but the switching transistor circuit is disabled in an external powered mode of operation, when external power is present and the battery is not to be charged; and a control unit to switch the converter in one of three modes, the battery-operated mode to convert the battery voltage to the output voltage when the external power is not present, the battery-charge mode to employ the external power to generate a current source to charge the battery and maintain the output voltage when the external power is present, and an external powered mode of operation to employ the external power to generate a voltage source to source the output voltage when the external power is present.