Patent ID: 8476962

Claim:
A system coupled between a positive power supply terminal and a negative power supply terminal, wherein a full rail power supply voltage of the system is a voltage difference between a first power supply voltage at the positive power supply terminal and a second power supply voltage at the negative power supply terminal, the system comprising: a first circuit having a first power supply terminal coupled to the positive power supply terminal and a second power supply terminal; a first charge pump and regulator having an input coupled to the positive power supply terminal and an output coupled to the second power supply terminal of the first circuit; a second circuit having a first power supply terminal coupled to the second power supply terminal of the first circuit and a second power supply terminal; a second charge pump and regulator having an input coupled to the first power supply terminal of the second circuit and an output coupled to the second power supply terminal of the second circuit, wherein the first charge pump and regulator controls a first voltage drop across the first circuit and the second charge pump and regulator controls a second voltage drop across the second circuit independently of the first charge pump and regulator, and wherein the first charge pump and regulator determines if a minimum current requirement of the second circuit is met by detecting a voltage on the second power supply terminal of the first circuit; a third charge pump and regulator having an input and an output; and a control circuit to control voltage drops across the first circuit and the second circuit, and when a voltage dropped by circuits of the system coupled between the positive power supply terminal and the negative power supply terminal is not equal to the full rail power supply voltage, the third charge pump and regulator is controlled to make up a difference between the full rail power supply voltage and the voltage dropped by the circuits of the system.