Patent ID: 7345465

Claim:
An apparatus for controlling the operation of a DC power supply comprising: a first input terminal adapted to be coupled to a first remote power supply terminal, through which a first of a pair of supply rail voltages is supplied to a first supply terminal for a powered device; a second input terminal adapted to be coupled to a second remote power supply terminal, through which a second of said pair of supply rail voltages is supplied to a second supply terminal for said powered device; and a control circuit, coupled to said first and second input terminals, and being operative to derive a current representative of a voltage differential between said first of said pair of supply rail voltages and a target value thereof, and to produce an offset voltage in accordance with said current, said offset voltage being used to modify a target value of said second of said pair of supply voltages to produce an error amplifier reference voltage that is compared in an error amplifier with a voltage derived by said second input terminal to produce an error voltage, in response to which a control loop for said DC power supply adjusts the power supply output, so as to ensure delivery of an appropriate value of said second of said pair of supply voltages to said second supply terminal of said powered device that maintains the intended DC voltage differential between said pair of supply rail voltages at said first and second supply terminals for said powered device.