Patent ID: 7560898

Claim:
A circuit for regulation, comprising: a first switch circuit that is coupled between a first input node and a switch node, wherein the first switch circuit has at least a control input, and wherein a first power source is connectable to the first input node; a first switching regulator controller circuit having at least a feedback input and an output, wherein the output of the first switching regulator controller circuit is coupled to the control input of the first switch circuit; a second switch circuit that is coupled between a second input node and the switch node, wherein the second switch circuit has at least a control input, and wherein a second power source is connectable to the second input node; a second switching regulator controller circuit having at least a feedback input and an output, wherein the output of the second switching regulator controller circuit is coupled to the control input of the second switch circuit; and a switching regulator selection control circuit having at least a first input and a second input, wherein the first input of the switching regulator selection control circuit is coupled to the first input node; the second input of the switching regulator selection control circuit is coupled to the second input node; and wherein the switching regulator selection control circuit is operable to control a disabling that is associated with the second switching regulator controller circuit if voltage is present at the first input of the switching regulator selection control circuit, and further operable to control a disabling that is associated with the first switching regulator controller circuit if voltage is present at the second input of the switching regulator selection control circuit and voltage is not present at the first input of the switching regulator selection control circuit.