Patent ID: 6522190
Filing Date: 2003-02-18
Classification: H02J,H02M,H03K

Abstract:
A power supply circuit including a first voltage source and a second voltage source, comprising:a first circuit coupled to the first voltage source, wherein the first circuit comprises: a first comparator for comparing a first voltage from the first voltage source with a second voltage from the second voltage source, a first transistor coupled to the first comparator, wherein the first transistor conducts when the first voltage is higher than the second voltage, and a second transistor coupled to the first transistor and the first voltage source, wherein the second transistor conducts when the first transistor conducts, wherein the first voltage is provided as an output voltage when the second transistor conducts; and a second circuit coupled to the second voltage source, wherein the second circuit comprises: a second comparator for comparing the second voltage with the first voltage, a third transistor coupled to the second comparator, wherein the third transistor conducts when the second voltage is higher than the first voltage, and a fourth transistor coupled to the third transistor and the second voltage source, wherein the fourth transistor conducts when the third transistor conducts, wherein the second voltage is provided as the output voltage when the fourth transistor conducts.