Patent ID: 8582328
Filing Date: 2013-11-12
Classification: H02M,Y02B

Abstract:
1. A power supply circuit for providing a power voltage to a back-stage circuit, the power supply circuit comprising: a switching power circuit, controlling the power voltage; a closed loop feedback control that, in a normal mode, feeds back the power voltage to the switching power circuit in a closed loop; an open loop feedback control that, in a power saving mode, feeds back the power voltage to the switching power circuit in an open loop; and a transformer, having a primary side coupled to the switching power circuit, and a secondary side coupled to the back-stage circuit and the closed loop feedback control, wherein when the switching power circuit continuously detects the open loop and after the switching power circuit substantially enters in a zero output status for a delay period, the switching power circuit enters into a power down mode, the delay period related to voltage delay and voltage comparison, wherein the transformer couples an output voltage of the switching power circuit to the secondary side to generate the power voltage, and wherein the switching power circuit comprises