Patent ID: 6639366
Filing Date: 2003-10-28
Classification: H05B,Y10S

Abstract:
A power supply circuit for a cold-cathode fluorescent lamp (CCFL), the power supply circuit being coupled to a DC (Direct Current) voltage output circuit and the CCFL, the DC voltage output circuit outputting a low DC voltage, and the power supply circuit converting the low DC voltage to a high AC voltage for driving the CCFL, the power supply circuit comprising:a switch comprising a control node, a ground node, and a signal node; a switch control circuit coupled to the control node, for outputting a control signal to control the on/off status of the switch; a transformer having a primary side and a secondary side, the primary side having a first node and a second node, the secondary side having a third node and a fourth node, the first node coupled to the DC voltage output circuit, the second node coupled to the signal node of the switch; an energy-preserving unit for preserving electrical energy, having a fifth node and a sixth node, the fifth node being coupled to the first node of the primary side of the transformer and the DC voltage output circuit; and a decoupling capacitor coupled to the third node of the secondary side of the transformer for outputting the high AC voltage.