Patent ID: 6940233
Filing Date: 2005-09-06
Classification: H05B

Abstract:
1. A CCFL circuit comprising: a PMOS transistor; first and second NMOS transistors; and a high turns ratio transformer, wherein the transformer includes a primary coil having a center tap forming a first primary winding and a second primary winding, and a single secondary coil, wherein a drain of the PMOS transistor is connected to the center tap and the source of the PMOS transistor is connected to a battery, wherein a drain of the first NMOS transistor is connected to an end of the first primary winding, a drain of the second NMOS transistor is connected to an end of the second primary winding, and sources of the first and second NMOS transistors are connected to a voltage source VSS, wherein the first primary winding is tightly coupled to the second primary winding, and wherein the first and second primary windings are loosely coupled to the secondary coil, thereby resulting in significant leakage inductance; and a CCFL tube, wherein the secondary coil is connected between voltage source VSS and the CCFL tube.