Abstract: A zero voltage switching power conversion circuit for driving a CCFL has a ZVS circuit and a full bridge circuit composing of MOS transistors. A transformer is coupled between the full bridge circuit and the CCFL. By properly controlling the conducting timing of each MOS transistor, power is coupled from the primary side to the secondary side of the transformer thus supplying power to the CCFL. When adjusting the brightness of the CCFL, the high frequency signal is able to be temporarily shut down during off periods of the CCFL to reduce power consumption.

Abstract: A low voltage constant current source is composed of a reference current circuit being insensitive to temperature variation, and multiple current output units in response to the reference current circuit to individually output a stable current. Each current output unit is individually controlled to be activated or not, and each output current is amplified in any desired ratio to a reference current generated by the reference current circuit. Moreover, since each current unit is operated independently, the interference among each other is avoided when each output unit is applied in the open-collector.