Patent ID: 7064497

Claim:
A controller for providing a dead-time-modulated (DTM) synchronous pulse width modulation (PWM) to a dimmable cold-cathode fluorescent lamp (CCFL) Royer inverter, wherein a first and a second voltages are applied to said controller to generate an output voltage to control a switch for dimming said CCFL, comprising: a constant current charger (CCC) for generating said first voltage; a first comparator for comparing said second voltage with a first reference voltage to generate a trigger signal; a second comparator electrically connected to said first comparator for comparing said trigger signal with a second reference voltage; a third comparator electrically connected to said CCC for comparing said first voltage with a third reference voltage; a flip-flop electrically connected to said second comparator and said third comparator for generating a control signal in response to the outputs of said second and said third comparators; a discharger having a first terminal for receiving said control signal, a second terminal electrically connected to said CCC, and a third terminal electrically connected to a ground; a fourth comparator electrically connected to said CCC for comparing an error signal with said first voltage to generate a down-going error voltage; and a fifth comparator electrically connected to said CCC for comparing said error signal with said first voltage to generate an up-going error voltage, wherein said output voltage is one of said down-going and said up-going voltages.