Voltage regulator with double synchronous bridge ccfl inverter

Abstract

An inverter circuit having dual converters for driving a fluorescent lamp comprising a pulse width modulator coupled to receive a feedback signal indicative of current in the fluorescent lamp. The pulse width modulator generates driving signals that are received by a synchronously switching voltage regulator having a high side driver and a low side driver. A self-resonant converter is coupled between the synchronously switching voltage regulator and the fluorescent lamp and generates a voltage signal for illuminating the fluorescent lamp. The self-resonant converter includes a transformer having a primary winding and at least one secondary winding, a capacitor coupled in parallel with the primary winding, and a full bridge circuit. The full bridge circuit may include four switching transistors, such as MOSFETs coupled in an H-configuration to the primary winding and the capacitor. A zero voltage detector controls switching of the synchronously switching voltage regulator based on voltage input to the self-resonant converter. A timer circuit is coupled to the self-resonant converter and the zero voltage detector, and outputs signals to control the frequency of oscillation in the self-resonant converter based on the signals from the self-resonant converter and the zero voltage detector.