Patent ID: 7417382

Claim:
A DC to AC cold cathode fluorescent lamp inverter circuit, comprising: a step-up transformer with a primary winding and a secondary winding for providing increased voltage to a cold cathode fluorescent lamp; a first switch coupled to said step-up transformer for selectively allowing said step-up transformer to receive DC voltage of a first polarity; a second switch coupled to said step-up transformer for selectively allowing said step-up transformer to receive DC voltage of a second polarity; a capacitor divider electrically coupled to said cold cathode fluorescent lamp for providing a first voltage signal representing a voltage across said cold cathode fluorescent lamp; a first feedback signal line coupled to said capacitor divider for receiving said first voltage signal from said capacitor divider representing said voltage across said cold cathode fluorescent lamp; a timer circuit coupled to said first feedback signal line for providing a time-out sequence of a predetermined duration when said first voltage signal exceeds a predetermined threshold for said predetermined duration; and a protection circuit coupled to said timer circuit, said first switch and said second switch for shutting down said first switch and said second switch after said predetermined duration.