Patent ID: 7515446

Claim:
A DC to AC inverter circuit, comprising: an input DC voltage source; a plurality of switches for selectively passing said DC voltage source; a transformer having a primary side and a secondary side, said primary side being selectively coupled to said DC voltage source and receiving DC voltage from said DC voltage source in an alternating fashion through said switches; a capacitor divider electrically coupled to a cold cathode fluorescent lamp load for providing a first voltage signal representing a voltage across said cold cathode fluorescent lamp load; a timer circuit coupled to said capacitor divider for providing a time-out sequence of a predetermined duration when said first voltage signal exceeds a predetermined threshold; a protection circuit coupled to said timer circuit for shuting down said plurality of switches when said first voltage signal exceeds said predetermined threshold for said predetermined duration; and a feedback control loop circuit coupled to said plurality of switches for receiving a feedback signal indicative of power being supplied to said cold cathode fluorescent lamp load from a component receiving current from said secondary side and for controlling a conduction state of at least one of said switches so that said switches have a plurality of operating modes comprising a first mode in which said switches deliver an amount of power to said cold cathode fluorescent lamp load determined by said feedback signal, and a second mode in which said switches deliver a predetermined minimum power to said cold cathode fluorescent lamp load for a predetermined time duration.