Patent ID: 8659240

Claim:
A circuit for detecting a filament of a fluorescent lamp, wherein: a first end of a first filament of the fluorescent lamp is connected to a second end of the first filament via an oscillation circuit composed of a capacitor and an inductor, and the first end of the first filament is connected to an output of an inverter; a first end of a second filament of the fluorescent lamp is connected to a second end of the second filament via an oscillation circuit composed of a capacitor and an inductor, wherein the first end of the second filament is connected to the internal ground; wherein the second end of the second filament is connected to a power source via a first resistor, and a voltage at the second end of the second filament is used for controlling ON and OFF of an MOSFET, wherein a source of the MOSFET is connected to the internal ground, and a drain thereof is connected to the power source via a second resistor and a third resistor; and wherein a node between the second resistor and the third resistor is connected to a VCC pin of an integrated circuit.