Patent ID: 7986106

Claim:
A discharge lamp driving device for driving a plurality of lamps, the discharge lamp driving device comprising: a power stage circuit configured for transforming a received external signal to an alternating current (AC) signal; a transformer circuit connected to the power stage circuit and configured for transforming the AC signal to a plurality of electrical signals for driving the plurality of lamps; a protection circuit, comprising: a current sensing circuit connected to the lamps, and configured for sensing current signals flowing through the lamps, transforming the current signals to a plurality of voltage signals, and dividing the voltage signals into a plurality of divided voltage signals; a reference voltage selecting circuit connected to the current sensing circuit, and configured for comparing the plurality of voltage signals and generating a reference voltage signal based on a largest one of the voltage signals; a comparing circuit connected to the reference voltage selecting circuit and the current sensing circuit, and configured for comparing the reference voltage signal with the plurality of divided voltage signals and generating a plurality of comparing signals; and a protection signal generating circuit connected to the comparing circuit, and configured for generating a protection signal based on a largest one of the comparing signals; and a control circuit connected between the protection signal generating circuit and the power stage circuit, and configured for transforming the protection signal to a control signal to control the output of the AC signal by the power stage circuit.