Circuit device

Abstract

The invention relates to a circuit for operating a high-pressure discharge lamp, which circuit is provided with means for operating the connected lamp in a dimmed state by means of a dimming signal Ds. The circuit is provided with: input terminals for connecting the circuit to a power supply source, output terminals for connecting the lamp to be operated, a switch-mode power supply (smps) having a converter provided with a semiconductor switch for generating a converter output voltage across buffer capacitor means, and a control circuit for generating a control signal in dependence on the dimming signal Ds for controlling the semiconductor switch. According to the invention, the circuit is further provided with means for generating a converter output voltage-related signal Lvs for monitoring stable lamp operation by limiting the dimmed state by means of the control circuit. In conjunction with the converter output current, continuous lamp power control results in an improvement of the stable lamp operation over the full power range of the lamp.

Dependencies are inferred from the claim text.