Patent ID: 7911154

Claim:
An electronic ballast with a converter in the form of a step-up converter for selectively operating a discharge lamp directly on a system supply or using a phase gating dimmer, said electronic ballast comprising at least one differentiator, which is connected between a system line and a reference potential of the electronic ballast, so that jumps in the supply voltage are output by said at least one differentiator and are passed on to a controller of the electronic ballast, the controller being constructed in such a way that the controller distinguishes between operating said discharge lamp using said phase gating dimmer and operating the discharge lamp directly on said system supply, wherein said controller is configured to control said step-up converter so that during operation of the discharge lamp directly on said system supply, and in response to a detection of operation on said system supply by said controller, said step-up converter has a lower switch-off current threshold value than during operation of the discharge lamp using said phase gating dimmer, and wherein said step-up converter, during said direct operation on the system supply, draws a current from said system supply which has a lower amplitude than during operation using said phase gating dimmer.