Patent ID: 7768215
Filing Date: 2010-08-03
Classification: H05B

Abstract:
1. An electronic ballast for a gas discharge lamp comprising: a power converter circuit comprising a buck inductor; a rectifier circuit coupled to the power converter circuit to provide a rectified buck inductor signal corresponding to current in the buck inductor; a monitoring circuit defining an activation range and coupled to the rectifier circuit to provide a monitoring circuit signal when the rectified buck inductor signal is in the activation range; a reference signal generator operable to provide a reference signal; a comparing circuit coupled to the rectifier circuit, to the monitoring circuit, and to the reference signal generator to receive the rectified buck inductor signal, the monitoring circuit signal, when present, and the reference signal; the comparing circuit being operable to provide a comparing circuit output signal that is modulated by comparisons between the reference signal and a combination of the rectified buck inductor signal and, when present, the monitoring circuit signal; and the power converter circuit further comprising an input coupled to receive the comparing circuit output signal, the power converter circuit being responsive to the comparing circuit output signal to control the current in the buck inductor.