A sensing and regulation concept for high end dimming ballasts

A regulation topology is introduced where the discharge current of fluorescent lamps is used to improve dimming performance under harder requirements. An accurate detection of lamp ignition and a fast regulation lead to a start without visible light flash even at low dim levels. With a digital controllable characteristic of the lamp current regulator it is possible to dim without any flicker in a wide ambient temperature range. Finally a simple active current measurement compensates the parasitic reactive current, caused by lamp wiring. The sensing and regulation concept is focussed on ignition and dimming but fits also other needs like lamp failure detection and automatic restart at lamp change.