A new control IC for dimmable high-frequency electronic ballasts

A new control technique has been developed for the high-frequency dimming of fluorescent lamps using phase-sensing of the ballast output stage current to regulate lamp power. This approach has been incorporated into an IC giving the following ballast design implications: dimming to 1%; ignition at any dim setting; multiple lamp management; no heating or current transformers required; No opamps required; immunity from lamp negative incremental impedance effects; reduction of PCB interconnects, IC pin count and components; minimum changes needed to adapt non-dimming ballast for dimming; and end-of-life detection (nondimming). The result is a high-performance lighting solution for dimmable ballasts and ballasts with end-of-life protection at a significant cost reduction. A complete linear dimmable ballast has been built that incorporates the new IR2159 IC verifying all of these features. The end-of-life feature can only be applied to a nondimming ballast (using the IR2158 IC) and details of this are covered.