ELECTRONIC BALLAST HAVING A BOOST CONVERTER WITH AN IMPROVEDRANGE OF OUTPUT POWER

摘要

A boost converter for an electronic dimming ballast for driving a gas dis charge lamp has an increased output power range. The boost converter operate s in discontinuous conduction mode when a desired intensity of the lamp is b elow a first threshold intensity, and operates in critical conduction mode w hen the desired intensity is above a second threshold intensity. The boost c onverter comprises a delay circuit for introducing an amount of delay into t he conduction of current through the boost converter. A control circuit of t he ballast is operable to drive the delay circuit and thus control the opera tion of the boost converter in response to the desired intensity of the lamp . The control circuit is further operable to drive the delay circuit with a pulse-width modulated signal to provide multiple amounts of delay into the o peration of the boost converter.