ELECTRONIC BALLAST HAVING A BOOST CONVERTER WITH AN IMPROVED RANGE OF OUTPUT POWER

摘要

A boost converter for an electronic dimming ballast for driving a gas discharge lamp has an increased output power range. The boost converter operates in discontinuous conduction mode when a desired intensity of the lamp is below a first threshold intensity, and operates in critical conduction mode when the desired intensity is above a second threshold intensity. The boost converter comprises a delay circuit for introducing an amount of delay into the conduction of current through the boost converter. A control circuit of the ballast is operable to drive the delay circuit and thus control the operation 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 operation of the boost converter.