Universal retrofit LED lamp for fluorescent lighting fixture with start-up process emulator

A light-emitting-diode (LED) lamp driver with its input compatible with high- and low-frequency sources is proposed. It can be powered by the ac mains, low-frequency electromagnetic ballast, or high-frequency electronic ballast. Its input impedance is controlled to meet the operational requirements and conditions of different sources and its output is controlled to deliver the required power to the LED array. However, in condition electronic ballast is connected, due to the self-protection functions of some electronic ballast, the start-up transient of a gas discharge lamp is necessary to be emulated. The driver has a startup mechanism that emulates the ignition process of a fluorescent lamp. Such a wide source compatibility of the driver enables the lamp be applied in new lighting installations or retrofitting fluorescent lamps with LED lamps without modification of existing ballasts and/or lighting infrastructure. A 20W prototype, which is designed to retrofit a 36W T8 fluorescent lamp, has been built and evaluated with different sources.