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May 2008 Rev 1 1/44
AN2747
Application note
250 W HID metal halide electronic ballast
Introduction
This application note describes the two stages of electronic ballast for a 250 W HID metal
halide lamp. The ballast is composed of a boost converter (power factor controller PFC)
working in fixed OFF time and an inverter composed of a full bridge that drives the lamp at
low frequency square wave.
This design was realized thanks to the very large STMicroelectronics product portfolio. The
components include a PFC driver, half-bridge drivers, a microcontroller, an auxiliary power
supply, a voltage reference, logic parts, an amplifier, comparators, power devices as Power
MOSFETs, IGBTs, and fast diodes.
In the present note special attention has been given to the full bridge stage. The tests have
been conducted using a 250 W metal halide lamp HQI - T (OSRAM) and some design
criteria are given with test results. In the full bridge section all lamp phases have been
analyzed.
Figure 1. STEVAL-ILH001V1
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