IXDN0036 datasheet(4/41 Pages) IXYS

4 / 41 page

Introduction

1-2

ATAVRFBKIT / EVLD001 User Guide

7597A–AVR–02/06

Figure 1-1. Fluorescent Tube Composition

Since the argon conductivity increases and resistance across the lamp ends decreases

as the gas becomes excited, an inductance (ballast) must be used to limit and control

the gas current. In the past, an inductor could be designed to limit the current for a nar-

row range of power voltage and frequency. A better method to control gas current is to

vary an inductor’s volt-seconds to achieve the desired lamp current and intensity. A vari-

able frequency inverter operating from a DC bus can do this. If the inductor is part of an

R-L-C circuit, rapid start ignition currents, maximum intensity, and dimming currents are

easily controlled depending on the driving frequency versus resonant frequency.

A ballast should include a power factor corrector (PFC) to keep the main current and

voltage in phase with a very low distortion over a wide range of 90 to 265 VAC 50/60 Hz.

With microcontroller control, economical remote analog or digital control of lamp func-

tion and fault reporting are a reality. Moreover, adjusting the lamp power to correspond

with human perceived light level is possible. An application specific microcontroller

brings the designer the flexibility to increase performance and add features to his light-

ing product. Some of the possible features are described in detail below. The final

design topology is shown in the block diagram of figure 3.

Now, a new way of dimming fluorescent lamps fills the incandescent/fluorescent feature

gap plus adds many additional desirable features at a very reasonable cost.

IXDN0036 Datasheet(PDF) 4 Page - IXYS Corporation