December 2009

Doc ID 15679 Rev 1

1/32

AN2983

Application note

Constant current inverse buck LED driver using L6562A

Introduction

Whenever a lighting application, such as street lighting for example, requires an elevated

number of LEDs, there are basically two solutions: the first is to connect all the diodes in

series in a single "string"; the second is to place several strings in parallel with fewer

elements in each one.

The first solution, even if simpler, poses stringent safety requirements due to the high supply

voltage. The latter needs a lower input voltage but the current through each string has to be

independently controlled.

Since, from a system point of view, the second solution seems more viable, we have

developed an application to investigate the possibility of employing an L6562A to implement

such a constant current controller. This document describes the EVL6562A-LED

demonstration board and summarizes the relevant results obtained.

Figure 1.

EVL6562A-LED: L6562A constant current inverse buck driver module

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