September 2012

Doc ID 16774 Rev 2

1/30

AN3105

Application note

48 V - 130 W high efficiency converter with PFC for LED street

lighting applications - European version

By Claudio Spini

Introduction

Nowadays, LEDs are becoming ever more popular, thanks to their particular characteristics,

such as high efficiency and long life, and therefore they are pushing the innovation of current

lamp types and strongly contributing to reducing the energy consumption for internal or

external lighting. This is also the case in street lighting applications, where higher efficiency

and long life are vital for reducing costs.

For these reasons a street lighting power supply designed to power an LED lamp must have

high efficiency and at least a similar lifetime, in order to guarantee the maintenance free

operation required by these kinds of applications.

This application note describes the characteristics and features of a 130 W demonstration

board (EVL130W-SL-EU), tailored on an LED power supply specification for street lighting.

The circuit is composed of two stages; a front-end PFC using the L6562AT and an LLC

resonant converter based on the L6599AT.

The peculiarities of this design are; very high efficiency, extended European input mains

Because reliability (MTBF - “Mean Time Between Failures”) in power supplies is typically

affected by electrolytic capacitors and their typical high failure rate, unless using very

expensive types, this board offers a very innovative design approach as the board doesn't

implement any electrolytic capacitors, which are replaced by film capacitors from EPCOS.

Component de-rating has also been carefully applied during the design phase, decreasing

the component stress as recommended by MIL-HDBK-217D. The number of components,

thanks to the use of the new L6562AT and L6599AT devices, has also been minimized,

therefore increasing the MTBF and optimizing the total component cost. Thanks to the high

efficiency achieved no heatsinks are required. The resonant stage power components are

SMT, like most of the passive components, therefore decreasing production costs.

The board also has protections in case of overload or short-circuit, open-loop by each stage,

or input overvoltage. Because of the particular application, all protections, in the case of

intervention, are auto-restart.

Figure 1.

EVL130W-SL-EU: 130 W SMPS for LED street lighting applications

www.st.com