August 2011

Doc ID 018857 Rev 1

1/25

AN3407

Application note

Resonant driver for LED SMPS demonstration board

based on the L6585DE

Introduction

This application note describes the performance of a 100 W LED switched-mode power

supply (SMPS). The L6585DE embeds a high-performance transition mode (TM) power

factor correction (PFC) controller, half-bridge (HB) controller and all the relevant drivers

necessary to build a combo IC. The L6585DE embeds a wide range of features to provide

an energy-saving and cost-effective solution for the LED SMPS demonstration board

(STEVAL-ILL038V1).

Previous dedicated ICs for LED SMPS applications allowed designers to achieve good

driver efficiency. The PFC section has superior performance in terms of harmonic content

mitigation. High power factor (PF) and total harmonic distortion (THD) reduction are

obtained as required by international norms, especially concerning universal input voltage

operations. The TM PFC operation and high-efficiency performance of the half-bridge

topology provide very good overall circuit efficiency.

Film capacitors are one of the most popular types of discrete components. They generally

offer excellent electrical properties and are advantageous in high current and high

temperature conditions. For these reasons, film capacitors are used in LED SMPS

applications. In order to guarantee maintenance-free operation required by these types of

applications during the useful lifetime of the LED, electrolytic capacitors have been replaced

by film capacitors in the STEVAL-ILL038V1 board.

Other features, such as half-bridge overcurrent with frequency increase and PFC

overvoltage, allow designers to build a reliable, flexible solution with a reduced component

count.

Figure 1.

STEVAL-ILL038V1 demonstration board

www.st.com