下载
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
range (177-277 V
AC
) operation, and long term reliability.
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
