AN2649 Datasheet, PDF (1/20 Pages) STMicroelectronics – The electrical and thermal performances of switching converters are strongly

AN2649
Application note
A power factor corrector with MDmesh^TM II and SiC diode
Introduction
The electrical and thermal performances of switching converters are strongly influenced by
the behavior of the switching devices. Modern power devices design requires a trade-off in
terms of forward voltage drop, breakdown voltage and switching speed. In AC-DC
converters such as PFC circuits, efficiency is strongly related to the switch performances
and the diode recovery behavior (please refer to 1 in Bibliography on page 18). In the past
the benefits of the improved MOSFET performances have been generally spoiled by the
diode current recovery behavior. In recent years the introduction of the Silicon Carbide (SiC)
Schottky diode has led to an effective advantage in the switching transient losses reduction,
thanks to the very low reverse recovery current with respect to the traditional fast diode. The
impact on the converter of the improved characteristics of both devices leads to an increase
in efficiency.
In this application note the new generation of super-junction MOSFET (MDmesh^TM II) and
SiC diodes has been used to design a 200 W continuous PFC converter. The dynamic
characteristics of both super-junction MOSFET and SiC diodes, are investigated in the
actual application and compared with the traditional components in order to carry out the
qualitative and quantitative improvements in terms of switching performances and converter
efficiency. The presented experimental results allow analysis of information for the converter
designers focusing on the determination of benefits and effectiveness of the devices utilized
in the considered application.
September 2008
Rev 2
1/20
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