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May 2013 DocID024196 Rev 1 1/26
AN4242
Application note
New generation of 650 V SiC diodes
Introduction
For many years ST has been a worldwide leader in high voltage rectifiers dedicated to
energy conversion. During the last decade, electronic systems have followed a continuous
trend towards higher power density and more energy savings driven by governments’
environmental awareness. Power-supply designers are permanently confronted with
stringent efficiency regulations (Energy Star, 80Plus, European Efficiency…). They are
forced to consider the use of new power converter topologies and more efficient electronic
components such as high-voltage silicon-carbide (SiC) Schottky rectifiers. To help them face
this challenge, ST developed in 2008 a first family of 600 V SiC diodes. After having sold
millions of pieces, ST’s reliability and know-how is confirmed on these new components
using wide band gap materials.
In hard-switching applications such as high end server and telecom power supplies, SiC
Schottky diodes show significant power losses reduction and are commonly used. A
growing use of those rectifiers is also recorded in solar inverters, motor drives, USP and
HEV applications.
However, the high cost of this technology tends to drive designers to use it at high
current-density levels (3 to 5 times higher than standard Si diodes), inducing more
constraints on the diode. Indeed, the Silicon-carbide material features a positive thermal
coefficient potentially leading to some instability and lower current-surge robustness than
silicon diodes. ST decided to review the design and develop a second generation of SiC
diodes offering an enhanced current capability while still featuring an attractive switching-off
behavior. The peak reverse voltage was also increased to 650 V in order to ensure a safer
operation in certain designs.
Typical applications (non-exhaustive list)
Charging station
ATX power supply
AC/DC power management unit, high voltage, and other topologies
Desktop and PC power supply
Server power supply
Uninterruptible power supply
Photovoltaic string and central inverter architecture
Photovoltaic power optimizer architecture
Photovoltaic microinverter grid-connected architecture
Photovoltaic off-grid architecture
Telecom power
www.st.com
