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