Using Kelvin Connections to enhance switching efficiency in SiC FETs

Focus:

This four-page article describes the impact of common-source lead inductance on the gate bias and switching of wide-bandgap power transistors, how the addition of a Kelvin connection to SiC power devices alleviates this problem, and gate-drive considerations for power supply designers. The article begins by explaining how internal bond wires and package leads (such as in the TO-247) add common-source inductance in FETs, which generate transients that can slow down the turn-off and turn-on of the transistors, particularly fast-switching wide-bandgap devices. The difficulty of using negative gate drive to counter the problem is discussed and the benefits of adding a Kelvin connection to TO-247 packaged SiC JFET cascodes is explained along with guidance on how to use these devices in circuits.

What you’ll learn:

• How to apply SiC JFET cascodes with Kelvin connections
• How to reduce switching losses and gate ringing in SiC power devices by using Kelvin connections
• How to understand the impact of lead inductance on gate bias and switching in wide-bandgap power devices

View the Source

Author & Publication:

Dr. Anup Bhalla, VP Engineering at United SiC, Vendor website, Nov 12 2018

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