SiC Power Device｜Application
Differences in Surge Occurrence Depending on Package
2024.10.23
Points of this article
・Surges that occur between the drain and source of a SiC MOSFET are different depending on the package type.
・Compared with the TO-247N package, the TO-247-4L enables faster switching due to modification of the driving circuit path, and consequently surges tend to be larger.
As one matter to be aware of related to design, this article explains how turn-off surges occurring across the drain and source of a SiC MOSFET differ depending on the device package.
- Surges occurring between drain and source
- Types and selection of snubber circuits
- C snubber circuit design
- RC snubber circuit design
- Discharge RCD snubber circuit design
- Non-discharge RCD snubber circuit design
- Difference in surge occurrence depending on package
SiC MOSFET: Differences in Surge Occurrence depending on Package
Here an example of different surge occurrences for different SiC MOSFET packages is introduced.
Fig. 11 shows representative SiC MOSFET packages. Here (a) is a widely-used generic TO-247N (three-pin) package, while (b) is a TO-247-4L (four-pin) package, use of which has been increasing in recent years, provided with a source pin for the driving circuit (a so-called Kelvin connection).
Compared with the TO-247N in (a), the TO-247-4L in (b) is a package with switching speeds made faster through changes to the driving circuit path. For this reason, turn-on surges and turn-off surges tend to be greater than for devices in the package of (a).
Fig. 12 compares turn-off surge waveforms for products in these two packages. The measurement circuit used was the same as in (a) of Fig. 9 in “Non-Discharge RCD Snubber Circuit Design“. Whereas the drain-source surge in the turn-off waveform at VDS=800 V, RG_EXT=3.3 Ω, ID=65 A was 957 V for the TO-247N package in (a) (3L, blue line), the surge for the TO-247-4L package in (b) (4L, red line) was larger, at 1210 V.
This ringing in VDS due to the surge occurs because current flows through CDG and CGS as well as through CDS, as shown in Fig. 8 in “Non-Discharge RCD Snubber Circuit Design“, so that an unanticipated surge may occur in the MOSFET gate-source voltage VGS, possibly exceeding the VGS surge rating. Methods for suppression of VGS surges are explained in some detail in “SiC MOSFETs: Methods for Suppressing Gate-Source Voltage Surges” in the Basic Knowledge area of Tech Web, as well as in a separate Application Note (*2). When such countermeasures are by themselves inadequate for surge suppression, adding a snubber circuit between drain and source may prove effective for surge suppression.
*2: Application Note on “Gate-Source Voltage Surge Suppression Methods” (No. 62AN009J Rev. 002), ROHM Co., Ltd., April 2020
【Download Documents】 Basics of SiC Power Devices
This handbook explains the physical properties and advantages of SiC, the differences in characteristics and usage of SiC Schottky barrier diodes and SiC MOSFETs with a comparison to Si devices, and includes a description of full SiC modules with various advantages.
SiC Power Device
Basic
- What are SiC Schottky barrier diodes? ? Introduction
- What are SiC-MOSFETs? – SiC-MOSFET Features
- What are Full-SiC Power Modules?
- Summary
- Introduction
- What is silicon carbide?
Application
-
Introduction
- SiC MOSFET Bridge Configuration
- SiC MOSFET Gate Driving Circuit and Turn-On/Turn-Off Operation
- Currents and Voltages Occurring Due to Switching in Bridge Circuits
- Behavior of the Gate-Source Voltage During Low-side Switch Turn-on
- Behavior of the Gate-Source Voltage During Low-side Switch Turn-off
- Summary
- SiC MOSFETs: Method for Determining Losses from Switching Waveforms
-
SiC MOSFETs： Snubber Circuit Designs ーIntroductionー
- Non-Discharge RCD Snubber Circuit Design
- Surges Occurring between Drain and Source
- Types and Selection of Snubber Circuits
- C Snubber Circuit Design
- RC Snubber Circuit Design
- Discharge RCD Snubber Circuit Design
- Non-Discharge RCD Snubber Circuit Design
- Differences in Surge Occurrence Depending on Package
- SiC MOSFETs： Snubber Circuit Designs ーSummaryー
- Points to Note When Measuring SiC MOSFET Gate-Source Voltages: General Measurement Methods
-
Conventional MOSFET Driving Method
- Packages Provided with Driver Source Terminals
- Differences Made by and Benefits of a Driver Source Pin
- Benefits of a Driver Source Terminal: Comparisons Using Double Pulse Tests
- Behavior of Gate-Source Voltages when in a Bridge Configuration: Behavior at Turn-on
- Behavior of Gate-Source Voltages when in a Bridge Configuration: Behavior at Turn-off
- Points to be Noted Relating to Board Wiring Layout Key Points of This Article
- Verification of Loss Reduction Using Latest-Generation SiC MOSFETs
- About Surges in Gate-Source Voltages
Product Information
- SiC Schottky Barrier Diodes
- SiC MOSFET
- SiC Power Modules
- SiC Schottky barrier diode Bare Die
- SiC MOSFET Bare Die
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