SiC Power Device｜Application
Differences Made by and Benefits of a Driver Source Pin
2024.02.21
Points of this article
・By providing a driver source terminal, the influence of VLSOURCE on VGS_INT can be eliminated.
・As a result, the turn-on time can be improved.
In the first article, the voltage during switching operation of a MOSFET in a conventional package (hereafter a “conventional MOSFET”) not having a driver source terminal was explained, as background for an explanation of the effect of a driver source terminal. In this article, the operation of a MOSFET provided with a driver source terminal, as well as the benefits of the driver source terminal, are explained.
Differences Made by and Benefits of a Driver Source Pin
The diagram on the lower left shows the driving circuit of a conventional MOSFET, and that on the lower right is the driving circuit of a MOSFET provided with a driver source terminal. The difference is the return line connection in the driving circuit; in the conventional MOSFET, it is connected to the source terminal, whereas in the MOSFET with the driver source terminal it is connected to the driver source terminal, while the source is connected to a separate power source terminal. The blue arrows indicate voltages during switching operation.
The voltages during switching operation occur in the same way in both cases, as indicated by the blue arrows. To reiterate, when VG is applied and the MOSFET turns on, ID increases, and a voltage VLSOURCE appears across LSOURCE in the direction (I) in the diagram. Because the current IG flows into the gate terminal, a voltage drop VRG_EXT (I) occurs across RG_EXT.
In this way, the voltages that occur are the same, but in the case of the conventional MOSFET, VLSOURCE and VRG_EXT (I) are included in the driving circuitry during turn-on, and so the chip voltage VGS_INT necessary for the MOSFET turn-on operation is reduced, and consequently the turn-on speed tends to be reduced. In contrast, when a driver source terminal is provided, ID flows to the power source terminal and not the driver source terminal and is not included in the driving circuitry, and therefore the effect of VLSOURCE on VGS_INT can be eliminated. This is expressed in equations as follows.
When a driver source pin is provided, the term 
(=VLSOURCE ) can be eliminated, and so we see that this voltage does not affect VGS_INT. This is the effect of the driver source terminal, and as a consequence the turn-on speed can be improved.
The next article will consider the effect of the driver source terminal in terms of operation waveforms.
【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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