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MOSFET (Si/SiC) Forum Discussions

User13734
Level 1
First question asked
Level 1
We widely use simulation with Infineon MOSFET models as they are very accurate. We are using Simetrix/SIMPLIS simulator.
But recently I found* a very strange behaviour of MOSFET Rdson at the simulation.
As an example I used BSC028N06NS. If drain current is statics (DC), simulation perfectly match datasheet (see Fig1 and Fig2).
But , if drain current changes, Rdson changes very much. Fig3 shows sinusoidal
Current applied to MOSFET drain, while gate is kept at 12V DC voltage.
As can be seen from this picture, at the beginning of the wave when current is
small, Rdson is much higher than nominal value and it is dropping.
At the top of sinusoidal wave Rdson stays relatively constant. When drain current
starts dropping , Rdson drops and even becomes negative!
Fig4 Shows Rdson behaviour for triangle shape of drain current
Fig5 shows Rdson behaviour for triangle shape of drain current, but for much
lower frequency. In this case Rdson changes is much less, than shown on Fig4.
Could you, please explain this behaviour.
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1 Solution
srhim1971
Employee
10 replies posted 5 replies posted First question asked
Employee
RDS on depends on a lot of factors,e.g. VGS,ID,Temperature,etc)
For the simulation of the device we recommend to check the simulation parameters.

See here: https://www.infineon.com/dgdl/Infineon-ApplicationNote_PowerMOSFET_SimulationModels-AN-v01_00-EN.pdf...

- Which model did you use? Refer to chapter 3.
- The Simetix simulation parameters are described in chapter 6.1. Did you use these?
- Which temperature did you use?

You must make sure that the device is in the static region which is why you need to wait until the MOSFET is switched on before measuring.

View solution in original post

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1 Reply
srhim1971
Employee
10 replies posted 5 replies posted First question asked
Employee
RDS on depends on a lot of factors,e.g. VGS,ID,Temperature,etc)
For the simulation of the device we recommend to check the simulation parameters.

See here: https://www.infineon.com/dgdl/Infineon-ApplicationNote_PowerMOSFET_SimulationModels-AN-v01_00-EN.pdf...

- Which model did you use? Refer to chapter 3.
- The Simetix simulation parameters are described in chapter 6.1. Did you use these?
- Which temperature did you use?

You must make sure that the device is in the static region which is why you need to wait until the MOSFET is switched on before measuring.
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