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# MOSFET parameter discussion

Level 2
Level 2

Hi Expert,

Regarding MOSFET Rds_on parameter, I have several confusion and would like to consult you.

Below questions are general questions, but for better description I will take IPD50N04S3-09 as an example.

1. Below figure shows Rds_on ~Tj. The test condition is under Id=50A. My question is, how will the curve change if we change Id to another value, such as 10A, 20A or 30A? Will the trend still be the same?
2. If I want to use a function to approximate below curve, what kind of function do you recommend, first order, second order or third order?

• Below figure show the Rds_on ~Id. I would like to know, if the Tj remains constant while testing? If YES, could you please tell how you keep Tj constant?

All in all, is there a possible way that we can knwo MOSFET Rds_on under any Id and Tj with a mathematic way? Thanks.

BR,

Y

1 Solution

# Re: MOSFET parameter discussion

Employee
Employee

1. The curve and the trend are constant with different current.

2. There are some tools (you can google it) which can digitize your curve and create a formula. For every MOSFET type it will be different. You can approximate it with the first order in your real operation range.

3. The curve is taken with a constant temperature by short pulses, which helps to keep Tj const.

3 Replies

# Re: MOSFET parameter discussion

Employee
Employee

1. The curve and the trend are constant with different current.

2. There are some tools (you can google it) which can digitize your curve and create a formula. For every MOSFET type it will be different. You can approximate it with the first order in your real operation range.

3. The curve is taken with a constant temperature by short pulses, which helps to keep Tj const.

Level 2
Level 2

Hi Expert,