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Yong
Level 2
Level 2
First like received 5 replies posted 10 sign-ins

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? 

Yong_2-1689141677775.png

  • 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?

Yong_3-1689141923507.png

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

 

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1 Solution
cynic_bandera
Employee
Employee
5 questions asked First question asked 100 sign-ins

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.

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3 Replies
cynic_bandera
Employee
Employee
5 questions asked First question asked 100 sign-ins

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.

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Hi Expert,

Thanks for your quick reply! 

For answer1, I think the curve is different when Id is different. Figure6 can prove that. 

BR,

Y

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Figure 6 shows saturation points at different gate voltages. But for constant Vgs it´s constant in the range up to saturation.

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