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DRV8412 & DRV8842 ON resistance of FET

Atsushi Yamauchi
Genius 4810 points
Other Parts Discussed in Thread: DRV8412, DRV8842

I have a question of ON resistance of FET of DRV8412 and DRV8842.

There is the specification of ON resistance of LS and HS FET.

But the customer want to know them with below condition.

1. GVDD=13.5V, Tj=150degreeC

2. GVDD=16V, Tj=150degreeC

So, I want to know the relevance of the resistance and GVDD, Tj and so on to estimate the resistance.

Could you please advise to me?

Best regards,

Atsushi Yamauchi

  • 0
    TI__Guru 55605 points

    Yamauchi-san,

    First of all, GVDD > 13.2V is beyond out recommended operating conditions for the DRV8412. 

    We do have a curve that can help answer these questions for a GVDD within the recommended operation range of the device.  This is shown in Figure 3 for GVDD = 12V.  A plot is given showing a scale factor that can be used to multiply by the given Rdson at 25C.  We stop at 125C, but you can extrapolate to 150C and the scale factor is approximately 1.6x the Rdson given in the datasheet.

    For the DRV8842, it is not possible to adjust GVDD.  Two numbers are given for Rdson.  One at 25C and one at 85C.  From those two numbers, you can see that the scale factor is 1.3 over 60 degrees C delta.  It is a linear relationship and basically matches that of the DRV8412. 

    So, in both cases, I would give 1.6x as the scale factor from the 25C numbers for Rdson given in the datasheet to the 150C number.