CSD18514Q5A: Normalized On-State Resistance vs Temperature

Keith Keller

Expert 6260 points

Part Number: CSD18514Q5A

Hello,

We are designing with the CSD18514Q5A and had some questions on Figure 8 in the datasheet.

Should X-axis be Tc (case temp) or Tj (junction temp)?
Why is normalized Rds_on higher with Vgs=10V vs. Vgs=4.5V ? Shouldn’t it be the other way?

Thank you for your help. Keith

over 4 years ago

0 John Wallace1 over 4 years ago

TI__Mastermind 29535 points

Hi Keith,
Thanks for the questions.

1. It should be case temperature. The data for the characteristic curves in the datasheet is taken with case temperature.
2. I looked at data for a few devices and it is common for the on-state resistance temperature coefficient to be greater at higher VGS. Please note that the absolute value of rds(on) is still lower with VGS = 10V vs. VGS = 4.5V over temperature.

I'm going to close this thread. Please send me an email if you have additional questions.

0 Keith Keller over 4 years ago in reply to John Wallace1

TI__Expert 6260 points

Hello,

Regarding #1. There seems to be a bit of difference among MOSFET vendors. Some cite Tj and Ta as well as this example of Tc. Another indicated that this was a pulse test so as to not have self-heating issues and in this case, so that Tc and Tj can be thought of one in the same.

How specifically does TI test?

Thank you, Keith

0 John Wallace1 over 4 years ago in reply to Keith Keller

TI__Mastermind 29535 points

Hi Keith,
We do a pulse test in a temperature chamber so Ta, Tc and Tj are all essentially the same.

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CSD18514Q5A: Normalized On-State Resistance vs Temperature