TPS40090: Thermal compensation of DCR current sensing

Reto Christen

Part Number: TPS40090

Hi,

I am interested in implementing a thermal compensation of DCR current sensing.

This method is explained on page 17-19 in the data sheet. Unfortunately, I am stuck at point 4 and 5. How can I get a value for RTHE? What is exactly computed to get the example results RTHE1 and RTHE2?

I would appreciate if someone could help me out.

Thanks and best regards

Reto

over 7 years ago

0 Weidong Zhu over 7 years ago

TI__Expert 5965 points

You can use equation 20 to get RTHE1 and RTH2. Calculate Kdiv first using 2nd equation, then calculate RTH1 and RTH2 from 1st equation in equation 20.

Regards,
Weidong

0 Reto Christen over 7 years ago in reply to Weidong Zhu

Prodigy 80 points

Dear Weidong,

Thank you very much for your fast reply.

My calculations with the given example finish now with the same results.

Just one question for better understanding. When I measure DCR current without compensation (Fig. 10) then R should be calculated by using Equation (18). However, if I am compensating (Fig. 11) R is calculated as Equation(18)/KDIV. Is that correct or did I understand something wrong?

Thanks and best regards,

Reto

0 Weidong Zhu over 7 years ago in reply to Reto Christen

TI__Expert 5965 points

Hi Reto,

Yes, your understanding is correct. In this case, R=RE/KDIV(25) as described in step 3 on page 18.

Regards,
Weidong

0 Reto Christen over 7 years ago in reply to Weidong Zhu

Prodigy 80 points

Hi Weidong,

Okay, great to know.

Thank you very much for your replies, these were extremely helpful to me.

Best regards,

Reto

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TPS40090: Thermal compensation of DCR current sensing