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TPS25830-Q1: R_ILIMIT calculation

Youhei Miyaoka
Intellectual 2805 points
Part Number: TPS25830-Q1

Tool/software:

Hi team,

Could you teach me how to calculate eq(7) about R_ILIMIT.

Are these three parameter (R_SET, R_SNS, I_LIMIT) should use typical value?

Regards,

Youhei MIYAOKA

  • +1
    TI__Mastermind 43185 points

    Hello Youhei,

    Yes, 15mΩ for R_sns and 300Ω for R_set are the recommended values to be used for the TPS25830-Q1. Therefore, these values should also be used for Equation 7.

    If the desired current limit is 3.3A, for example, Equation 7 yields 11.9kΩ. 

    Hope this helps,

    Seong

  • 0
    Prodigy 10 points

    Hello Seong san

    Assume, current limit is 3.3A, I would like to know how much margin of error should I consider?
    does it depend on Resistors (R_ILIMIT, R_SET, R_SNS)?
    or is there any determined current range for current limit?

  • 0 in reply to ?? ??
    TI__Mastermind 43185 points

    Hello,

    Yes, the accuracy of the current sense  is dependent on the R_ilimit, R_set, and R_sns resistor parameters such as tolerance, temperature coefficient, resistor composition, and operating temperature. The goal is to minimize the variance of the resistance, especially at high ambient operating temperatures.

    Also, short parallel traces from the CSP and CSN traces to the shunt resistor will yield the best performance. A small filter capacitor in parallel with R_sns and a small filter capacitor from CSN/OUT to AGND can also help decouple noise.

    Hope this helps,

    Seong