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TPS43350-Q1: Current sense resistor is unused

tateo yamashiro
Guru 10890 points
Part Number: TPS43350-Q1

Hi,

We got a question from the customer about TPS43350-Q1.
Could you help us?

[Question]
If they won't use the current limit function, can the IC remove the current sense resistor? I assume they should use this resistor because the slope compensation function needs it. But please let me confirm this question.

Best Regards,
tateo

  • 0
    TI__Genius 9655 points
    Yamashiro-san,
    you are correct, the current sense resistors are required, for the slope compensation but also for the general buck-functionality, since those are current-mode bucks.
    If they want to save the resistor (or the ohmic losses of it), they may use DCR-sensing, using the ohmic resistance of the inductor (see 7.3.1.6 in datasheet). However, since the DCR has a large tolerance and drifts with temperture, the current limit is rather wide and thus the inductor and FETs need to be chosen to accomodate the worst case current that the DCR-dependent current limit may reach.
    Best regards,
    Frank