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BQ501210: Rsense value

LS84
Prodigy 115 points
Part Number: BQ501210
Other Parts Discussed in Thread: BQ500100,

Hello,

We have developped a PCB using the development kit as an example. In the development kit the Rsense connected to the BQ500100 shunt amplifier is 15mOhms.

However, in the document BQ501210 datasheet (section 9.2.2.2) it recommends a 20mOhm resistor.

Which value should we use?

Thanks in advance and kind regards,

LS84

  • 0
    TI__Mastermind 23681 points
    dear LS84,

    in the end, it is up to you...
    indeed

    - the range of I_SENSE in BQ501210 is 0...2.5V
    - the gain of BQ500100 is fixed @ 50 +/-2%

    now if you use a too low Rsense the precision will be poor but the loss on that will be low; viceversa, with high Rsense the precision is better but the loss will be high...
    the best utilization of the range (=best precision) is achieved when

    Rsense x IMAX x 50 <= 2.5V

    that gives you the max Rsense to use...
    depending on application, the power rating of the Rsense might be a problem ($$ and size) so you might consider using a lower value...

    hope this helped a bit
    KR
    Vincenzo
  • 0 in reply to Vincenzo Pizzolante
    Prodigy 115 points

    Dear Vicenzo,

    Thanks a lot for your feedback.

    We'll make the calculation and test the new value.

    Kind regards,

    LS84