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bq76920: Lowest practical sense resistor value?

John M
Expert 2135 points
Other Parts Discussed in Thread: BQ76920, BQ76930

Hello,

We have an application for the bq76920 and bq76930. The discharge current level varies from about 5A - 35A  (continuous) with pulses of up to 200A for one second and up to 400A for 20-40 milliseconds. Charge current varies from 1A to 50A.

Can these chips operate well with a 0.5 milliohm sense resistor? It would make setting the OCD and SCD fault thresholds and timing much easier and we wouldn't exceed the recommended voltage range for SRP/SRN.

JohnM

  • 0
    TI__Guru 54715 points

    The device responds to voltage, so a sense resistor appropriate for the load is OK.  With the smaller resistor the part will not be able to resolve as small of currents, at low enough current the signal disappears into the CC noise.

  • 0 in reply to WM5295
    Expert 2135 points

    We were thinking that would be what happened, thank you!

    Initially, we won't be doing any coulomb counting for this application and the lowest current flow will be about 5A. If we add coulomb counting as a feature later on, hopefully thus current level will be above the noise floor. We'll do lots of testing to find out.

    JohnM