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Original question:

BQ20Z655-R1: Qmax Update Voltage Condition

BQ20Z655-R1: Accuracy of 5 hour timer

Justin Andrews
Prodigy 100 points
Part Number: BQ20Z655-R1

In sluu493a section 2.4.3.2 it says that if 5 hours has exceeded a OCV reading is taken even if the dV/dt condition is not satisified.

I don't see any timing tolerances/accuracy in the parts datasheet.   What should i expect for the accuracy of this 5 hour timer?

-Justin

  • 0
    TI__Guru* 76230 points
    Hi Justin
    The gauge has an internal clock which is pretty accurate. The rest period should be set to 5 hour and extra 5 mins to give some wiggle room

    thanks
    Onyx
  • 0 in reply to Onyx Ahiakwo
    Prodigy 100 points
    I guess i was expecting a more technical answer.
  • 0 in reply to Justin Andrews
    TI__Genius 16700 points
    Justin,

    the internal clock has a maximum tolerance of 3% for the high frequency oscillator and 2.5% for the low frequency oscillator. Those are the maximum deviations that will occur to small portion of population of parts under extreme operating conditions. The typical value for both oscillators is 0.25%. You should expect to see that 0.25% number for the majority of the population of parts (average plus and minus one standard deviation), operating between 0 and 70°C. Based on that information, the 5-hour period should typically vary ±45 seconds, but could potentially be ±9 minutes.

    We do not characterize the dv/dt value and therefore cannot establish a specific tolerance for it.

    Let me know if that answers your question!