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BQ32000: Inquiry on Daily Drift Calculation for RTC BQ32000 with 32.768kHz Crystal

first_name last_name
Prodigy 10 points

Part Number: BQ32000

Tool/software:

Dear TI Support Team,

I hope this message finds you well.

I am currently evaluating the RTC BQ32000 models paired with a 32.768kHz crystal and would like to understand the expected daily time drift when using these components.

Could you please provide guidance or data regarding the daily drift rate for tBQ32000?

If additional details, such as the ppm accuracy range of the crystal or operating conditions, are required to determine the drift, kindly let me know.

Thank you very much for your assistance.

Best regards,

Max Tsai

  • 0
    TI__Guru** 116900 points

    Hi Max,

    the RTC is just a counter, it counts the crystal frequency and turns this information to time information. RTC itself has no drift, only the frequency source may drift. Drift here means the frequency of the crystal + built-in oscillator is not exactly equal to 32.768kHz. This is absolutely normal as any clock source's frequency has tolerance, so called ppm. 

    RTC usually has a capability to adjust the frequency so that the ppm error is very small, for example, a few ppm. 

    In BQ32000, the adjustable range is -63ppm to +126ppm. As long as the crystal's ppm is within this range, after adjustment, 0 ppm is possible.