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TPS65910: RTC without external oscillator / crystal?

Part Number: TPS65910

When using the internal RC oscillator, the RTC in the PMIC appears to loose 1-2 seconds every few minutes; The output frequency is 32.0kHz as expected per the datasheet.

After installing the 32.786kHz external crystal, and clearing the CK32K_CTRL bit, the time is spot on.

After reading the datasheet and forums, can I get a definitive answer to:

Is there a way to run the RTC off the internal oscillator without gross inaccuracies?

Is there a way to base it on the 32.0kHz internally generated clock?

Does it REQUIRE a 32.786kHz external crystal in order to be of any usefulness?

Thanks,

--Luke Suchocki

  • HI Luke,

    The internal 32k oscillator is used for internal timing (power on sequence for example), it's not intended to provide accurate RTC timing. It will not be able to generate higher accuracy signal.

    The crystal is required for RTC to provide accurate time. OTPs with crystal not required typically just provide a voltage and allow the processors to maintain it's own RTC (depends on the processor).