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ADS131M02: internal clock

Koji Ikeda
Expert 5595 points
Part Number: ADS131M02

Hello Support team,

Customer inquires internal clock on AMDS131M02. Does ADS131M02 have internal clock? Or does it always require external CLKIN for the conversion?

Datasheet 8.4.6 Current-Detect Mode show " The device uses an internal oscillator that enables the device to capture the data without the use of the external clock input.". But, they can't find any other descriptions...

Thanks,

Koji Ikeda

  • +1
    TI__Mastermind 18900 points

    Hello Ikeda-san,

    This is a good question. Everything relating to modulation, data-rate, and conversion is related and derived from CLKIN so there is no internal clock.

    Current detect mode does use an internal clock, as mentioned in the datasheet. When active, it enables a clock so that the sampling rate is 2.7kSPS nominally and enables a block of circuitry that diverts the output of the digital filter to a comparator. The oscillator is crude and wouldn't be very good for the kind of accuracy that is expected for the typical use case of the device. However, if it just needs to trip the threshold of a comparator then it works well enough as a notification for something like anti-tamper detection. 

    If the customer has interest in an internal oscillator, please let us know. I imagine this isn't the first time we've heard the feedback and I know there will be a cost and accuracy trade-off. I found that most customers also want to ensure their clocks are synchronized if they want to maximize accuracy. More info can be found here: https://training.ti.com/delta-sigma-adcs-clocking . But if there's a use-case where "the ADC just needs to work" then might be a good case to add in an internal oscillator for typical use in the future.

    I would love to hear the customer's comments.

    Best,

    -Cole