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ADS124S06: External Clock to ADS124S06

Rinaldo Miranda
Prodigy 20 points
Part Number: ADS124S06

Dear

What type of component should I use as an external clock on the ADS124S06? Can I use a crystal or is a temperature compensated oscillator necessary?

Would it be possible to point me to an oscillator or crystal with greater precision?

Thanks

Rinaldo

  • 0
    TI__Guru** 112725 points

    Hi Rinaldo,

    Welcome to the E2E forum!  The ADS124S06 is designed to work well with the internal oscillator.  The only reason you would want to use an external oscillator is to improve the operation over that of the internal oscillator with respect to the filter notches or to adjust the filter notch position.  You cannot use a standard crystal, but instead an oscillator with the desired frequency.  The nominal frequency would be 4.096MHz.

    The choice of the oscillator will depend on the operating voltage and desired frequency stability.  There are many possible oscillators to choose from, so it is difficult for me to recommend one over another.  I compare stability (25ppm is better than 100ppm), clock jitter (low jitter is best), price and physical size.  I have had good experience in the past using Crystek, C3391-4.096, but there are other similar performing crystal oscillators from Abracon, CTS, Citizen, ECS, etc..

    Best regards,

    Bob B

  • 0 in reply to Bob Benjamin
    Prodigy 20 points

    Hi Bob,

    Thanks for the feedback.
    But I have another question:
    How can I know the maximum error in Effective Resolution (Bits) due to the variation of the internal oscillator (+ - 1.5%)?

    I'm waiting,

    Best regards,

    Rinaldo

  • 0 in reply to Rinaldo Miranda
    TI__Guru** 112725 points

    Hi Rinaldo,

    I'm not sure what your true concern is with respect to an error using the internal oscillator.  The ADS124S06 is designed to use the internal oscillator.  You will not see an error with respect to using the internal oscillator in the conversion result.  What you may see is the output data rate shifting by as much as +/-1.5% which is the min/max spec of the internal oscillator.

    You will also see the filter notch deviate by a similar percentage, but this will not add error in the conversion result.  You may see some additional noise if you are dependent on the filter notch such as for 50/60 Hz filtering at the lower data rates.  Keep in mind that power line-cycle frequency can also deviate, so even with an external oscillator you may pick up line-cycle noise.

    Best regards,

    Bob B