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ADS1274: Sync signal

Eric Boler
Prodigy 105 points
Part Number: ADS1274
Other Parts Discussed in Thread: ADS1278, ADS1271

We are contemplating the use of the ADS1274 and are curious about the SYNC signal.  The system would have several converters which we want to keep synchronized over long periods of time.  Is the SYNC pin only used at startup or can a continuous periodic signal be applied to the pin to ensure all ADCs remain synchronized?  I assume the same answer applies to both the ADS1278 and the ADS1271.

Thanks

Eric 

  • 0
    TI__Guru**** 181521 points
    Hi Eric,

    Generally speaking the SYNC pin of the ADS1274 or ADS1278 is used at startup only to synchronize multiple devices, but there is nothing wrong with doing a periodic SYNC. How often do you plan to apply the SYNC signal?
  • 0 in reply to Tom Hendrick
    Prodigy 105 points

    Tom,

    We would apply the signal periodically at a "high" rate - say, once per second.  The concern is will this periodic reset - a multiple of and synchronous with the output data rate - cause the filter to reset and invalidate the data until the settling time has elapsed or will the filter be unaffected as long as the reset fulfills the above conditions (multiple of the output data rate and synchronous with the output data)?

    Thanks

    EB

  • 0 in reply to Eric Boler
    TI__Guru**** 181521 points
    Hi Eric,

    Refer to the SYNCHRONIZATION section of the datasheet on page 27 along with figures 73 and 74 on page 78. Pulsing SYNC resets the filter, which causes DRDY to stay high (in SPI mode) or DOUT to stay low (in Frame Sync mode) while the filter settles, so you will have some data lost with each reset cycle.