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ADS124S08: ADS124S08 DOUT/DRDY pin question

Sulyn ZHANG
Expert 8700 points
Part Number: ADS124S08
Other Parts Discussed in Thread: ADS1247

Hi Team,

My customer is upgrading Old ADS1247 to our latest ADS124S08 with our penetration. One question want to double check with your one question about DOUT/DRDY pin function.

As for ADS1247, we in fact has described in datasheet that:

It seems in SDATAC mode, DOUT/DRDY pin can't work in DOUT/DRDY mode 1.

So the similar question for ADS124S08 is that are these some modes will limit DOUT/DRDY pin can't work in DOUT and DRDY mode? If these are, pls let me know which modes? I can't find some information about this, need your kindly help to confirm.

Thanks.!

Best regards,

Sulyn

  • 0
    TI__Guru** 113765 points

    Hi Sulyn,

    The digital portion for the ADS1247 and the ADS124S08 are quite different.  For example, there is no longer a SDATAC command for the ADS124S08.  Also, there is no register setting to turn on/off the DOUT/DRDY function mode for the ADS124S08.  For the ADS124S08 the DOUT/DRDY will always follow the DRDY when DRDY transitions low, DOUT/DRDY will also go low (or it will pulse if it is already low).  But as the DOUT/DRDY is controlled by CS, the state of the CS will also determine the state of the DOUT/DRDY pin.  If CS is high, then DOUT/DRDY will be high impedance.

    One further consideration is the previous state of DOUT/DRDY after a conversion result is read or if registers are read.  In this case the last bit transmitted will determine the state of DOUT/DRDY until the next conversion completes. When using an interrupt driven system that is looking for a high to low transition on DOUT/DRDY, this should not be an issue.  However, if polling the DOUT/DRDY pin for the transition, the point of change can easily be missed or misinterpreted due to the short duration of the pulse.  In this case you want to force the state of DOUT/DRDY high.  See the last paragraph shown on page 71 in section 9.5.5 for further details.

    Best regards,

    Bob B