• State Resolved
  • Locked Locked
  • Replies 2 replies
  • Subscribers 47 subscribers
  • Views 428 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

Using ADS1298 or ADS1258 with very weak signals?

Srini Vas
Prodigy 20 points
Other Parts Discussed in Thread: ADS1258, ADS1298, ADS1282

We're looking at using 1298 or 1258 as the analog front end for our application. But unlike ECG inputs, some of our input signals are extremely weak: approximately 0.01 Hz and 10-300 microVolts and some inputs in milli Volts. Will it be possible to use the AFE based on either of the above two chips or should I be looking at a different product? If it is possible, What kind of changes would I need? thanks!

Srini

PS.Sorry if I sound too naive.

  • 0
    Prodigy 40 points

    In ECG signals are not much stronger that you wrote. Of course 10uV is weak, but taking into account that it has too low bandwidth 0.01Hz you can average it. Everything depends on snr you need.

  • 0 in reply to Dmitry Kuznetsov
    TI__Expert 4575 points

    What about  the requirement of your system accuracy?  It seems that the internal PGA is too small in ADS1298, ADS1258.

    1)  Page 7 of ADS1298, Table 1,  you see, the Max. PGA gain is 12,  the Input-Referred Noise  when PGA=12 & Output data Rate=500 is 2.9uV(p-p). which is less than your 10uV,  no problem, but when your reference voltage is 2.4V, then full input voltage is 200mV ( 2.4v/ 12),  you input signal range is 0.15% of the full-input of ADC.  so not sure ADS1298 can meet your system accuracy.

     I think ADS1282 is the best  one for you. input Offset is 1uV Typ. after calibration, and  Internal PGA is up to 128, very lower input-reference noise of PGA. Just for reference.