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ADS1298 Input Configuration

Oscar Baumann
Intellectual 835 points
Other Parts Discussed in Thread: ADS1298, ADS1298ECGFE-PDK

Tom, in pin vrefp and vrefn, If i use internal reference I have to put a voltage between those pins? In bipolar configuration? My analog supply configuration is +-2.5v and 3.3 digital supply. Vrefp and vrefn, In bipolar configuration the (-) electrode of electrolytic caps goes to -2.5v, the same case for vcap1, vcap2, vcap3, etc? Thanks again.

The (-) electrode goes to -2.5.?

  • 0
    TI__Guru**** 169105 points

    Hi Oscar,

    If you are using the internal reference of the ADS1298, you do not need to apply an external voltage to REFM and REFP.  When using an external reference, REFM should go to the lowest potential and REFP to the highest.  For example, if you have your board configured for bipolar +/-2.5V using the internal 4V reference, if you measure VREP with respect to AGND, it would read ~1.5V.  If you measure VREP with respect to AVSS, you should see 4.0V.  VREFM needs to be referred to the -2.5V rail as does the (-) electrode of your capacitor. 

    Take a look at the schematic in the ADS1298ECGFE-PDK Users Guide, this might help.  You can also send along the ADS1298 portion of your schematic to us and we'd be happy to review it for you.