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ADS124S08: ADS123S08 REFCOM connectivity

Drew Hoyt
Prodigy 10 points
Part Number: ADS124S08

Per the ADS124S08 datasheet - it is recommended to tie REFCOM to AVSS when using the internal reference.

I am currently using this design with AVDD=2.625 and AVSS=-2.625 supplies and it would be useful instead of trying REFCOM to AVSS I could tie it to ground - so that relative to the rest of the board, REFOUT is +2.5V rather than -0.125V.

Is this a supported configuration of the device? Is the reason for the recommendation to tie to AVSS to ensure that there is enough headroom from REFCOM to AVSS, just a recommendation for a low, quiet voltage to tie it to, a requirement due to some internal protection circuits, or something else?

Thanks,

Drew

  • 0
    TI__Guru** 113765 points

    Hi Drew,

    Welcome to the E2E forum!  It is true that some headroom is required, but it is important that REFCOM be connected to AVSS instead of some other point.  The design of the internal reference is based on a connection to AVSS and if connected to some other point (such as AGND using bipolar supplies) the REFOUT could oscillate and not be stable.

    Best regards,

    Bob B