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How is the ADS1015 "virtual reference" managed?

pj_colorado
Prodigy 10 points

I'm not finding the detailed answer I'm looking for . . .

Please explain "virtual reference" in more detail. Is gain essentially effected by reduction of the converter reference (from a fixed band-gap reference)? If the part is powered from a 2V rail, the band-gap is less than 2V, right? If the part is powered from a 5V rail, is the band-gap value still the same as when powered from 2V rail? There is no pump in the part to create a band-gap greater than the VDD rail, right? (Actually, I don't see how that could be possible, but I need to ask.) Please provide the details of how this is implemented, I need to understand how this works in detail.

Gracias!

PJ

  • 0
    TI__Guru* 92715 points
    PJ,


    The gain does come from managing the ratio of the size of the sampling capacitors compared to the reference sampling. The reference voltage comes from something lower than the min supply voltage of 2V and stays constant through changes in the supply. That's why the input range can be seen as something larger than the supply, even though there are limits on the inputs limited by the supply.

    Any more detail, and I'd consider it proprietary to our design.


    Joseph Wu