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ADS1248 multiple parts in system, best approach

Chris Forte
Intellectual 310 points

I am using 8 parts per PCB. All have separate SPI bus to controller. I am exploring advantages / disadvantages to either:

1. Poll all 8 ch in sequence for conversion data.

or

2. Synchronize all converters to have data ready at same time.

Any ideas much appreciated.

  • 0
    TI__Guru* 92655 points

    Chris,

    I don't think either way makes a difference from a technical standpoint. If you need data to be synchronously sampled, that would be one thing, but by your question, I'm guessing that you don't need it.


    If you posted more detail about what you were measuring and configurations, it might shed more light to an answer.

    Joseph Wu

  • 0 in reply to Joseph Wu
    Intellectual 310 points

    Hi Joseph,

    My design is an 8 ch RTD. RTDs have a very slow thermal response (.5s) so speed is not an issue. I am trying for best system accuracy (lowest noise).

    Chris

  • 0 in reply to Chris Forte
    TI__Guru* 92655 points

    Chris,

    I don't know if you've seen this link or not, but there's a few examples of RTD use in this application note:

    http://www.ti.com/lit/an/sbaa180/sbaa180.pdf

    To be honest, I don't think it matters if the readout is synchronous or one at a time. They should have the same noise performance. The only thing that I can think of going wrong is if the digital currents caused more noise when things were read out synchronously. However, you can get around that with a decent layout.

    Joseph Wu