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PGA281: SPICE model- includes Chopper characteristics?

Mark Pieper
Expert 4660 points
Part Number: PGA281


Tool/software:

Hi Amps Team,

Does the SPICE model for this part include the chopper circuitry? In particular, my customer is looking to reflect the ripple/noise induced by the chopper function in the simulations. 

Thanks,

Mark

  • +1
    TI__Mastermind 33723 points

    Hey Mark,

    It looks like the input current is modeled as a DC 250pA and 350pA of bias current. Unfortunately it does not appear to be modeled in SPICE.

    Best,
    Gerasimos

  • 0 in reply to Gerasimos Madalvanos
    TI__Expert 4660 points

    Hi Gerasimos,

    Thank you. I'll relay this answer to the designer. It might be sufficient to consider the noise mathematically. 

    Referring to figure 49 on the DS page 22, which of the amplifiers are chopper stabilized? I see that external filtering is suggested (7.3.1.7) to attenuate this noise but the noise amplitude isn't defined in the DS, unless I don't know what I'm looking for. Is this quantified anywhere?

    Thanks,

    Mark

  • 0 in reply to Mark Pieper
    TI__Mastermind 33723 points

    Hey Mark,

    Just wanted to double-check the figure reference from the datasheet.

    Page 22 seems to only have Quiescent Current, Settling Time, and Overload Recovery, as well as figure 46.

    Figure 49 seems to have the PLC input example circuit, and has only the PGA in there

    Could you please clarify which figure you are referencing?

    Additionally, I don't see any Ib over Time graphs in the datasheet, I don't believe the amplitude of spike is characterized. I may be able to get the input current over time of a single unit, but it would not be a representative sample.

    Best,
    Gerasimos