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Original question:

PGA308: What should I do if the input voltage signal is too large?

PGA308: total Offset drift and total gain drift

Isao Takigasaki
Intellectual 2500 points
Part Number: PGA308

Hi,

Could you provide equations to calculate total offset drift and total gain drift of PGA308?
My customer would like to estimate it at  any temperature.

Best Regards, Taki

  • 0
    TI__Mastermind 47796 points

    Hi Taki-san,

    Enclosed is PGA308 Transfer function, see image below. I am unable to comment on it without the schematic. Can you describe the application requirements?

    Drift data in this part is presented p.3-5 of the electrical table. Also see functional description in coarse and fine offset adjustment on p. 15 of the datasheet.

    Best,

    Raymond

  • 0 in reply to Raymond Zhang1
    TI__Intellectual 2500 points

    Hi

    The customer just want to know offset drift and gain drift of the device alone, so that they don't have any requirement from the application.

    How are both of the drifts calculated with the equation and the graph?
    Is "FRONT-END PGA OFFSET VOLTAGE" in Fig.4 means "(mux_sign * Vin + Vcoarse_offset) * GI"?
    If so, how should "COARSE OFFSET ADJUST ERROR" be applied to calculate the drift?

    I also found positive and negative value, +/-1ppm/deg.C in gain drift typ. in spec table.  Does it mean min and max, but not typ.?

    Best Regards, Taki