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ADS124S08: Common and Differential Input Impedance for the Mux/PGA

Ethan Goldstein
Prodigy 90 points
Part Number: ADS124S08

Hello,

I would like to know the differential and common mode input impedance for the mux/PGA. Unfortunately, it does not appears this information is in the datasheet. Please provide.

Thank You,

Ethan

  • +1
    TI__Guru** 113765 points

    Hi Ethan,

    The input to the PGA is considered high impedance as the input with the PGA enabled is similar to an instrumentation amplifier (GΩ).  Impedance is dynamic with respect to various factors so it was decided that input current characteristic graphs would be used instead of giving an impedance value to give a more true perspective.  The input current graphs are available for both PGA enabled and PGA disabled.  The datasheet graphs begin with Figure 8 with absolute input current with respect to input voltage.  These graphs are showing primarily input leakage.  Differential input current graphs begin with Figure 12.

    Best regards,

    Bob B