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ADS124S06: ADS124S06 Absolute input current vs. Differential input current

Masa Katayama
Intellectual 970 points
Part Number: ADS124S06

Dear Sir,

May I ask a difference of meaning / definition between the subject current specified in Electrical Characteristics table of d/s? 

It looks not just half current value for differential at PGA condition and typical. 

Best regards,

Masa 

  • 0
    TI__Guru** 113765 points
    Hi Masa-san,

    We have graphs in the datasheet (Figures 8-15) to help illustrate the current for the various conditions for differing temperatures and input voltages as well as whether the PGA is enabled or disabled to help illustrate the effects of the differential current and the absolute current. These currents can cause error in the measurement if filter resistances are large relative to the input impedance. Input bias current changes by a much larger factor between PGA disabled and PGA enabled.

    You would be most interested in the absolute current when measuring single-ended which is primarily indicating sampling bias current (mostly form the chopper input). But this absolute current is also an indicator of internal switch leakage relative to input voltage and temperature, as well as any leakage through the ESD structure.

    The differential current also looks at the input bias currents, but through the entire full-scale range indicating the amount of current in the differential measurement. Differential current is largest at the maximum input voltages, and 0 when a 0V input is applied.

    Best regards,
    Bob B