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ADS1018-Q1: Input leakage current

Scarlett Cao
Expert 4650 points

Part Number: ADS1018-Q1

Hi team,

If customer is using ADS1018-Q1 ADC in single-ended configuration, and want to know the leakage curren. When I use I=V/R for calculation, shall I use the common mode input impedance only? Or need to calculate the leakage from common mode input impedance and leakage from differential mode input impedance?

Could you help share a diagram to show to how understand these two different impedance?

Thanks

Scarlett

  • 0
    TI__Intellectual 2340 points

    Hi Scarlett, 

    In a single-ended measurement the customer would need to use the input signal voltage divided by the common mode input impedance based on the Full-Scale-Range they will be using.

    I_Leakage = V_signal / R_cm 

    This simplification does not account for the leakage that occurs at an input voltage of 0V, but accounts for the worst case scenario at the full-scale-range. 

    Example:

    Single-ended at full scale range

    V_In = 2.048V, FSR  = 2.048 (Input Impedance @ 2.048V = 6Mohm) 

    I_leakage = 2.048V / 6Mohm ≅ 0.341uA

    Simplified single-ended diagram:

    Regards, 

    Andrew