Our customer would like to know the actual input impedance value mentioned on the datasheet of ADS122C04.
Can you help?
Thanks a lot.
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TI doesn't specify a specific impedance value as the impedance is dynamic and there are a number of variables that affect input current with respect to bias current and leakage current. Instead of giving a general number characteristic graphs are given in the ADS122C04 datasheet to provide better understanding of the device behavior. The graphs start at Figure 4 and continue through Figure 11.
You will see from the graphs that the input current will change depending on temperature of operation, the input voltage and the PGA settings (enabled or disabled). The absolute input current best shows leakage behavior, whereas the differential current shows the measurement behavior.