Original question:
ADS1015-Q1: Internal input resistance and capacitance of S/H block
I am trying to fill in the ADC input impedance equivalency diagram above for the ADS1015. Can you please advise what is C_S (min and max and typ) and C_p1 and C_p2?
also , what is the total unadjusted error in LSB (includes offset error and full scale error), and Differential non-linearity error of ADC in LSB?
I do not see these values in the datasheet
Thank you!
Hello,
I am trying to fill in the ADC input impedance equivalency diagram above for the ADS1015. Can you please advise what is C_S (min and max and typ) and C_p1 and C_p2?
The ADS1015-Q1 is a delta-sigma ADC so generally it will appear resistive to signals in the input range as it is continuously charging and discharging. This other E2E post is a good reference for more details: https://e2e.ti.com/support/data-converters-group/data-converters/f/data-converters-forum/1226346/ads1015-q1-internal-input-resistance-and-capacitance-of-s-h-block/4632466?tisearch=e2e-sitesearch&keymatch=input%2520capacitance%2520delta%2520sigma#4632466
what is the total unadjusted error in LSB (includes offset error and full scale error), and Differential non-linearity error of ADC in LSB?
The error values are listed in the datasheet under system performance on page 5 of the datasheet:
The total unadjusted error will depend on your particular situation, including the PGA range you program into the device, but can be calculated using the Analog Engineer's Calculator: https://www.ti.com/tool/ANALOG-ENGINEER-CALC
I ran a brief calculation for you using the tool and a ±2.048V input range and arrived at a TUE of 395 ppm of error:
Let me know if you have any more questions,
Levi DeVries
