Part Number: ADS1675REF
I would like to use the ADS1675REF board to sample a single-ended signal, but before I started, I found if J1 and J3 are floating, the ADC measured voltage is about 0.3V, J3 has 1.0V potential and J1 has 0.7V potential, while if J1 and J3 are short-ended, the ADC measured voltage is about -1.7V. I shorted J1 and connected J3 to a DC power supply, the ADC measured voltage is never equal to the DC power supply's output and shows an abnormal relationship.
Can anyone explain why? how can I use the ADS1675REF board to sample a single-ended signal? Is this problem related to the wrong use of the differential amplifier THS4503 as shown in the attached figure? Kindly note I removed the R44 which I thought was useless and might cause problems.
Many thanks in advance.