Other Parts Discussed in Thread: ADS1255
Hi,
I have an ADS1256 that I want to use to measure microvolts amplitude signal ~5 uV pk-pk. According to the datasheet, with a data rate of 2000SPS and PGA = 1, the Input Referred Noise (μV, rms) with Buffer Off is 4.025 uV which according to a thread I've read is the minimum voltage that the ADC can measure. I'm also a bit confused about the meaning of the full-scale range. When for example it says FULL-SCALE INPUT VOLTAGE VIN(1) (VREF = 2.5V) = ±78.125mV for PGA = 64 is this range from 0 to 156.25 mV or from 2.5V to 2.65625. Because my original small signal (~5uV pk-pk) was centered at 0 so I had to level shifted it so that it can be read by the ADS1256. The problem now is that the level-shifted signal isn't centered at 2.5 V or 78.125mV. The offset varies in terms of the input voltage. For a +/-2.5 V pk-pk signal, the level-shifted signal is centered at 1.6 V.