I am using two ADS8332 configured in daisy chain mode to provide a total of 16 analog readings. The ADC voltage conversions are about 20% less than the expected value.
The ADS8332 is configured as follows:
VA=5V, VBD=3.3V, VREF=4.096V. There is a buffer with a 5.3 MHz filter to drive the ADC Pin
I've taken some DC measurements when the voltage at IN1 is 1V:
- IN1: 0.986V
- VREF = 4.09505
In one case, the IN1 voltage is expected to be 1V, however the conversion result is 0.78V. (a count of 12335 decimal)
I took some scope measurements of the ADC IN pin during conversion. The green trace is the unfiltered OPA211 output, the yellow trace is at the ADCIN pin.
Pin IN1 has 0.486V on the input and all other channels are 0V. The ADC reading is about 0.38V (ADC count 23996)
The figure below shows ADCIN as the mux is switching sequentially from I0 through IN7.
Any advice is appreciated!