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AD7944 only toggles 4 bit at output

Hi,

I'm using 2 14-bit AD7944 ADCs on a imaging prototype board, one of them works perfectly, but the second one only toggles the 4 MSB regardless of the input, and the rest are either all 1s or all 0s - I've double checked the CNV control signal and the SCK via oscilloscope at the input of the ADC and made sure to disable the other ADC while one of them is running. Any ideas/suggestions?

 

 

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