Hello Mr. Bob,
I am now testing thermocouple input with ADS1148 for 8 channels on my PCB. The circuit design is as follows. Refer sheet2 and sheet3(Please visit the site to view this file)When I am connecting mV source signal individually to every input then my ADC code is not fluctuating and stable. But when I am connecting common mv source signal to all my inputs then I am seeing fluctuations in my ADC code. Also when mv source signal is changed the ADC code changes slowly. For connecting the mV source common to all inputs I have made VBIAS = 0. I have used single supply in the circuit using appropriate jumpers(S7,S11,S13 and S18) in the circuit. Please suggest whether any changes are required or where I am going wrong.
With Best regards,
Dhiren