AD7147-1 bias voltage issue

Q: AD7147-1 bias voltage issue

Question: It had been reported that after 2-3 month in the field, the AD7147-1 stopped responding!! The issue had been observed in few samples. Answer: Upon detailed analysis, it was found that the BIAS voltage is becoming zero instead of (VCC/2). The unused CIN pins were connected to the External Bias. The recommendation for unused CIN is to connect them to internal BIAS by S/W configuration. Also, in the case of unused input channels, the recommendation is not to connect to CDC inputs so that there is no electrical connection from the external bias pin to the inbuilt bias via unused CIN pins.

Question:

It had been reported that after 2-3 month in the field, the AD7147-1 stopped responding!! The issue had been observed in few samples.

Answer:

Upon detailed analysis, it was found that the BIAS voltage is becoming zero instead of (VCC/2). The unused CIN pins were connected to the External Bias. The recommendation for unused CIN is to connect them to internal BIAS by S/W configuration. Also, in the case of unused input channels, the recommendation is not to connect to CDC inputs so that there is no electrical connection from the external bias pin to the inbuilt bias via unused CIN pins.