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ADS8363: Data output ~13 dB greater than nominal

Part Number: ADS8363

The problem I am seeing is that I have two of the same board, each with an ADS8363 on it.  One board provides a digital output that is ~13 dB higher than the other with the same input signal applied to the ADC input.  I cannot understand how this can happen.  The part is used with a grounded  SDI input and M1=M2=0 so that all registers should be defaulted.  I cannot find anything physical on the boards  that could cause the parts to behave differently so I am looking for advice on how to troubleshoot this. Is there an internal mode that would cause the serial digital output to have decoded output that is ~13 dB higher? I currently do not have access to read the internal registers, but could with some effort.

Case CS0134878 was original correspondence with TI. 

  • Hi David,

    Thank you for your post. Two quick debug steps that come to mind:

    1. Can you please probe both REFIO pins to confirm that the expected 2.5 V is coming from both reference buffers?
    2. Can you probe the SPI to confirm that your controller is latching data correctly and reading the same values as seen by a logic analyzer? Such a difference in magnitude may be explained by a bit-shift or missing some MSBs.

    Best regards,