Part Number: TCA9617A
In the failing assemblies, the TCA9617A drivers the B-side signals are permanently Low.
During power-up, the output SDAB already drives Low when VCCB is applied, although EN
is still Low at this time. After EN becomes High, SDAB remains permanently Low and does
not follow the input signal SDAA.
The same behavior is observed on the clock line: SCLB does not follow SCLA and also
remains Low.
Using the A-B-A component swap method, it was verified that the malfunction follows the
TCA9617A device when moved between several assemblies.
You can find the detailed analysis in the document attached.
TCA9617A_Error_Report.pdf
