From our customer :
I worked with test on a U1, U3 failure where the output voltages of both IC’s were off by about 5VDC during ICT testing on 100% of the boards tested. U1 & U3 (TLV3701) is a relatively simple 5-Pin SOT-23 comparator in the DBV package which should have a specific output based on the two input voltages provided and is only found in these two reference designations.
After inspection and verification of associated components, it was apparent that the labeling on the IC’s in question happened to be slightly different than that of another board from a previous WO, this previous WO board was passing test without issue.
Considering the minor anomaly in labeling, I suggested U1 & U3 be swapped between a failing board and the passing board to see if the failure followed the components, and it did. These failing boards all had U1 & U3 components from a specific Lot/Date code, whereas the passing board was from a previous Lot/Date code.
With the components in question, it isn't uncommon to have an occasional failure, but as you know, we were seeing 100% failure rate with the comparators and changing them out with a different Lot/Date code fixed the problem 100% of the time.
Without disclosing any proprietary information, I can say that the input voltages to the comparator were not providing the expected output voltage, the measured output was between 4-5VDC higher than our tolerances allow. These are being used in an Over Temp Sense Circuit and Loss of Input Power Circuit, in qualified and extensively tested power supply boards.
Invoice: 113584310
PO is 4746685
date code and lot code is 2443 and 4484338PHI
