Hello,
We have used eFuse chip TPS259827ONRGER in our product. Recently, we have a malfunctioning board returned from our customer. We found two of the eFuse chips were physically damaged. It seems that one is totally burned and the other also has a bulge on its top surface, as shown in the pictures below.
We have tried to figure out the root cause of this kind of damage.
First, we suspect if it is really caused by extremely high current going through it. But it seems there is no indication on the output side of eFuse on the board, there is no burned PCB traces or connector pins. And eFuse chip is supposed to shut down its output when high current appears. So we think it is unlikely because of the high current.
Then, We are thinking if any reverse voltage can cause the damage. We have reverse protection at eFuse input, but not output. Then we tested to connect +5V, +12V, +24V, -5V, -12V and -24V at the eFuse output without supply power on its input side. and above test didn't damage the eFuse. Of course, when all negative voltages were applied, they were clamped to -1V by a TVS (SMAJ24A-13-F) at the output of our board.
Last, we wonder if any shortage on eFuse output side (there is more damage on that burned chip on its output side) could burn it. For example, some shortage between the board and metal enclosure for whatever reason. But we have tested that output shortage is also protected by eFuse and this is also a function and feature of the eFuse chip.
The schematics of the eFuse is shown below. Do you have any suggestions of the cause of this kind of damage. Is there other users experiencing similar thing? Thank you!
Best Regards!
Michael
