Tool/software:
Hi,
I have a problem with my design using the LM22677-ADJ buck converter that appears to be sporadic. The design uses 3 of these buck converters on a board, bucking 26.5V down to 19V, 12V, and 5V. Typical output current is about 1A for each. The first round of prototype boards worked without issue, with stable output voltages on loads up to 4A.
On one (out of 5) of the beta boards, the buck converter IC for the 12V rail failed catastrophically with a hole blown out of the IC. I found that the schottky diode between GND and SW also failed, and assumed that that had somehow exceeded its reverse voltage rating, failed, and shorted SW to GND, causing the IC to fail. Replacing both the IC and the diode resolved the issue and that board is still functioning correctly.
The issue happened again today on the third round of boards with the 19V rail. The IC failed in the same way, with a hole blown through the IC. I've double checked that none of the pins exceed their rated voltage, and I don't see any voltage spikes on the input when powered on. I've never seen a failure of one of these ICs once they've powered up correctly, leading me to believe that there might be issues with the ICs themselves.
Any input or assistance would be great!
Thanks,
Jack
Buck Schematics
