Output of MPM3683 spikes to level of the input

DC-DC Power Converters
1

Hi,
I’ve been using an MPM3683 on several designs for a long time.

On a new set of boards, I’ve been observing an intermittent issue. Approximately half of the boards come up fine, and the output rail from the device stays stable and at the level I programmed it to.
On the other half, the output comes up either low (ex: 2.5V instead of 6V) or at ground (no shorts on board prior to power on). Then it begins to spike up to the level of the input (ex. 18V). This is damaging my components. The MPM3683 also heats up significantly, much hotter to the touch than a working board.

Have there been other reports of an issue like this? Could a damaged device be causing this, or is there another possibility?

Thanks!

2

Hi mross,

There is a keep out area on the back of the chip:
image

Please make sure none of those pins are electrically connected. Similar issues have been seen on other parts where the keep out area was not respected or there was a solder bridge. This can cause the device to operate abnormally and cause damage to the device.

You can try checking your reflow profile. For more information regarding QFN manufacturing, please check out : monolithicpower.com/en/documentview/productdocument/index/version/2/document_type/Article/lang/en/sku/MPM3630GQV/document_id/10121/

Regards,
Vinh Tran