MCP73831/2: Strange Issue

[NikhilRockssss]

Hey EEVBloggers,

I'm having an issue with MCP73831/2. It's part of this wearable I've been designing, and so far it's been working great when I was working on it on the development board. Then I integrated it into a case, and there is this one very strange issue.

We are charging a LiPo with 220mah with a RPROG of 4.7K. VDD and VBAT are both bypassed by a 4.7uF (According to the DS). Now, once this is done, it works flawlessly for days and weeks, but suddenly, it blows up, even when it's not charging. We open up the body, and find that VBAT and GND have been short circuited internally in the IC.

We initially thought it was due to high junction temperature, but the fact that it blows up even when there's no charge across it, is worrying 

Please help. I've attached a pic of the circuit we're using for your reference.

Thanks!

Nikhil G.

[phenol]

I had this chip blow up on me mysteriously a number of times  until i found out that it is rather intolerant to voltage transients on its input due to ringing caused by the low esr mlcc and cable inductance. A small tvs on the input solved the problem.