We have just introduced our product into the field and we are now seeing the BQ34Z110 gas gauge fail on most of the units. The failure is that the REGIN goes short circuit to ground, REG25 goes short to ground and a number of other pins measure low resistance to ground. The units have had many hundreds of hours of in house and third party immunity testing under all kinds of conditions with no failures. The gas gauge is used with a 24V PbA battery using the mosfet source follower regulator circuit to regulate REGIN at 3.6V. This regulator also fails - it gets blown open by the downstream failure of the gas gauge. We have looked at a working linear regulator circuit under different conditions (Vin, temperature) and not seen any issues with it. Our workaround for the moment is to power REGIN from a permanent short circuit protected 3.3V supply rather than use the mosfet source follower regulator but we are uncomfortable with not knowing the exact cause of the problem. Has anybody seen anything similar and have any ideas on what the problem might be?
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