We're seeing an odd behavior in the STBC03. We keep BATMS_EN asserted at all times, as we are not worried about wasting that little bit of power. Once in a while (1%?), on power up, BATMS_EN is high, the LDO is outputting 3V, the battery is ~4V, but the BATMS output is 0V.
Are there any startup timing issues for the BATMS_EN pin? Of course, we'll try deasserting and reasserting it in firmware, but we'd also like to know if there are any internal hardware or logic considerations in the chip that would be helpful to know about.
I do see in the datasheet that overcurrent, battery overdischarge, shutdown enable, SYS or LDO short, etc., can open the connection from BATSNS to BATMS, but we shouldn't be seeing any of those cases in our use.
Project details that may be relevant: SYS is unused and has bypass cap. Switches are unused and all related pins are tied to ground. SD is held low by micro. Input is 5V from LDO. CHG has a pull-up at the micro. CEN and WAKE are floating. 15mAh battery. Circuit draws <10mA peak.
This is a mature project with hundreds of good units in the field, but we're trying to track this down.
