Hi,
excuse my broad Subject and my inability to describe the problem better. As explanation, i'm a CS student with a bit of knowledge and micro soldering skills. The mentioned BQ25A is part in a broken laptop of me, and i'm struggling with figuring out whats wrong. My Laptop is a Razer blade 14 from mid 2014 so about 2 years old. VCC is 19V with 150W, 7.9A, ACFET,RBFET and BATFET are AON 6508 ers.
Me repairing it is the only solution because Razer fu**** su*** in out of warranty problem solving.
The first problem was that Q1 (ACFET) and Q2 (RBFET) were blocked all the time, preventing charging and using. It weirdly worked of a charged Battery, so it wasn't the short protection.
For your amusement, my first solution was un-soldering both FETS and bridging the pads with a wire. Used it like that for a week, but charging was a problem so i kept fiddling with it.
The current Situation is that both FETS are soldered in again and either Running of AC or Battery worked as intended, the other FETS where blocking as they should.
It just didn't work together. BATFET stayed charged, and ACFET and RBFET went charged, and pulled the power-supply down to battery voltage 12V, into over-current-protection. In that state, VCC was 12V,ACDET Below 2.35V, and ACOK low. No idea what or how that is possible, so i used it without battery on AC for while.
20 min ago it started to shut down under load, and while Debugging that, ACFET went up in magic-smoke.
shortly before that, ACDRV was only 18V instead of 19V and there was a voltage drop of more or less 1.5V on ACFET and that obviously killed it.
Questions.
Why do both States independently work, but not together ?
And what changed that ACDRV suddenly dropped and killed ACFET ?
Thanks in advance,
Sincerely Norman