TIers,
I am hoping for your input on a new BQ24600RVAT battery charger design. The design was mostly based on a TI reference design. The MOSFETs had to be substituted due to availability. The design is intended to be a 24 V input to charge a 12.6 V battery.
When power is first applied to the board even with no battery connected, the supply is pulling max current (7+ A) so it looks like there is a short or miss on the circuit design. When I remove the MOSFETs (2 N-channel single package - HS8K11TB) then the rest of the board operates normally. So it is definitely isolated to the battery charger circuit. This happens even when the CE pin on the BQ24600RVAT is not pulled high.
I have compared my schematic to the reference design and can't find any major differences outside of the MOSFET swap. Connections seems correct on my review. The substitute MOSFET does not support as much current as the reference design, but again, there isn't even a battery connected to charge
There is a chance there is an assembly issue, but 2 out of 2 boards currently have the issue.
Schematic is attached. The rapid heating is seen in Q4. Thanks!
Kris