I have a 2 cell lithium battery that's giving me some trouble and I'm trying to identify one of the parts on the protection circuitry. The part has the marking "3J40" on it. I believe the package is a SOT-23-6. I've identified the only other IC on the board as a MOSFET, which means the part I'm trying to identify is the controller part of the circuit. Does anybody know what part this is?