B77S39 SOT device

I'm trying to identify a small SOT device B77S39 which has 6 legs ( three on each side )
The part number is in three roles so instead of reading accross and down , If I read it down then accross
the part number would be B737S9
On the device it reads
B7
7S
39

I didn't find anything on google or data sheetarchive.

Thanks
Dougy
.