Screenshots from emuonpsp show that the Blackfin uses an Actel A3P250-VQG100 (FPGA) as its main CPU and an FTDI FT2232HL for USB communication.
http://wololo.net/2016/06/10/psvita-...obra-blackfin/
http://wololo.net/2016/06/10/psvita-...obra-blackfin/