The 2SA1943 is a high power PNP transistor originally from Toshiba. Due to its high current gain and collector current it is very commonly used in High power audio circuits or AF amplifiers. The is a high power PNP transistor originally from Toshiba. The PNP equivalent is the complimentary transistor, which is the BC557. This is identical in every respect to the NPN type, except that it is a PNP type. The complimentary transistor is very useful for symmetrical push-pull amplifier circuits. Jul 17, 2019 · BC557 SMD DATASHEET PDF - BC ON Semiconductor / Fairchild Bipolar Transistors - BJT PNP V mA HFE/ datasheet, inventory, & pricing. BC BC VCEO. − − − Vdc. Collector - Base Voltage.