The STPSA92 is a high-voltage small-signal PNP transistor from STMicroelectronics, rated for 300 V collector-emitter breakdown and 500 mA continuous collector current. The 50 MHz transition frequency places it in the switching transistor class, suitable for line drivers, relay coil drivers, and high-voltage signal switching in telecom or industrial control boards. The TO-92-3 through-hole package keeps the footprint compatible with legacy designs and prototyping sockets.
Key ratings for the BOM decision
The 300 V Vceo is the headline spec — this transistor can hold off 300 V between collector and emitter. The 500 mV saturation voltage at 20 mA collector current (with 2 mA base drive) means the on-state loss is low enough for a 20 mA load without a heatsink. The 100 nA collector cutoff current (ICBO) keeps leakage negligible at room temperature, though it will rise with junction temperature — the 150°C junction rating gives headroom for warm environments.
STMicroelectronics lists the STPSA92 as obsolete.