Small-signal PNP for general-purpose switching and amplification
The Infineon BC 856BW E6433 is a PNP general-purpose transistor in the SC-70 / SOT-323 package, rated for 65 V collector-emitter breakdown and 100 mA continuous collector current. Maximum power dissipation is 250 mW, and the junction temperature rating extends to 150 °C.
The 65 V Vceo gives headroom for 24 V or 48 V rails with derating margin, while the 100 mA Ic(max) covers relay drivers, LED switching, and logic-level interfacing. The 250 mW power limit in the SOT-323 package means the part is best suited for low-duty-cycle or moderate-current applications; continuous dissipation above about 150 mW at 25 °C ambient needs a layout that pulls heat into the board. The 250 MHz fT is fast enough for audio-band amplification and moderate-speed switching up to a few MHz, but not intended for RF power stages. The collector cutoff current of 15 nA (max) ensures low leakage in battery-powered or high-impedance circuits.
Infineon lists the BC 856BW E6433 as obsolete. For new designs, consider the broader BC856 family in SOT-323 (e.g., BC856B or BC856A variants) which share the same pinout and similar DC characteristics; verify the hFE grade and Vce(sat) match your circuit.
SOT-323 footprint and rework considerations
The SC-70 / SOT-323 package is a three-lead surface-mount device with a 1.3 mm body width. It is rework-friendly under hot air at 300–350 °C with a fine nozzle; the small thermal mass means it solders quickly and is less prone to tombstoning than smaller packages. Pin 1 identification is marked by a bevel on the package body — confirm orientation before placement. Standard SOT-323 footprint applies; no exposed pad.