Pre-biased NPN for space-constrained switching
The Infineon BCR141W is an NPN pre-biased transistor in a SC-70 (SOT-323) package, integrating two 22 kΩ resistors — one in series with the base, one between base and emitter. This built-in bias network cuts external component count, useful when you need a simple switch or driver on a tight board. Collector current is rated to 100 mA, with a collector-emitter breakdown of 50 V and transition frequency of 130 MHz.
Sizing the load and drive
The 100 mA collector current sets the ceiling for loads like small relays, LEDs, or logic-level interface inputs. Saturation voltage is 300 mV at 500 µA base current into 10 mA collector current, so it switches cleanly with modest base drive. For higher collector currents, check the hFE of 50 minimum at 5 mA, 5 V.
Package and handling
The PG-SOT323-3-1 supplier package is the same footprint. Maximum power dissipation is 250 mW, so keep an eye on the thermal budget if driving near the current limit continuously.