Pre-biased NPN for automotive switching — what the ratings tell you
The Infineon BCR108WE6327 is an NPN pre-biased digital transistor in a three-pin SC-70 (SOT-323) package, qualified to AEC-Q101 for automotive applications. The built-in bias network — a 2.2 kΩ series base resistor (R1) and a 47 kΩ base-emitter resistor (R2) — eliminates the need for two external passives per transistor, shrinking board area and reducing pick-and-place cost in high-density modules like engine control units, transmission controllers, or body electronics. Collector current is rated to 100 mA, and the collector-emitter breakdown voltage holds at 50 V, covering 12 V and 24 V automotive rails with margin. The 170 MHz transition frequency means this part switches cleanly into the low-MHz range, suitable for gate-drive interface, level translation, and relay or solenoid pre-driver stages.
Saturation and gain — the real-world switching numbers
Vce(sat) is specified at 300 mV maximum with a 500 µA base drive and 10 mA collector load — a typical forced-beta condition that tells you the part saturates hard enough to keep dissipation low in a logic-level switching job. Minimum DC current gain is 70 at 5 mA Ic and 5 V Vce, so the pre-biased resistor divider is designed to guarantee adequate base overdrive across the 100 mA operating range. Collector cutoff current is just 100 nA maximum, which matters for low-leakage automotive off-state requirements.
The AEC-Q101 qualification certificate and the datasheet are manufacturer-published and current.