The Infineon BCR 135 B6327 is an NPN pre-biased digital transistor — a standard switching transistor with two bias resistors integrated into the package: a 10 kΩ base resistor (R1) and a 47 kΩ base-emitter resistor (R2). This integration saves one or two external resistors per channel on the PCB, which matters when you are populating a dense board or trying to reduce pick-and-place cost on a high-volume design. The part is rated for 50 V collector-emitter breakdown and 100 mA continuous collector current, with a transition frequency of 150 MHz — suitable for low-speed switching, relay and solenoid drivers, and general-purpose interface circuits where the load current stays under 100 mA. It comes in a standard SOT-23-3 surface-mount package (Infineon designates it PG-SOT23).
Infineon lists the BCR 135 B6327 as obsolete. For a sustainment program or a repair that needs this exact order code, the supply path is the independent distribution market — surplus inventory, overstock, or last-time-buy leftovers.
Saturation voltage and gain — the switching performance numbers
The Vce saturation is specified at 300 mV maximum with a 500 µA base drive and 10 mA collector current — a clean, low-drop switch for logic-level loads. DC current gain (hFE) is a minimum of 70 at 5 mA collector current and 5 V Vce, which is typical for a pre-biased part where the integrated resistors set the base drive. The 100 nA maximum collector cutoff current (ICBO) means leakage is negligible in off-state, so it will not pull a weakly driven output low.