Pre-biased NPN in a SOT-23 footprint
The Infineon BCR108E6327HTSA1 is an NPN pre-biased transistor that integrates two bias resistors — a 2.2 kOhm base resistor (R1) and a 47 kOhm emitter-base resistor (R2) — into a single PG-SOT23 package. This eliminates two discrete passives from the BOM and shrinks the placement area for switching and driver circuits where the base bias network is fixed. The device is rated for a 50 V collector-emitter breakdown and handles a continuous collector current of 100 mA, with a transition frequency of 170 MHz that suits moderate-speed switching up to the low-MHz range.
Last-time-buy — plan the BOM move now
The BCR108E6327HTSA1 carries a Last Buy lifecycle status. That means Infineon has issued a final purchase window, after which the part will no longer be manufactured. For any design still using this exact ordering code, procurement should secure the remaining lifetime volume or qualify a drop-in replacement before the LTB window closes.
R1 and R2 — the bias network is baked in
The integrated resistor divider sets the base drive relative to the collector load. With R1 at 2.2 kOhm and R2 at 47 kOhm, the transistor turns on when the input voltage exceeds roughly 0.7 V plus the divider ratio — a common configuration for low-side switches, relay drivers, and logic-level interface circuits where the base current is limited by the internal resistor. The 300 mV saturation voltage at 10 mA collector current (with 500 µA base drive) keeps conduction losses low in saturated switching.