Pre-biased NPN in a compact SOT-323
The Infineon BCR119WH6327 is an NPN pre-biased transistor — a digital transistor with a 4.7 kΩ base resistor integrated on-chip. It's designed to replace the discrete resistor + BJT pair in low-current switching and driver stages, saving board space and reducing pick-and-place cost. With a 50 V collector-emitter breakdown and 100 mA continuous collector current, it suits relay drivers, LED switches, and logic-level interface circuits in industrial and consumer equipment.
Switching performance and bias design
The integrated base resistor (4.7 kΩ) sets the base current for a given drive voltage, simplifying the input stage. Minimum DC current gain is 120 at 5 mA, 5 V, ensuring adequate drive for loads up to 100 mA. The 150 MHz transition frequency supports switching in the low-MHz range. Saturation voltage is 300 mV max at 500 µA base, 10 mA collector — low enough to keep dissipation minimal in saturated switches. Collector cutoff current is just 100 nA, useful in battery-operated circuits where off-state leakage matters.
Package and thermal considerations
Maximum power dissipation is 250 mW for the SOT-323 package. In a 100 mA switching application, ensure the collector-emitter voltage drop times current stays well under this limit, or derate for ambient temperature above 25 °C. The small footprint suits dense PCB layouts, but thermal coupling to the board copper is necessary for sustained loads near the maximum.