Pre-biased NPN with integrated 4.7 kOhm resistors
The BCR 112T E6327: The Infineon BCR 112T is a pre-biased NPN digital transistor in a PG-SC-75 surface-mount package. It integrates both a base resistor (R1) and a base-emitter resistor (R2), each 4.7 kOhms, eliminating two external passives per transistor on the board. This part is designed for low-current switching applications where the bias network is fixed and the transistor is driven directly from a logic output or microcontroller GPIO.
Key ratings for switching and drive
Collector-emitter breakdown is rated at 50 V, with a maximum continuous collector current of 100 mA — suitable for driving relays, small solenoids, LEDs, or as a logic-level translator up to that voltage rail. The DC current gain (hFE) is a minimum of 20 at 5 mA collector current and 5 V VCE, typical for a pre-biased part where the gain is intentionally modest to ensure saturation with a known base current. VCE(sat) is 300 mV maximum at 500 µA base drive and 10 mA collector current, confirming the transistor saturates cleanly for low-side switching. Transition frequency is 140 MHz, which means the device can handle switching frequencies into the low-MHz range — fine for PWM dimming, buzzer drive, or signal inversion up to a few megahertz. The 250 mW power dissipation limit in the SC-75 package means the part is not intended for continuous high-current loads; it is a signal-level switch.