What this PNP pre-biased transistor does — and the mistake it saves you from
The BCR 189T E6327: The Infineon BCR 189T is a PNP pre-biased transistor with a 22 kOhm base resistor built in, so you skip the external resistor pair that a discrete PNP would need for a simple switch. Rated for 100 mA collector current and 50 V collector-emitter breakdown, it handles low-side switching of relays, LEDs, or logic-level loads in compact designs. The 200 MHz transition frequency means it switches cleanly well into the low-MHz range, fine for GPIO-driven loads or signal inversion.
The 250 mW power ceiling — what it means on a small SC-75 footprint
With a 250 mW maximum power dissipation and a SC-75 (SOT-416) package, this part is sized for signal-level switching, not continuous high-current drive. At 100 mA collector current and a typical Vce(sat) of 300 mV at 500 µA base drive, the dissipation stays well under the limit for pulsed or low-duty-cycle loads. If your load draws 100 mA steady, check the junction temperature — the small package has limited copper to sink heat, and the 250 mW ceiling is the total, not per-pin.