Two pre-biased NPNs in one SOT-363 — what you're looking at
The BCR108SH6433XTMA1 from Infineon packs two NPN transistors with integrated bias resistors into a single 6-pin SOT-363 package (PG-SOT363-PO). Each transistor has a 2.2kΩ series base resistor (R1) and a 47kΩ resistor between base and emitter (R2), so you can drive them directly from a 3.3V or 5V logic output without external resistors. Collector-emitter breakdown is rated at 50V, continuous collector current at 100mA, and the transition frequency hits 170MHz — fast enough for switching up to a few MHz. Total device dissipation is 250mW.
Where this part lives on a board
These dual pre-biased transistors are a space-saving choice for driving relays, solenoids, LEDs, or small loads from a microcontroller's GPIO. The integrated bias network eliminates two resistors per channel, which shrinks the BOM and board area. You'll find them in industrial control panels, appliance PCBs, and automotive body modules where a simple high-side or low-side switch is needed. The SOT-363 footprint is surface-mount, so it flows through standard reflow soldering.
Infineon has marked the BCR108SH6433XTMA1 as Obsolete. If you have this part on a current BOM, you need a plan.
The scorch mark tells you — finding a replacement
If you are repairing a board and the original BCR108SH6433XTMA1 is the part that failed, you need a drop-in. Infineon's base product number BCR108 covers a family of pre-biased transistors. The closest functional equivalent shares the same SOT-363 footprint and the same internal resistor values (2.2kΩ base, 47kΩ base-emitter). Any dual NPN pre-biased transistor in SOT-363 with those resistor values and a 50V, 100mA rating is a candidate. Verify the pinout matches your board layout before committing — the SOT-363 pin arrangement is standard, but always check against the original.