Pre-biased NPN in SC-70 — what the BCR108WH6433XTMA1 is
The Infineon BCR108WH6433XTMA1 is a pre-biased NPN transistor in the SC-70 (SOT-323) surface-mount package. It integrates the base bias resistor (R1 = 2.2 kOhms) and a resistor from emitter to base (R2 = 47 kOhms), eliminating two external components per switching node.
Ratings that define the switching budget
Collector current is rated 100 mA maximum, with a collector-emitter breakdown voltage of 50 V — enough for most 12 V and 24 V industrial logic interfaces. The 170 MHz transition frequency means it handles switching up to a few tens of MHz cleanly, though the integrated resistors limit the edge rate compared to a bare transistor. Saturation voltage is specified at 300 mV at 500 µA base current and 10 mA collector current — the pre-bias ratio (R1 / R2 ≈ 0.047) keeps the transistor in saturation with a modest input drive. DC current gain minimum of 70 at 5 mA, 5 V confirms it saturates reliably in the low-current regime.
NRND — not for new designs
Infineon has not announced a direct successor in the BCR108 base product number family, so existing production slots or surplus stock are the sourcing channels. For a BOM line that is still in qualification, this part is still obtainable through independent distribution against an RFQ — but a new design should select a current-production pre-biased NPN in the same SC-70 footprint.