Two NPNs with built-in bias — what this means for the BOM
The ROHM IMH11AT110 packs two NPN pre-biased transistors into an SC-74 (SOT-457) surface-mount package. Each transistor integrates a 10kΩ base resistor (R1) and a 10kΩ emitter-base resistor (R2), eliminating the two external resistors normally needed per switching node. The symmetrical 10kΩ/10kΩ ratio gives a predictable input threshold and saturation behavior — useful for inverter logic, level translation, and relay or LED driver arrays where consistent switching voltage matters across channels. Collector current is rated 100mA maximum per transistor, with a collector-emitter breakdown of 50V. The 300mW total power budget (both transistors combined) sets the practical continuous current limit — at 50V rail, each transistor can dissipate roughly 150mW in free air, so derate when both channels run simultaneously at high current or elevated ambient temperature. Transition frequency of 250MHz is fast enough for 1–10 MHz switching regulators and logic-level signal inversion, though the pre-biased resistors add a few nanoseconds of turn-off delay compared to a bare transistor. For sub-microsecond switching, check the R1/Ciss time constant against your edge rate.
Package and marking — what to check on incoming inspection
The SC-74 (SOT-457) is a 6-lead package with a 1.5 mm body height — footprint compatible with the common SMT6 land pattern. ROHM marks the top side with a date-code and a lot identifier. The laser etch on a genuine part is crisp, with consistent font spacing across the batch. If you see re-sanded surfaces or a mark that looks re-stamped, the lot needs decap verification — the internal die bond-pad layout is a reliable tell.
Active status and supply posture
ROHS3 compliant.