Why this dual pre-biased part exists
The Toshiba RN4981FE,LXHF(CT packs one NPN and one PNP pre-biased transistor into a single SOT-563 package. Each transistor has its own 4.7kΩ base resistor (R1) and 4.7kΩ emitter-base resistor (R2) built in — no external bias network needed.
Automotive qualification — what it means for sourcing
Ratings that drive the fit decision
Collector-emitter breakdown is 50V minimum, which gives comfortable margin on a 12V automotive rail and still covers 24V systems with derating. Maximum collector current is 100mA per transistor — sized for relay drivers, solenoid pre-drivers, and logic-level signal inversion, not power switching. The 300mV saturation voltage at 250µA base and 5mA collector is tight enough to keep dissipation low in a SOT-563 package rated for 100mW total power. Transition frequency is 250MHz for the NPN side and 200MHz for the PNP, so switching up to a few MHz is fine; above that the gain roll-off starts to matter.
The RN4981FE comes in a SOT-563 package (also listed as SOT-666) with the supplier device code ES6. It is a surface-mount, six-lead package roughly 1.6mm x 1.6mm — small enough that hand-soldering is tricky; a hot-air rework station or reflow profile is the practical assembly method. The land pattern follows the standard SOT-563 footprint in the IPC-7351B nominal set.