Dual NPN common-base pair for sensor bias and buffering
The HN4C51J(TE85L,F) packs two NPN transistors in a common-base configuration inside a single SOT-753 package. The 100 MHz transition frequency keeps propagation delay low when shaping edges from a Hall switch or encoder output.
150°C junction and 300mW power ceiling
The 300 mW total power dissipation sets the thermal budget for both transistors combined — if one side drives a heavier load, the other side's dissipation must be backed off to stay under the package limit. Vce saturation is specified at 300 mV maximum at 1 mA base current and 10 mA collector current.
Active production, SC-74A package, tape-and-reel delivery
Toshiba lists the HN4C51J(TE85L,F) as Active and RoHS compliant.
PNP complement HN4A51J for push-pull sensor drive
The closest functional counterpart is the HN4A51J(TE85L,F), which is a dual PNP common-base transistor in the same SC-74A package with identical 120V Vceo, 100mA Ic, 300mW Pd, and 100 MHz fT ratings. The key difference: the HN4C51J uses NPN devices, the HN4A51J uses PNP. If your sensor interface requires a push-pull or complementary output stage, pairing the two in the same package footprint keeps the board layout symmetrical.