2N6427 NPN Darlington Transistor

The 2N6427 is an NPN Darlington transistor: two BJTs cascaded internally so the emitter current of the first drives the base of the second, multiplying the overall current gain far beyond what a single transistor can deliver. It is housed in a TO-92 package and rated for collector currents up to 1.0A.

Because the effective hFE runs into the thousands, the 2N6427 can be switched fully on with only a tiny base current — useful for driving relays, solenoids, motors, or LED arrays directly from a microcontroller or logic-level output without an extra driver stage. Its 40V VCEO/VCBO rating keeps it in the “low voltage, high gain” category rather than a power-switching device for mains-adjacent work.

1. Darlington-pair construction for extremely high current gain
2. Collector current rating to 1.0A
3. 40V collector-emitter and collector-base voltage
4. 625mW power dissipation, TO-92 package
5. Low-cost single-package alternative to two discrete transistors
6. 12V emitter-base voltage rating
7. 7pF output capacitance, 15pF input capacitance
8. -55°C to +150°C junction temperature range