Product Overview
2N4921 NPN Silicon Medium-Power Transistor, 40 V 1 A 30 W, TO-126 / TO-225 Case, Pinout Printed on the Body
Condition
Unused new old stock (NOS). Markings legible: National Semiconductor logo, 2N4921, E C B. Sold each.
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Product Overview
National Semiconductor 2N4921: a JEDEC-registered NPN silicon power transistor for driver, amplifier and switching stages that need a 40 V, 1 A device in a bolt-down plastic case. National printed the lead legend E C B across the face under the part number, so the pinout reads straight off the part.
Key Features
- Type: NPN silicon bipolar power transistor
- VCEO 40 V, VCB 40 V, VEB 5.0 V
- Collector current 1.0 A continuous, 3.0 A peak
- Power dissipation 30 W at a 25 C case temperature
- DC current gain (hFE) 40 to 150 at 50 mA; 10 min at 1.0 A (VCE 1.0 V)
- Transition frequency (fT) 3.0 MHz min
- Package: TO-126 / TO-225 (Case 77) plastic, single mounting hole, three in-line leads
- Pinout: emitter, collector, base, left to right with the marked face toward you; the tab is common with the collector
Applications
- Replacing a 2N4921 in a driver or output stage of vintage audio, test and control gear
- Switching relay coils, solenoids, lamps and small motors at up to 1 A
- Pass element or error-amp driver in a hand-built linear supply
- Bench and hobby builds that want a medium-power NPN that bolts to a small heatsink
Frequently Asked Questions
Is the mounting tab live?
Yes. The tab is common with the collector, the center lead. On a grounded heatsink or chassis, mount it with an insulating washer and shoulder bushing.
A JEDEC 2N number was a shared contract: whichever maker built a 2N4921 built it to the same registered ratings, and this one carries National's logo. A drawing that calls for a 2N4921 never asked whose logo would be on it.
