Pinout
NPN/PNP transistor (TO-92) pinout
Pins
- Flat (marked) face towards you, legs down — the same package comes in two pin orders:
- E – B – C from the left: 2N3904, 2N3906, 2N2222 / PN2222 (the American 2N family)
- C – B – E from the left: BC547, BC557, BC337, BC327 (the European BC family) — exactly mirrored
- The base is in the middle on both, so a swapped part still half-works (reversed, at a small fraction of its gain) — check the datasheet every time the part number changes
Specifications
| Example parts | NPN: 2N3904, 2N2222A, BC547; PNP: 2N3906, BC557 |
|---|---|
| Collector–emitter voltage | 2N3904 / 2N2222A: 40 V; BC547: 45 V (PNP versions: −40 / −45 V) |
| Collector current (max) | 2N3904: 200 mA; 2N2222A: 600 mA; BC547: 100 mA |
| DC current gain (hFE) | 2N3904: 100–300 at 10 mA; 2N2222A: 100–300 at 150 mA; BC547: 110–800 (A/B/C gain groups) |
| Power dissipation | 2N3904 / 2N2222A: 625 mW; BC547: 500 mW (TO-92, 25 °C) |
| Transition frequency | ≈ 300 MHz (2N3904, 2N2222A) |
| Base–emitter voltage (on) | ≈ 0.65–0.7 V |
| Pin order (flat face, legs down) | 2N family: E–B–C; BC family: C–B–E |
| Package | TO-92 |
