Home » Component data » Transistor data » this page
2N5551 Transistor Data
Key transistor data for the 2N5551 transistor including key electrical parameters, pinout, package type and many other key transistor datasheet details.
The 2N5551 is a high-voltage NPN bipolar junction transistor designed for general-purpose amplification and switching, offering a collector-emitter voltage rating of up to 160 V.
The 2N5551 also provides a moderate continuous collector current of 600 mA and a transition frequency around 100 MHz, making it suitable for low-power high-voltage signal applications.
Key details and performance parameters for the 2N5551 transistor.
| 2N5551 transistor datasheet parameters & data |
|
|---|---|
| Parameters | Details |
| Transistor type | NPN high voltage transistor |
| Package type | TO92 |
| VCBO max (V) | 180V |
| VCEO max (V) | 160V |
| VEBOmax (V) | 6V |
| VCEsat (V) | 0.15V max for IC = 10mA and IB = 1mA, 0.20V max for IC = 50mA and IB = 5 mA |
| IC max (mA) | 600mA |
| TJ Max °C | -55 - +150°C |
| PTOT mW | 625mW |
| fT min (MHz) | 100MHz minimum 300MHz max |
| Collector base capacitanceCCBO | 6pF |
| hfe | 80 min for IC = 1mA, 80 min and 250mx for IC = 10mA, and 30 min for IC = 50mA |
| Similar / equivalents | |
Outline & pinout:
Explanation of transistor parameters
| Parameter | Explanation |
|---|---|
| VCBO Max | Maximum collector-base voltage with emitter open circuit . |
| VCEO Max | Maximum collector-emitter voltage with base open circuit. |
| VEBO Max | Maximum emitter-base voltage with collector open circuit. |
| VCEsat (included where applicable) | The voltage drop across the collector-emitter when the transistor is fully saturated (acting as a closed switch). |
| IC Max | Maximum collector current. |
| Parameter | Explanation |
|---|---|
| TJ | Maximum junction temperature. |
| PTOT Max | Maximum device dissipation normally in free air at 25°C unless other conditions indicated. |
| fT Min | Minimum cutoff frequency at which the current gain in a common emitter circuit falls to unity. |
| COB Max | Maximum collector capacitane, normally measured with emitter open circuit. |
| hFE | DC current gain for HFE at IC. [Note hfe is the small signal gain and although this may be slightly different, the transistor current gain will vary considerably from ne transistor to the next of the same type.] |
| PTOT Max | Maximum device dissipation normally in free air at 25°C unless other conditions indicated. |
These are the main transistor parameters that have been included in our list. There are others, but these help quantify the main elements of the performance of the transistor.
Please note, that the data given is the best estimate we can give within a tabulated summary of this nature. Parameters also vary between manufacturers. Electronics Notes cannot accept any responsibility for errors, inaccuracies, etc, although we do endevaour to ensure the data is as accurate as possible.
Notes and supplementary information
• Availability & sources
The 2N5551 is available from a number of stockists and electronic component distributors many of which are given in the table below.
2N5551 Component Distributor, Stock and Pricing
• Notable features
The 2N5551 is a widely used NPN silicon bipolar junction transistor in a TO-92 package, prized for its high voltage capability, excellent gain linearity, and reliability in small-signal and medium-power applications.
High Collector-Emitter Voltage : VCEO = 160 V, one of the highest in the TO-92 NPN family.
Good Current Gain : hFE 80–250 but with some variations between manufacturers, with excellent linearity across a wide current range (0.1 mA to 50 mA).
Low Noise Performance : Noise figure typically <5 dB at 1 kHz, making it suitable for sensitive audio and sensor preamps.
High Transition Frequency : fT minimum 100 MHz (typical maximum figure of 300 MHz), enabling use in RF amplifiers up to VHF.
Medium Power Capability : Continuous collector current 600 mA, power dissipation 625 mW (TO-92), ideal for drivers and small amplifiers.
Low Saturation Voltage : VCE(sat) ≤ 0.2 V at 50 mA, great for efficient switching.
Complementary Pair : Perfect match with 2N5401 PNP for push-pull and complementary symmetry designs.
Cost-Effective and Ubiquitous : Industry-standard part, still in full production and available from multiple manufacturers.
• Typical applications summary
| Application Category | Typical Use Case | Device Feature Utilised |
|---|---|---|
| Audio Preamplifiers | Microphone and phono preamps, tone controls. | Low noise, high gain linearity, and complementary pairing with 2N5401. |
| High-Voltage Switching | Relay drivers, LED strips, and solenoid control up to 150 V. | 160 V VCEO and low VCE(sat) for efficient, cool-running switches. |
| RF & IF Amplifiers | VHF tuners, signal boosters, amateur radio preamps. | 100–300 MHz fT and good gain at radio frequencies. |
| Signal Processing | Active filters, oscillators, and waveform generators. | Excellent hFE linearity and low distortion. |
| General Purpose | Hobby projects, educational kits, and prototype circuits. | Versatile specs, low cost, and universal availability. |
• 2N5551 vs BC547 – Side-by-Side Comparison
A practical head-to-head comparison of the two most popular small-signal NPN transistors (BC547 data refers to the common BC547B/BC547C variants).
| Parameter | 2N5551 | BC547 (B/C) | Winner / Better for… |
|---|---|---|---|
| Type / Package | NPN Silicon – TO-92 | NPN Silicon – TO-92 | Tie |
| VCEO (max) | 160 V (180 V some) | 45 V | 2N5551 – high-voltage circuits |
| Collector Current (IC max) | 600 mA | 100 mA | 2N5551 – 6× higher current |
| Power Dissipation (Pd) | 625 mW | 500 mW | 2N5551 |
| Current Gain (hFE) | 80–250 (very linear) | B: 200–450 / C: 400–800 | BC547C for very high gain |
| Transition Frequency (fT) | 100 MHz min, typ. 300 MHz | ~300 MHz typical | Tie – both excellent to VHF |
| Noise Figure (1 kHz) | ~2–4 dB | ~2–5 dB | 2N5551 (slightly quieter) |
| VCE(sat) @ 50 mA | ≤ 0.2 V | ≤ 0.25 V | 2N5551 |
| Complementary PNP | 2N5401 (160 V) | BC557 (45 V) | 2N5551 + 2N5401 for high-voltage push-pull |
| Price (2025, 1k qty) | ~0.03–0.05 USD | ~0.015–0.03 USD | BC547 – cheaper |
• Quick Selection Guide 2N5551 vs BC557
| Use Case | Recommended | Why |
|---|---|---|
| General low-voltage audio / preamp | BC547 | Higher gain, lower cost |
| High voltage (>50–150 V supplies | 2N5551 | Only one that can handle it in TO-92 |
| Driving relays/LEDs >100 mA | 2N5551 | 600 mA vs 100 mA |
| Push-pull audio up to ±70 V | 2N5551 + 2N5401 | Matching 160 V complementary pair |
| Hobby / learning / bulk use | BC547 | Cheapest and does 95 % of jobs |
Written by Ian Poole .
Experienced electronics engineer and author.
Return to Component Data menu . . .
