MJE3055T — 60V 10A Power NPN BJT (Plastic TO-220 2N3055 Equivalent)

Overview

The MJE3055T is a 60V 10A silicon power NPN bipolar junction transistor manufactured by onsemi and STMicroelectronics. Housed in a through-hole TO-220AB package, it was engineered as the direct plastic-package equivalent of the historic 2N3055 metal TO-3 diamond-case power transistor.

Providing a collector-emitter breakdown voltage ( $V_{CEO}$ ) of $60\text{V}$ , a high continuous collector current rating of $10.0\text{A}$ , and a massive power dissipation capability of $75\text{ Watts}$ at $T_C = 25^\circ\text{C}$ ( $\theta_{JC} = 1.67^\circ\text{C/W}$ ), the MJE3055T delivers the rugged performance of a 2N3055 in a modern, PCB-friendly form factor. Paired with its PNP complement MJE2955T, it is the industry standard for linear laboratory DC bench power supplies (series-pass regulators), high-power audio amplifiers (30W–80W Class AB/B outputs), heavy DC motor speed controllers, and magnetic actuator drivers.

Quick reference


Transistor Type	High-Power Silicon NPN Power BJT
Package	TO-220AB (3-pin through-hole)
Collector-Emitter Voltage ( $V_{CEO}$ )	$60\text{ V}$ max
Collector-Base Voltage ( $V_{CBO}$ )	$70\text{ V}$ max
Continuous Collector Current ( $I_C$ )	$10.0\text{ A}$ max
Base Current ( $I_B$ )	$6.0\text{ A}$ max
DC Current Gain ( $h_{FE}$ )	$20$ to $100$ ( $I_C = 4.0\text{A}, V_{CE} = 4.0\text{V}$ ) / $\ge 5$ at $10\text{A}$
Collector Saturation ( $V_{CE(sat)}$ )	$1.1\text{ V}$ max ( $I_C = 4.0\text{A}, I_B = 400\text{mA}$ ) / $3.0\text{V}$ at $10\text{A}$
Total Power Dissipation ( $P_D$ )	$75\text{ Watts}$ ( $T_C = 25^\circ\text{C}$ with heatsink) / $1.75\text{ W}$ free air
Transition Frequency ( $f_T$ )	$2.0\text{ MHz}$ min
Thermal Resistance ( $\theta_{JC}$ )	$1.67^\circ\text{C/W}$ (Junction-to-Case)
Complementary PNP Pair	MJE2955T (60V 10A PNP)

Pinout (TO-220AB Package - B-C-E Standard)

Looking at the front labeled face with leads pointing downward:

text

        ┌──────────────┐
        │  O  [Metal]  │ ── Tab is internally connected to Pin 2 (Collector)
        ├──────────────┤
        │   MJE3055T   │
        └─┬────┬────┬──┘
          1    2    3
          B    C    E

Pin	Name	Type	Description
1	`BASE`	Base Input	Base control input (Driven with base current via driver transistor)
2 (Tab)	`COLLECTOR`	Power Collector	Collector terminal (Internally connected to metal mounting tab)
3	`EMITTER`	Power Emitter	Emitter output (Connect to output rail or current-sense resistor)

Specifications

Parameter	Symbol	Min	Typ	Max	Unit	Conditions
Collector-Emitter Breakdown	$V_{(BR)CEO}$	60	—	—	V	$I_C = 30\text{mA}, I_B = 0$
Collector-Base Breakdown	$V_{(BR)CBO}$	70	—	—	V	$I_C = 1.0\text{mA}, I_E = 0$
Emitter-Base Breakdown	$V_{(BR)EBO}$	5.0	—	—	V	$I_E = 1.0\text{mA}, I_C = 0$
Collector Cutoff Current	$I_{CEO}$	—	—	700	µA	$V_{CE} = 30\text{V}, I_B = 0$
DC Current Gain ( $h_{FE}$ )	$h_{FE}$	20	—	100	—	$I_C = 4.0\text{A}, V_{CE} = 4.0\text{V}$
DC Current Gain ( $h_{FE}$ )	$h_{FE}$	5	—	—	—	$I_C = 10.0\text{A}, V_{CE} = 4.0\text{V}$
Collector Saturation Voltage	$V_{CE(sat)}$	—	—	1.1	V	$I_C = 4.0\text{A}, I_B = 400\text{mA}$
Collector Saturation Voltage	$V_{CE(sat)}$	—	—	3.0	V	$I_C = 10.0\text{A}, I_B = 3.3\text{A}$
Base-Emitter On Voltage	$V_{BE(on)}$	—	—	1.8	V	$I_C = 4.0\text{A}, V_{CE} = 4.0\text{V}$

Typical Application: 0–30V 5A Linear Bench Power Supply Series-Pass Stage

text

      Unregulated +35V DC Filtered Rail (from Transformer + Bridge)
                                  │
                           [Pin 2: COLLECTOR]
                              MJE3055T
  Driver Transistor        [Pin 1: BASE]
  (e.g. BD139 / TIP31C)           │
          │                       │
          └───────────────────────┤
                                  │
                           [Pin 3: EMITTER]
                                  │
                                  ├───[ 0.1Ω 5W Current Sense Resistor ]───► Regulated +0-30V Output (Up to 5A)
                                  │
                                 GND ──────────────────────────────────────► Power Supply Return (0V)

Comparison: MJE3055T vs 2N3055 vs TIP3055

Parameter	MJE3055T	2N3055	TIP3055
Package	TO-220AB (Plastic)	TO-3 (Metal Diamond)	TO-247 / TO-218 (Large Plastic)
$V_{CEO}$ Voltage	$60\text{ V}$	$60\text{ V}$	$60\text{ V}$
Max Current ( $I_C$ )	$10\text{ A}$	$15\text{ A}$	$15\text{ A}$
Power Dissipation ( $P_D$ )	$75\text{ W}$	$115\text{ W}$	$90\text{ W}$
Mounting Style	Single Screw on PCB	2 Screws + Sockets	Single Screw Heavy

Common mistakes

Underestimating base current requirements at high loads: With $h_{FE} \approx 20$ at $4\text{A}$ , the base requires $I_B \approx 200\text{mA} \dots 400\text{mA}$ . The base cannot be driven directly by an op-amp or microcontroller; always use a medium-power pre-driver transistor (such as the BD139 or TIP31C) in a Darlington or Sziklai pair configuration.
Operating without a substantial heatsink: At $5\text{A}$ load with $10\text{V}$ drop across the regulator, power dissipation is $P = 50\text{ Watts}$ . A heavy extruded aluminum heatsink with thermal compound and silicone insulator is essential.

Notes

Suffix Guide: MJE3055T is standard TO-220; MJE3055TG denotes lead-free RoHS compliance; MJE2955T is the complementary PNP partner.