Overview

The 2N3055 is a legendary complementary NPN silicon power transistor manufactured by ON Semiconductor and STMicroelectronics. Introduced originally by RCA in the 1960s, it is one of the most famous power semiconductors in history. Enclosed in a heavy-duty TO-3 metal can package, it offers high thermal dissipation and rugged reliability.

Supporting collector-emitter voltages up to 60 Volts60\text{ Volts}, continuous collector currents up to 15 Amps15\text{ Amps}, and a total power dissipation rating of 115 Watts115\text{ Watts} (at TC=25∘CT_C = 25^\circ\text{C}), the 2N3055 is widely used in high-power linear bench supplies, high-fidelity class-AB audio power amplifiers, motor speed controllers, and DC power switches. Its PNP complementary counterpart is the MJ2955.

Quick reference

Transistor TypeNPN Power Bipolar Junction Transistor
PackageTO-3 (Hermetic Metal Can — Case is connected to COLLECTOR)
Collector-Emitter Voltage (VCEOV_{CEO})60 V60\text{ V} max
Collector-Base Voltage (VCBOV_{CBO})100 V100\text{ V} max
Continuous Collector Current (ICI_C)15.0 A15.0\text{ A} continuous
Base Current (IBI_B)7.0 A7.0\text{ A} max
DC Current Gain (hFEh_{FE})20 to 70 at IC=4.0AI_C = 4.0\text{A} (hFE≥5h_{FE} \ge 5 at 10A10\text{A})
Transition Frequency (fTf_T)2.5 MHz2.5\text{ MHz} min
Total Power Dissipation (PDP_D)115 W115\text{ W} at TC=25∘CT_C = 25^\circ\text{C}

Pinout (TO-3 Metal Can Package)

Looking at the bottom pin side of the TO-3 metal can with pins pointing toward you:

text
               ┌─────────────────┐
               │    ( ( O ) )    │  Mounting Hole 1
               │                 │
               │   (1)     (2)   │
               │    B       E    │
               │                 │
               │    ( ( O ) )    │  Mounting Hole 2
               └─────────────────┘
           Metal Case = ( C ) COLLECTOR
PinNameDescription
1BASE (B)Base terminal (Thinner pin, off-center offset left)
2EMITTER (E)Emitter terminal (Thinner pin, off-center offset right)
CaseCOLLECTOR (C)Outer metal case and mounting holes (Collector terminal)
Warning

Metal Case Warning: Case is live Collector! The TO-3 metal outer case is internally tied directly to the Collector. When mounting a 2N3055 onto a metal heatsink, always use a mica or silicone insulating washer and non-conductive mounting shoulder bushings to prevent shorting the Collector to ground.

Specifications

ParameterSymbolMinTypMaxUnitConditions
Collector-Emitter Sustaining VoltageVCEO(sus)V_{CEO(sus)}60——VIC=200mA,IB=0I_C = 200\text{mA}, I_B = 0
DC Current Gain (IC=4AI_C=4\text{A})hFEh_{FE}20—70—VCE=4V,IC=4AV_{CE} = 4\text{V}, I_C = 4\text{A}
DC Current Gain (IC=10AI_C=10\text{A})hFEh_{FE}5———VCE=4V,IC=10AV_{CE} = 4\text{V}, I_C = 10\text{A}
Collector Saturation VoltsVCE(sat)V_{CE(sat)}—1.13.0VIC=10A,IB=3.3AI_C = 10\text{A}, I_B = 3.3\text{A}
Base-Emitter On VoltageVBE(on)V_{BE(on)}——1.8VVCE=4V,IC=4AV_{CE} = 4\text{V}, I_C = 4\text{A}

Common mistakes

  • Forgetting base drive requirements at high collector currents: At IC=10AI_C = 10\text{A}, hFEh_{FE} drops to 5-10, requiring a base current IB≥1AI_B \ge 1\text{A} to saturate. Always use a driver transistor (such as a TIP31C or BD139) to supply sufficient base drive.
  • Shorting collector to heatsink: Mounting the TO-3 case onto a grounded chassis without a mica insulator creates an immediate short circuit on the high-voltage supply rail.

Notes

  • 2N3055 vs MJ2955: 2N3055 is NPN; MJ2955 is its complementary PNP counterpart used in push-pull power output stages.

Assets & downloads