BD139 Datasheet | Next Electromics

BD139 NPN Power Transistor Technical Summary

Overview

The BD139 is a versatile NPN power transistor housed in a TO-126 (SOT32) plastic package. Designed for medium-power applications, this transistor offers a balance of current handling, voltage tolerance, and thermal performance. It is commonly used in amplification, switching, and linear regulation circuits due to its robust construction and reliable electrical characteristics.

The BD139 is part of a complementary pair with the BD140 PNP transistor, making it ideal for push-pull amplifier configurations. Its TO-126 package provides a good thermal dissipation capability while maintaining a compact footprint, suitable for both through-hole and some surface-mount applications with appropriate adapters.

Features

High Current Capability: Maximum collector current of 1.5 A for power applications.
Moderate Voltage Rating: Collector-emitter voltage (V_CEO) up to 80 V.
Good Power Dissipation: 12.5 W total power dissipation at 25°C ambient temperature.
Complementary Pair Available: Matched with BD140 PNP transistor for symmetrical circuits.
Low Saturation Voltage: Ensures efficient switching performance.
Wide Operating Temperature Range: -55°C to +150°C junction temperature range.
TO-126 Package: Robust plastic package with good thermal characteristics.

Applications

The BD139 finds use in a wide variety of electronic circuits, including:

Audio Amplifiers: Output stages in Class AB amplifiers and driver stages.
Power Regulation: Series pass elements in linear voltage regulators.
Switching Circuits: Medium-speed switching applications.
Motor Control: Driver stages for small DC motors.
General Purpose Amplification: Signal amplification in various electronic devices.
Complementary Symmetry Circuits: Paired with BD140 in push-pull configurations.

Electrical Characteristics

(All values at T_j = 25°C unless otherwise specified)

Absolute Maximum Ratings

Collector-Emitter Voltage (V_CEO): 80 V
Collector-Base Voltage (V_CBO): 100 V
Emitter-Base Voltage (V_EBO): 5 V
Collector Current (I_C): 1.5 A (continuous)
Base Current (I_B): 0.5 A
Total Power Dissipation (P_tot): 12.5 W at T_amb ≤ 25°C
Junction Temperature (T_j): -55°C to +150°C
Storage Temperature (T_stg): -55°C to +150°C

Thermal Characteristics

Thermal Resistance, Junction to Ambient (R_thJA): 83.3°C/W
Thermal Resistance, Junction to Case (R_thJC): 10°C/W

DC Current Gain (h_FE)

Minimum h_FE @ I_C = 0.5 A, V_CE = 2 V: 40
Typical h_FE @ I_C = 0.5 A, V_CE = 2 V: 100
Maximum h_FE @ I_C = 0.5 A, V_CE = 2 V: 250

Saturation Characteristics

Collector-Emitter Saturation Voltage (V_CE(sat)):
- 0.5 V max @ I_C = 0.5 A, I_B = 50 mA
- 0.75 V max @ I_C = 1 A, I_B = 100 mA
Base-Emitter Saturation Voltage (V_BE(sat)):
- 1.2 V max @ I_C = 0.5 A, I_B = 50 mA
- 1.5 V max @ I_C = 1 A, I_B = 100 mA

Package Information

TO-126 (SOT32) Package Dimensions

Package Type: Through-hole, plastic
Weight: Approximately 0.8 grams
Terminal Material: Tin-plated copper alloy
Mounting Style: Through-hole, vertical mounting
Flammability Rating: UL 94V-0

Mechanical Dimensions (in mm)

Total Height: 10.16 max
Body Length: 10.16 max
Body Width: 4.7 max
Lead Length: 19.05 nominal
Lead Diameter: 0.6 nominal
Lead Spacing: 5.08 between adjacent leads

Handling and Mounting Considerations

When working with the BD139 transistor, observe the following precautions:

Use appropriate heat sinking for power dissipation above 1 W
Maintain proper lead bending radius (minimum 1.5 mm from package body)
Avoid exceeding maximum junction temperature during soldering (260°C for 10 seconds max)
Ensure proper orientation when inserting into PCB (flat side indicates emitter lead)
Use anti-static precautions when handling