BD909
BD909 NPN Power Transistor Technical Summary
Overview
The BD909 is a silicon epitaxial-base NPN power transistor designed for high-power amplification and switching applications. Packaged in the industry-standard TO-220 plastic package, this device offers excellent thermal performance and power dissipation capabilities. The BD909 is part of a complementary pair with the BD911 PNP transistor, making it ideal for push-pull amplifier configurations.
This transistor is characterized by its high current capability, good saturation characteristics, and robust construction suitable for demanding industrial and consumer applications. The epitaxial-base construction ensures high switching speeds while maintaining thermal stability.
Key Features
- High collector current capability (IC = 12A continuous)
- Excellent power dissipation (80W at 25°C case temperature)
- Low collector-emitter saturation voltage
- Complementary pair available with BD911 (PNP)
- High current gain bandwidth product
- TO-220 package for optimal thermal performance
- Designed for linear and switching applications
- High voltage capability (VCEO = 80V)
Applications
The BD909 finds use in a wide range of power electronics applications:
Power Amplification
- Audio power amplifiers (complementary output stages)
- Servo motor drivers
- Linear power supplies
Switching Applications
- DC-DC converters
- Power supply regulators
- Motor control circuits
- Relay drivers
- Inductive load switching
Industrial Systems
- Power management systems
- UPS (Uninterruptible Power Supplies)
- Welding equipment
- Industrial automation controls
Electrical Characteristics
The following tables detail the key electrical specifications of the BD909 transistor:
Absolute Maximum Ratings
| Parameter | Symbol | Value | Unit |
|---|---|---|---|
| Collector-Emitter Voltage | VCEO | 80 | V |
| Collector-Base Voltage | VCBO | 100 | V |
| Emitter-Base Voltage | VEBO | 5 | V |
| Collector Current (Continuous) | IC | 12 | A |
| Base Current | IB | 4 | A |
| Total Power Dissipation at Tc=25°C | PTOT | 80 | W |
| Junction Temperature | TJ | 150 | °C |
| Storage Temperature Range | TSTG | -65 to +150 | °C |
Thermal Characteristics
| Parameter | Symbol | Value | Unit |
|---|---|---|---|
| Thermal Resistance, Junction to Case | RthJC | 1.56 | °C/W |
| Thermal Resistance, Junction to Ambient | RthJA | 62.5 | °C/W |
Electrical Characteristics (TA=25°C unless otherwise specified)
| Parameter | Symbol | Test Conditions | Min | Typ | Max | Unit |
|---|---|---|---|---|---|---|
| DC Current Gain | hFE | VCE=2V, IC=3A | 40 | - | 140 | - |
| Collector-Emitter Saturation Voltage | VCE(sat) | IC=6A, IB=0.6A | - | 0.5 | 1.0 | V |
| Base-Emitter Saturation Voltage | VBE(sat) | IC=6A, IB=0.6A | - | 1.2 | 2.0 | V |
| Transition Frequency | fT | VCE=5V, IC=0.5A, f=1MHz | 3 | - | - | MHz |
Package Information
The BD909 is available in the TO-220 plastic package, which provides excellent thermal performance and mechanical strength. The package dimensions and pin configuration are as follows:
TO-220 Package Dimensions
- Total height: 16.0mm max
- Body width: 10.0mm max
- Body length: 14.5mm max
- Lead length: 19.0mm min
- Lead spacing: 2.54mm (0.1 inch)
- Mounting hole diameter: 3.5mm
Pin Configuration
- Base (B): Control terminal for transistor operation
- Collector (C): Main current carrying terminal (connected to tab)
- Emitter (E): Current output terminal
The TO-220 package features an exposed metal tab that serves as the collector terminal and provides
