SILICON PNP POWER DARLINGTON TRANSISTOR# BD336 Technical Documentation
## 1. Application Scenarios
### Typical Use Cases
The BD336 is a versatile NPN bipolar junction transistor (BJT) primarily employed in medium-power amplification and switching applications . Common implementations include:
- Audio Amplification Stages : Used in Class AB push-pull configurations for output stages in audio amplifiers (5-30W range)
- Motor Drive Circuits : Suitable for DC motor control in appliances and automotive systems
- Voltage Regulation : Employed in series pass regulator circuits for stable power supply outputs
- LED Driver Systems : Current regulation for high-power LED arrays
- Relay and Solenoid Drivers : Switching inductive loads with appropriate protection
### Industry Applications
- Consumer Electronics : Audio systems, power supplies for home appliances
- Automotive Systems : Window motor controls, fan drivers, lighting circuits
- Industrial Control : Motor drives, solenoid actuators, power management
- Telecommunications : Power amplification in RF stages (up to 3MHz)
### Practical Advantages and Limitations
Advantages:
- High Current Capability : Continuous collector current up to 4A
- Good Power Handling : Maximum power dissipation of 36W
- Robust Construction : TO-126 package provides excellent thermal performance
- Wide Voltage Range : VCEO of 60V supports various circuit configurations
- Cost-Effective : Economical solution for medium-power applications
Limitations:
- Moderate Frequency Response : Limited to applications below 3MHz
- Thermal Management Required : Requires heatsinking for full power operation
- Beta Variation : Current gain (hFE) varies significantly with temperature and current
- Saturation Voltage : VCE(sat) of 1.5V may limit efficiency in low-voltage applications
## 2. Design Considerations
### Common Design Pitfalls and Solutions
Thermal Runaway
- Problem : Increasing temperature reduces VBE, increasing base current, creating positive feedback
- Solution : Implement emitter degeneration resistors and proper thermal management
Secondary Breakdown
- Problem : Localized heating at high voltage and current combinations
- Solution : Operate within safe operating area (SOA) limits, use derating factors
Inductive Load Switching
- Problem : Voltage spikes from inductive kickback can exceed VCEO
- Solution : Implement snubber circuits or flyback diodes
### Compatibility Issues with Other Components
Driver Circuit Compatibility
- Requires adequate base drive current (typically 100-400mA for full saturation)
- CMOS logic outputs may need buffer stages for proper drive capability
- Compatible with most op-amp outputs when used with current limiting resistors
Power Supply Considerations
- Ensure power supply can deliver required peak currents
- Decoupling capacitors essential for stable operation in amplifier circuits
- Consider inrush current requirements for motor starting applications
### PCB Layout Recommendations
Thermal Management
- Use generous copper pours connected to the collector tab
- Minimum 2oz copper thickness recommended for power traces
- Provide adequate clearance for heatsink mounting
Signal Integrity
- Keep base drive components close to the transistor
- Separate high-current collector paths from sensitive signal traces
- Use star grounding for power and signal grounds
Parasitic Reduction
- Minimize lead lengths in high-frequency applications
- Use bypass capacitors close to collector and emitter pins
- Implement proper RF grounding techniques for amplifier applications
## 3. Technical Specifications
### Key Parameter Explanations
Absolute Maximum Ratings
- VCEO : 60V (Collector-Emitter Voltage) - Maximum voltage between collector and emitter with base open
- IC : 4A (Collector Current) - Maximum continuous collector current
- PC : 36W (Power Dissipation) - Maximum power dissipation at TC = 25°C
