0.625W General Purpose PNP Plastic Leaded Transistor. 50V Vceo, 0.050A Ic, 250# 2N5087 NPN Silicon Transistor Technical Documentation
Manufacturer : SENTRY
## 1. Application Scenarios
### Typical Use Cases
The 2N5087 is a general-purpose NPN silicon bipolar junction transistor (BJT) primarily employed in low-power amplification and switching applications. Its high current gain (hFE) makes it particularly suitable for:
- Audio Preamplification : Excellent for microphone preamps, tone control circuits, and audio signal conditioning due to low noise characteristics
- Signal Amplification : Small-signal amplification in the 1-100 MHz range for RF and intermediate frequency stages
- Impedance Buffering : Effective as an emitter follower for impedance matching between high-impedance sources and low-impedance loads
- Switching Circuits : Moderate-speed switching applications in digital logic interfaces and relay drivers
- Oscillator Circuits : LC and RC oscillator designs requiring stable gain characteristics
### Industry Applications
- Consumer Electronics : Audio equipment, remote controls, and portable devices
- Telecommunications : RF front-end circuits, modem interfaces, and telephone line interfaces
- Industrial Control : Sensor interfaces, process control systems, and monitoring equipment
- Automotive Electronics : Non-critical sensor conditioning and entertainment systems
- Medical Devices : Low-power patient monitoring equipment and diagnostic instruments
### Practical Advantages and Limitations
Advantages:
- High DC current gain (typically 350-800) reduces required base drive current
- Low noise figure makes it ideal for sensitive amplification stages
- Wide operating temperature range (-65°C to +200°C) ensures reliability
- Good frequency response suitable for many RF applications
- Cost-effective solution for general-purpose amplification
Limitations:
- Limited power handling capability (625 mW maximum)
- Moderate switching speed not suitable for high-frequency digital applications
- Voltage limitations restrict use in high-voltage circuits
- Temperature-dependent gain variations require compensation in precision circuits
- Not optimized for high-current switching applications
## 2. Design Considerations
### Common Design Pitfalls and Solutions
Thermal Runaway
- Problem : High current gain can lead to thermal instability
- Solution : Implement emitter degeneration resistors (typically 10-100Ω) and ensure proper heat sinking
Gain Bandwidth Product Limitations
- Problem : Frequency response degradation at higher gains
- Solution : Use cascode configurations or select alternative transistors for applications above 100 MHz
Saturation Voltage Concerns
- Problem : Higher VCE(sat) compared to modern alternatives
- Solution : Ensure adequate base drive current and consider Darlington pairs for lower saturation requirements
### Compatibility Issues with Other Components
Biasing Circuits
- The 2N5087's high beta requires careful bias network design to prevent thermal runaway
- Voltage divider biasing with temperature compensation recommended
Load Matching
- Output impedance typically 1-10 kΩ requires proper matching with subsequent stages
- Use impedance transformation networks when driving low-impedance loads
Power Supply Considerations
- Maximum VCEO of 50V limits supply voltage choices
- Ensure power supply ripple and transients remain within safe operating area
### PCB Layout Recommendations
Thermal Management
- Provide adequate copper area around the transistor package for heat dissipation
- Use thermal vias when mounting on multilayer boards
- Maintain minimum 2mm clearance from other heat-generating components
Signal Integrity
- Keep input and output traces separated to prevent feedback and oscillation
- Use ground planes beneath RF circuits to minimize parasitic capacitance
- Implement proper decoupling capacitors (100nF ceramic) close to collector pin
Assembly Considerations
- Follow ESD protection protocols during handling and installation
- Ensure proper lead forming to avoid stress on semiconductor junctions
- Use recommended soldering profiles: 260°C maximum for 10 seconds
## 3. Technical Specifications
