Axial−Lead Fast−Recovery Rectifiers # 1N4935RLG Fast Switching Rectifier - Technical Documentation
Manufacturer : ON Semiconductor
## 1. Application Scenarios
### Typical Use Cases
The 1N4935RLG is a fast recovery rectifier diode specifically designed for high-frequency switching applications. Primary use cases include:
Power Supply Circuits
- Switch-mode power supply (SMPS) output rectification
- Flyback converter secondary-side rectification
- Forward converter applications
- DC-DC converter circuits
Protection Circuits
- Reverse polarity protection
- Freewheeling diode in inductive load circuits
- Snubber circuits for voltage spike suppression
- Clamping applications in power electronics
High-Frequency Applications
- RF detection circuits
- High-speed switching up to 200 kHz
- Pulse width modulation (PWM) circuits
### Industry Applications
Consumer Electronics
- LCD/LED television power supplies
- Computer power supplies (desktop and laptop)
- Gaming console power management
- Mobile device charging circuits
Industrial Systems
- Motor drive circuits
- Industrial power supplies
- Welding equipment
- UPS systems
Automotive Electronics
- DC-DC converters in automotive systems
- Power management modules
- LED lighting drivers
- Battery charging systems
### Practical Advantages and Limitations
Advantages
- Fast Recovery Time : 200 ns maximum reverse recovery time enables efficient high-frequency operation
- Low Forward Voltage : 1.0V maximum at 1.0A reduces power losses
- High Surge Current Capability : 30A peak surge current provides robust transient protection
- Glass Passivation : Ensures stable performance and reliability
- Compact DO-41 Package : Standard package for easy integration
Limitations
- Voltage Rating : 200V maximum repetitive reverse voltage limits high-voltage applications
- Current Handling : 1.0A average rectified current may require paralleling for higher current applications
- Temperature Sensitivity : Performance degrades at elevated temperatures above 150°C
- Switching Losses : While fast, still generates switching losses at very high frequencies (>500 kHz)
## 2. Design Considerations
### Common Design Pitfalls and Solutions
Thermal Management Issues
- Pitfall : Inadequate heat sinking leading to thermal runaway
- Solution : Implement proper PCB copper area (minimum 1.5 cm² per lead) and consider heatsinking for currents above 500mA
Voltage Spikes and Transients
- Pitfall : Voltage overshoot exceeding maximum ratings during switching
- Solution : Implement RC snubber circuits and ensure proper layout to minimize parasitic inductance
Reverse Recovery Current
- Pitfall : Excessive reverse recovery current causing EMI and efficiency losses
- Solution : Ensure operating frequency is within specified limits and consider soft-switching techniques
### Compatibility Issues with Other Components
MOSFET/IGBT Compatibility
- Ensure diode recovery characteristics match switching device capabilities
- Avoid pairing with ultra-fast MOSFETs that may require faster recovery diodes
Capacitor Selection
- Compatible with ceramic, electrolytic, and film capacitors
- Ensure capacitor ESR and ripple current ratings match diode switching characteristics
Inductive Components
- Works well with various inductor types
- Consider saturation current and core losses in conjunction with diode performance
### PCB Layout Recommendations
Power Path Layout
- Keep diode traces short and wide (minimum 40 mil width for 1A current)
- Place input/output capacitors close to diode terminals
- Use ground planes for improved thermal dissipation
Thermal Management
- Provide adequate copper area around diode leads
- Consider thermal vias for multilayer boards
- Maintain minimum 2mm clearance from heat-sensitive components
EMI Considerations
- Route high di/dt loops away from sensitive analog circuits
- Implement proper grounding techniques
- Use
