Suppressor# Technical Documentation: 15SMC20AT3 Transient Voltage Suppressor
Manufacturer : ON Semiconductor
Component Type : 15kW Transient Voltage Suppressor (TVS) Diode
Package : SMC (DO-214AB)
## 1. Application Scenarios
### Typical Use Cases
The 15SMC20AT3 is primarily employed for robust transient voltage protection in electronic circuits where high-energy surges are anticipated. Typical implementations include:
- AC/DC Power Input Protection : Installed at power entry points to suppress lightning-induced transients and inductive load switching spikes
- Telecommunications Line Protection : Used in DSL/VDSL modems, PBX systems, and network equipment to protect against lightning surges on communication lines
- Industrial Control Systems : Guards PLCs, motor drives, and sensor interfaces against voltage transients from relay/contactor switching and ESD events
- Automotive Electronics : Protects ECUs, infotainment systems, and charging interfaces from load dump and jump-start voltage spikes
### Industry Applications
Telecommunications Infrastructure
- Central office equipment protection
- Base station power and signal line protection
- Fiber optic network terminal equipment
Industrial Automation
- Motor drive input protection
- PLC I/O module safeguarding
- Process control instrumentation
Consumer Electronics
- High-end audio/video equipment
- Gaming console power protection
- Smart home controller units
Renewable Energy Systems
- Solar inverter DC input protection
- Wind turbine control systems
- Battery management systems
### Practical Advantages and Limitations
Advantages:
- High Surge Capability : Withstands 15kW peak pulse power (10/1000μs waveform)
- Fast Response Time : Typically <1.0ps reaction to transient events
- Low Clamping Ratio : Provides effective voltage limitation during surge events
- Robust Construction : Hermetically sealed package ensures reliability in harsh environments
- Wide Temperature Range : Operational from -65°C to +150°C
Limitations:
- Parasitic Capacitance : ~1500pF typical may affect high-frequency signal integrity
- Physical Size : SMC package requires adequate PCB space
- Standby Power : Minimal leakage current (~5μA maximum) present during normal operation
- Voltage Derating : Requires careful consideration at elevated temperatures
## 2. Design Considerations
### Common Design Pitfalls and Solutions
Pitfall 1: Inadequate Current Handling
- Issue : Underestimating surge current requirements leading to TVS failure
- Solution : Calculate maximum expected surge current using Ipp = Ppp / Vc, ensuring the 15SMC20AT3's 75A (typical) capability meets requirements
Pitfall 2: Thermal Management Neglect
- Issue : Overheating during repeated surge events causing premature degradation
- Solution : Implement proper thermal relief in PCB layout and consider heatsinking for high-repetition applications
Pitfall 3: Voltage Margin Errors
- Issue : Selecting VRWM too close to operating voltage, causing unnecessary activation
- Solution : Maintain 10-20% margin between maximum operating voltage and 20V VRWM rating
### Compatibility Issues with Other Components
Protection Coordination:
- Ensure proper coordination with upstream fuses/circuit breakers
- Coordinate with lower-level protection devices (ESD diodes) to create staged protection scheme
Signal Integrity Considerations:
- High capacitance may affect high-speed data lines (>10MHz)
- For sensitive analog circuits, consider lower-capacitance TVS alternatives
Power Supply Interactions:
- May interact with bulk capacitors during surge events
- Ensure power supply can handle the additional load during clamping
### PCB Layout Recommendations
Placement Strategy:
- Position as close as possible
