AC Solid State Relay # CPC1965G Solid State Relay Technical Documentation
Manufacturer : CLARE (now part of IXYS, a Littelfuse Company)
## 1. Application Scenarios
### Typical Use Cases
The CPC1965G is a 1.5A, 400V optically isolated solid state relay (SSR) designed for AC load switching applications. Typical use cases include:
- Industrial Control Systems : PLC output modules, motor starters, and contactor replacements
- HVAC Equipment : Compressor controls, fan speed regulation, and heater control
- Lighting Systems : Dimming circuits, stage lighting control, and architectural lighting
- Medical Equipment : Patient isolation barriers, equipment power control
- Home Appliances : Smart home controllers, washing machine motor controls, dishwasher heaters
### Industry Applications
- Manufacturing : Machine tool controls, conveyor systems, packaging equipment
- Energy Management : Smart grid applications, power distribution control
- Building Automation : HVAC zone controls, lighting management systems
- Transportation : Railway signaling, electric vehicle charging systems
- Telecommunications : Network equipment power switching, backup power control
### Practical Advantages
- High Reliability : No moving parts, eliminating mechanical wear and contact bounce
- Fast Switching : Typical turn-on time of 0.5ms, turn-off time of 0.1ms
- Noise-Free Operation : Zero voltage crossing reduces EMI and prevents current surges
- Long Life Expectancy : >10^8 operations at rated load
- High Isolation : 3750Vrms input-to-output isolation
- Compact Package : DIP-6 package saves board space
### Limitations
- Heat Dissipation : Requires proper thermal management at maximum current ratings
- Voltage Drop : Typical 1.6V forward voltage reduces efficiency compared to mechanical relays
- Leakage Current : 5mA maximum off-state leakage current
- Cost Consideration : Higher initial cost than equivalent electromechanical relays
- Surge Current : Limited surge current handling capability (10A for one cycle)
## 2. Design Considerations
### Common Design Pitfalls and Solutions
Thermal Management Issues
- *Pitfall*: Overheating due to inadequate heat sinking
- *Solution*: Use proper heat sinks and ensure adequate airflow. Calculate thermal resistance (RθJA = 60°C/W) and derate current above 40°C ambient temperature
Inductive Load Switching
- *Pitfall*: Voltage spikes when switching inductive loads
- *Solution*: Implement snubber circuits (typically 100Ω resistor in series with 0.1μF capacitor) across output terminals
Input Circuit Design
- *Pitfall*: Insufficient input current for reliable operation
- *Solution*: Ensure minimum 5mA input current with proper current-limiting resistor calculation
### Compatibility Issues
Microcontroller Interfaces
- The 1.2V minimum trigger voltage makes the CPC1965G compatible with most 3.3V and 5V microcontroller outputs
- When using low-current microcontroller pins, consider adding a buffer transistor to ensure adequate drive current
Load Compatibility
- Compatible with resistive, inductive, and capacitive loads within specified ratings
- For highly capacitive loads, add series resistance to limit inrush current
- For motor loads, derate current by 40-60% to handle starting currents
### PCB Layout Recommendations
Thermal Design
- Use large copper areas for heat dissipation
- Include thermal vias when using multilayer boards
- Position away from other heat-generating components
High Voltage Considerations
- Maintain minimum 8mm creepage distance between input and output circuits
- Use solder mask to prevent contamination and tracking
- Implement proper grounding and shielding for noise-sensitive applications
Signal Integrity
- Keep
