4-Pin SOP OptoMOS Relays # CPC1135NTR Solid State Relay Technical Documentation
Manufacturer : CLARE (IXYS Integrated Circuits Division)
Component Type : Photovoltaic MOSFET Driver Solid State Relay
## 1. Application Scenarios
### Typical Use Cases
The CPC1135NTR is primarily employed in applications requiring galvanic isolation between control circuits and power circuits. Its photovoltaic MOSFET driver technology makes it particularly suitable for:
- Low Power Switching : AC/DC load switching up to 100mA continuous current
- Battery-Powered Systems : Ultra-low power consumption (typical 0.5mA input current) enables extended battery life
- Medical Equipment : Patient-isolated circuits, diagnostic equipment interfaces
- Test and Measurement : Instrumentation switching, signal routing applications
- Industrial Control : PLC output modules, sensor interfaces, small motor control
### Industry Applications
Medical Electronics
- Patient monitoring equipment isolation barriers
- Medical diagnostic instrument switching
- Portable medical device power management
- Isolation in therapeutic equipment
Industrial Automation
- PLC digital output modules
- Process control system interfaces
- Safety interlock circuits
- Small motor and solenoid drivers
Telecommunications
- Line card switching circuits
- Network equipment power management
- Signal routing and isolation
- Backup battery switching
Consumer Electronics
- Smart home device control
- Battery management systems
- Power sequencing circuits
- Audio equipment switching
### Practical Advantages and Limitations
Advantages:
- High Isolation : 1500Vrms input-to-output isolation rating
- Low Power Operation : 0.5mA typical input current enables battery operation
- Fast Switching : Typical turn-on time of 0.15ms, turn-off time of 0.02ms
- No EMI Generation : Zero-voltage turn-on eliminates switching transients
- Long Lifespan : Solid-state construction, no moving parts or contacts to wear out
- Small Footprint : SMT package (4-SOP) saves board space
Limitations:
- Current Handling : Limited to 100mA continuous output current
- Voltage Drop : Typical 10Ω on-resistance creates voltage drop at higher currents
- Thermal Considerations : Requires proper heat dissipation at maximum current
- Cost : Higher per-channel cost compared to electromechanical relays for simple applications
## 2. Design Considerations
### Common Design Pitfalls and Solutions
Pitfall 1: Inadequate Heat Management
- Problem : Overheating when operating near maximum current ratings
- Solution : Implement thermal vias, adequate copper pours, and consider derating above 60°C ambient temperature
Pitfall 2: Input Drive Insufficiency
- Problem : Insufficient LED drive current causing unreliable switching
- Solution : Maintain 5-10mA input current for reliable operation, use constant current drive when possible
Pitfall 3: Output Voltage Overshoot
- Problem : Inductive load switching causing voltage spikes
- Solution : Implement snubber circuits or TVS diodes for inductive loads
Pitfall 4: PCB Contamination
- Problem : Flux residue causing leakage currents
- Solution : Thorough cleaning after assembly, conformal coating in humid environments
### Compatibility Issues with Other Components
Microcontroller Interfaces
- Compatible with 3.3V and 5V logic families
- Requires current-limiting resistor for LED drive (typically 330-1000Ω)
- Watch for microcontroller pin current sourcing capability
Power Supply Considerations
- Input side compatible with low-voltage digital circuits
- Output side requires consideration of load characteristics
- Ensure power supply can handle inrush currents for capacitive loads
Load Compatibility
- Resistive Loads : Ideal application, no special considerations
- Inductive Loads : Requires protection against back-EMF
