Frequently Asked Questions (FAQ)
The following answers address common questions from researchers, engineers, and students in optoelectronics and related fields regarding optoelectronic device selection and usage. For further technical support, please contact us.
1. What are the main types of optocouplers and how to select them for research applications?
Optocouplers are classified by output type: transistor output, Darlington output, Schmitt trigger output, and photo-TRIAC output. Key selection criteria:
- Isolation voltage: 2500V minimum, 5000V for high-voltage experiments
- Current Transfer Ratio (CTR): 50%-200% for signal, higher for power drive
- Response speed: < 4us for high-speed signal transmission
- Package: DIP for prototyping, SMD for compact designs
2. What is the difference between PhotoMOS relays and electromagnetic relays?
| Feature | PhotoMOS Relay | EMR |
|---|---|---|
| Contact type | Contactless (solid state) | Mechanical |
| Lifetime | Practically unlimited (>10^8) | Limited (10^5-10^6) |
| On-resistance | Several ohms | Very low (<1 ohm) |
| Response time | Fast (ms) | Slower (5-20ms) |
| Spark/EMI | None | Yes |
| Best for | Precision measurement, ATE | High power, low cost |
3. How to understand isolation voltage and select for research experiments?
- Standard signal isolation: 2500Vrms sufficient
- High-voltage experiments (power electronics): 5000Vrms recommended
- Medical devices: IEC 60601-1 compliance, 4000Vrms+
- Working voltage is typically 1/3 to 1/2 of isolation voltage
4. How does PhotoMOS relay on-resistance affect precision measurements?
- Voltage divider effect: Ron causes voltage division in high-impedance circuits
- Thermal noise: Ron introduces Johnson noise affecting weak signal measurement
- Selection tip: Choose Ron < 5 ohm for precision applications
- Compensation: Use 4-wire (Kelvin) measurement to eliminate Ron effect
5. Precautions for using solid state relays in research labs?
- Heat sinking: Required for high-current applications
- Overcurrent protection: Use fast-blow fuses
- Overvoltage protection: RC snubber or varistor for inductive loads
- Leakage current: May prevent complete shutoff with high-impedance loads
- Load matching: AC SSRs cannot be used for DC loads
6. What is the operating temperature range of CONQUER OC products?
Standard products: -40C to +85C operating, -55C to +125C storage. Industrial-grade products up to +110C. Custom solutions available for extreme environments.
7. How to request product samples and what is the delivery time?
- Submit sample request via our contact page with institution, research field, and required models
- Standard samples shipped within 3-5 business days
- Bulk orders: 2-4 weeks depending on model and quantity
- Free samples and technical support available for research users
8. How does optocoupler response time affect high-speed signal transmission?
- Standard optocouplers (Tr/Tf ~4us): kHz signals, serial communication
- High-speed optocouplers (<1us): MHz signals, SPI communication
- Ultra-high-speed (<50ns): 10MHz+ signals, high-speed data acquisition
- Formula: fmax = 1/(3 x (Tr+Tf))
For detailed technical documentation or selection assistance, please visit our technical articles or contact us.
