CNY21 Optocoupler Technical Summary

Overview

The CNY21 is a high-performance optocoupler designed to provide electrical isolation between two circuits while allowing signal transmission through an optical link. It consists of a gallium arsenide (GaAs) infrared emitting diode optically coupled to a phototransistor. This configuration ensures reliable signal transfer while maintaining high isolation between input and output.

This component is particularly suitable for applications requiring high voltage isolation and noise immunity. The CNY21 series offers excellent performance in industrial environments where electrical noise and potential differences between system components could cause issues.

Features

• UL recognized (File No. E 76414) for safety compliance
• High isolation test voltage: 10 kV DC
• Excellent creeping current resistance of isolation material
• Compact and robust design for reliable operation
• Infrared LED with GaAs technology for efficient light emission
• Phototransistor output for easy interface with digital circuits
• Wide operating temperature range suitable for industrial applications
• High common-mode rejection for noise immunity
• Long-term reliability with stable performance characteristics

Applications

The CNY21 optocoupler finds use in numerous applications where electrical isolation is required:

• Industrial control systems
• Power supply feedback circuits
• Medical equipment isolation
• Telecommunication systems
• Microprocessor system interfaces
• Ground loop elimination
• Noise suppression in measurement systems
• Motor control circuits
• Automotive electronics
• Safety-critical isolation barriers

Electrical Characteristics

Input Characteristics (Infrared LED)

• Forward voltage (V_F): 1.2V typical at 20mA
• Reverse voltage (V_R): 5V maximum
• Forward current (I_F): 60mA maximum
• Power dissipation: 100mW maximum
• Wavelength: 950nm typical

Output Characteristics (Phototransistor)

• Collector-emitter voltage (V_CEO): 30V minimum
• Emitter-collector voltage (V_ECO): 5V maximum
• Collector current (I_C): 50mA maximum
• Dark current (I_D): 50nA maximum at V_CE=10V
• Collector-emitter saturation voltage: 0.4V maximum at I_C=2mA

Transfer Characteristics

• Current transfer ratio (CTR): 20% minimum at I_F=10mA, V_CE=5V
• Isolation resistance: 10¹²Ω minimum
• Isolation capacitance: 0.5pF typical
• Response time (t_r): 3μs typical
• Fall time (t_f): 2μs typical

Package Information

The CNY21 is available in a standard 6-pin DIP (Dual In-line Package) configuration:

• Package type: Through-hole DIP
• Pin count: 6 (4 active pins, 2 NC)
• Pin spacing: 2.54mm (standard DIP pitch)
• Row spacing: 7.62mm
• Package material: Black thermoplastic
• Flammability rating: UL94 V-0
• Lead material: Tin-plated copper alloy
• Operating temperature range: -55°C to +100°C
• Storage temperature range: -55°C to +125°C

Pin Configuration

• Pin 1: Anode of infrared LED
• Pin 2: Cathode of infrared LED
• Pin 3: No connection
• Pin 4: Emitter of phototransistor
• Pin 5: Collector of phototransistor
• Pin 6: No connection

Reliability and Safety

The CNY21 optocoupler is designed to meet stringent reliability and safety requirements:

• UL recognized component (File E 76414)
• High voltage isolation tested to 10kV DC
• Creepage and clearance distances optimized for safety
• Material selection for long-term stability
• Manufactured under strict quality control procedures
• ESD protection built into the device structure

Design Considerations

When implementing the CNY21 in circuit designs, consider the following:

LED Drive Circuit

The infrared LED should be driven with appropriate current limiting to ensure proper operation and longevity. A series resistor is typically used to limit current to the recommended operating range (10-50mA).

Output Circuit Design

The phototransistor output can be configured in common-emitter or common-collector configurations depending on application requirements. A pull-up resistor is typically required for proper operation in switching applications.

PCB Layout

Maintain proper creepage distances between input and output circuits to preserve the high voltage isolation characteristics. Keep high-speed or noisy traces away from the optocoupler to prevent interference.

Environmental Compliance

The CNY21 complies with various environmental standards:

• RoHS compliant (lead-free)
• REACH compliant
• Halogen-free material composition