TIL921

TIL921 Optocoupler Technical Summary

Overview

The TIL921 is a dual-channel optocoupler designed for AC-input applications, featuring two gallium-arsenide (GaAs) light-emitting diodes (LEDs) in a reverse-parallel configuration and silicon NPN phototransistors for signal isolation. This component provides reliable electrical isolation between input and output circuits while enabling signal transmission across an insulating barrier. Housed in an 8-pin package, the TIL921 is part of a family that includes single-channel (TIL920) and quad-channel (TIL922) variants, offering design flexibility for various isolation requirements.

Key Features

• Dual-Channel Configuration: Two independent optocoupler channels in a single 8-pin package
• AC Input Capability: Reverse-parallel GaAs LEDs enable alternating current input operation
• High Isolation Voltage: Provides electrical isolation between input and output circuits
• Current Transfer Ratio (CTR): Standard version tested for 20% minimum CTR with options for 50% and 100% minimum CTR available
• Fast Response Time: Suitable for moderate speed signal transmission applications
• Wide Operating Temperature Range: Designed for reliable performance across industrial temperature ranges
• Compact Package: Space-efficient 8-pin DIP (Dual In-line Package) configuration

Applications

The TIL921 optocoupler is designed for a wide range of applications requiring electrical isolation and signal transmission:

• Industrial Control Systems: PLC I/O isolation, motor control circuits
• Power Supply Regulation: Feedback loop isolation in switch-mode power supplies
• Telecommunications: Signal isolation in communication interfaces
• Medical Equipment: Patient-isolated circuits in medical devices
• AC Line Monitoring: Zero-crossing detection and voltage sensing
• Digital Logic Isolation: Interface between different voltage domains
• Noise Suppression: Breaking ground loops in sensitive measurement circuits

Electrical Characteristics

The following table summarizes key electrical parameters for the TIL921 optocoupler:

Input Characteristics (LED Side)

• Forward Voltage (V_F): 1.15V typical at 10mA
• Reverse Voltage (V_R): 3V maximum
• Continuous Forward Current (I_F): 60mA maximum
• Peak Forward Current (I_FP): 1A maximum (1μs pulse)
• Power Dissipation: 100mW per channel maximum

Output Characteristics (Phototransistor Side)

• Collector-Emitter Voltage (V_CEO): 30V minimum
• Emitter-Collector Voltage (V_ECO): 7V maximum
• Collector Current (I_C): 50mA maximum
• Collector Power Dissipation: 150mW maximum
• Dark Current (I_D): 50nA maximum at V_CE=10V

Transfer Characteristics

• Current Transfer Ratio (CTR): 20% minimum (standard version)
• Isolation Voltage: 2500V_RMS minimum input to output
• Response Time (t_r): 3μs typical (10% to 90% of final value)
• Fall Time (t_f): 5μs typical (90% to 10% of final value)

Absolute Maximum Ratings

• Storage Temperature Range: -55°C to +125°C
• Operating Temperature Range: -40°C to +85°C
• Soldering Temperature: 260°C for 10 seconds maximum

Package Information

The TIL921 is available in an 8-pin dual in-line package (DIP) with the following mechanical characteristics:

Package Dimensions

• Package Type: 8-pin DIP (Dual In-line Package)
• Body Length: 9.65mm nominal
• Body Width: 6.35mm nominal
• Body Height: 3.81mm nominal
• Lead Pitch: 2.54mm (0.1 inch) standard
• Lead Length: 3.3mm minimum below seating plane

Pin Configuration

• Pin 1: Anode of LED 1
• Pin 2: Cathode of LED 1
• Pin 3: Anode of LED 2
• Pin 4: Cathode of LED 2
• Pin 5: Emitter of Phototransistor 2
• Pin 6: Collector of Phototransistor 2
• Pin 7: Emitter of Phototransistor 1
• Pin 8: Collector of Phototransistor 1

Reliability and Environmental Characteristics

• Isolation Resistance: 10¹¹Ω minimum at 500V DC
• Dielectric Strength: 2500V_RMS for 1 minute between input and output
• Moisture Sensitivity Level (MSL): MSL 1 (Unlimited floor life at ≤30°C/85% RH)
• Flammability Rating: UL94 V-0 compliant

Design Considerations

When implementing the TIL921 in circuit designs, consider the following:

• LED Current Limiting: Always use appropriate series resistors to limit forward current
• Reverse Voltage Protection: The built-in reverse-parallel LED configuration handles AC inputs
• Phototransistor Loading: Use appropriate pull-up resistors for digital applications
• PCB Layout: Maintain proper creepage and clearance distances for high voltage isolation
• Thermal Considerations: Observe maximum power dissipation limits in high ambient temperatures

Ordering Information

The TIL921 is available in several variants based on current transfer ratio specifications:

• TIL921: Standard version with 20% minimum CTR
• TIL921-50: Selected version with 50% minimum CTR
• TIL921-100: Selected version with 100% minimum CTR

Consult manufacturer documentation for current packaging options and tape/reel availability.