TIL918

TIL918 Dual-Channel Optocoupler Technical Summary

Overview

The TIL918 is a dual-channel optocoupler consisting of a gallium-arsenide (GaAs) light-emitting diode (LED) optically coupled to a silicon n-p-n Darlington phototransistor in each channel. Housed in an 8-pin package, it provides electrical isolation between input and output circuits while allowing signal transmission through light. This device is part of a family that includes single-channel (TIL917) and quad-channel (TIL919) variants, with selectable current-transfer ratio (CTR) grades for different performance requirements.

Key advantages include high voltage isolation, noise immunity, and the ability to interface between circuits of different potential levels. The Darlington phototransistor configuration provides higher current gain compared to standard phototransistor optocouplers.

Features

• Dual-channel optocoupler in 8-pin package
• GaAs LED coupled with n-p-n Darlington phototransistor
• Current-transfer ratio (CTR) options:
  • Standard grade: 20% minimum
  • Grade A: 50% minimum CTR
  • Grade B: 100% minimum CTR
  • Grade C: 200% minimum CTR
• High isolation voltage (typically 2500V_RMS)
• Wide operating temperature range
• Compact DIP package
• Reliable performance in noisy environments
• Compatible with standard PCB assembly processes

Applications

• Industrial control systems
• Power supply feedback circuits
• Microprocessor system interfaces
• Ground loop elimination
• Noise immunity in data acquisition systems
• Medical equipment isolation
• Telecommunications equipment
• Motor control circuits
• Solid-state relay replacements
• Analog signal isolation

Electrical Characteristics

(All values typical at 25°C unless otherwise specified)

Input Characteristics (LED Side)

• Forward voltage (I_F = 10mA): 1.15V to 1.5V
• Reverse voltage: 3V maximum
• Forward current (continuous): 60mA maximum
• Peak forward current (1μs pulse): 1A maximum
• Power dissipation: 100mW maximum

Output Characteristics (Phototransistor Side)

• Collector-emitter voltage: 30V minimum
• Emitter-collector voltage: 7V maximum
• Collector current (continuous): 150mA maximum
• Power dissipation: 250mW maximum
• Dark current (V_CE = 10V): 100nA maximum

Transfer Characteristics

• Current transfer ratio (CTR):
  • Standard: 20% minimum
  • Grade A: 50% minimum
  • Grade B: 100% minimum
  • Grade C: 200% minimum
• Response time (turn-on): 15μs typical
• Response time (turn-off): 100μs typical
• Isolation resistance: 10¹¹Ω minimum
• Isolation capacitance: 1pF typical

Absolute Maximum Ratings

• Storage temperature range: -55°C to +125°C
• Operating temperature range: -40°C to +85°C
• Soldering temperature (10 sec): 260°C maximum
• Isolation voltage (1 minute): 2500V_RMS

Package Information

The TIL918 is available in an 8-pin dual in-line package (DIP) with the following mechanical specifications:

Physical Dimensions

• Package type: 8-pin DIP
• Overall length: 21.1mm (0.831 inches) maximum
• Body width: 10.2mm (0.400 inches) maximum
• Body height: 4.80mm (0.189 inches) maximum
• Pin spacing: 2.54mm (0.100 inches) between pins
• Row spacing: 7.62mm (0.300 inches) typical
• Pin diameter: 0.51mm (0.020 inches) minimum
• Pin length: 5.08mm (0.200 inches) maximum

Package Outline

The package follows standard DIP dimensions with the following key features:

• All linear dimensions in millimeters (inches in parentheses)
• Pin centerline tolerance: ±0.25mm (±0.010 inches)
• Seating plane clearly defined for PCB mounting
• Lead-free and RoHS compliant versions available

Reliability and Compliance

• Manufactured under Texas Instruments' quality standards
• Production tested to meet all published specifications
• Standard warranty applies to all devices
• ESD protection: 2kV (Human Body Model)
• Flammability rating: UL94 V-0

Design Considerations

When implementing the TIL918 in circuit designs, consider the following:

• Proper current limiting for the input LED is essential for reliability
• The Darlington configuration provides higher gain but slower response than single phototransistors
• CTR degrades with time - design with appropriate margin
• Thermal considerations are important for high-current applications
• For analog applications, linearity should be verified across the operating range
• PCB layout should maintain proper creepage and clearance distances

Ordering Information

The TIL918 is available in several variants based on CTR performance:

• TIL918: Standard version with 20% minimum CTR
• TIL918A: 50% minimum CTR
• TIL918B: 100% minimum CTR
• TIL918C: 200% minimum CTR

Contact Texas Instruments or authorized distributors for current packaging options and lead times.