6N135 High-Speed Optocoupler

Overview

The 6N135 is a high-speed optocoupler designed for applications requiring robust electrical isolation between input and output circuits. This component is part of a family of optocouplers (including the 6N136 and HCPL4502) that combine a light-emitting diode (LED) with an integrated photon detector. The detector consists of a photodiode and an open-collector output transistor, enabling superior performance in both analog and digital interface applications.

Key to its design is the separate connection for photodiode bias and transistor-collector output, which significantly reduces base-to-collector capacitance. This architectural improvement allows the 6N135 to achieve speeds up to 100 times faster than conventional phototransistor-based optocouplers.

Features

• High-Speed Performance: Optimized for applications requiring fast signal transmission across isolation barriers.
• High Common-Mode Transient Immunity: Excellent noise rejection in electrically noisy environments.
• Wide Operating Temperature Range: Suitable for industrial applications with temperatures from -40°C to +85°C.
• Low Input Current Requirement: Typically 10mA forward current for the LED.
• Open-Collector Output: Provides flexibility in interfacing with various logic families.
• High Isolation Voltage: Typically 2500V_rms for 1 minute, ensuring robust electrical separation.
• Separate Photodiode Bias: Reduces transistor capacitance for improved speed.

Applications

The 6N135 is designed for use in applications requiring high-voltage isolation and fast signal transmission:

• Industrial Control Systems: Isolated digital and analog signal transmission in PLCs and motor drives.
• Medical Equipment: Patient-isolated monitoring and control circuits.
• Telecommunications: Line receivers and interface isolation.
• Power Supply Control: Feedback loop isolation in switch-mode power supplies.
• Test and Measurement Equipment: Isolated signal acquisition and processing.
• Computer Peripherals: Isolation in serial communications and interface circuits.

Electrical Characteristics

Absolute Maximum Ratings

• Input Forward Current: 60mA (continuous)
• Reverse Input Voltage: 5V
• Output Collector-Emitter Voltage: 30V
• Output Emitter-Collector Voltage: 5V
• Total Power Dissipation: 150mW
• Isolation Voltage: 2500V_rms (1 minute)
• Operating Temperature Range: -40°C to +85°C
• Storage Temperature Range: -55°C to +125°C

Recommended Operating Conditions

• Input Forward Current: 10mA (typical)
• Supply Voltage (V_CC): 4.5V to 20V
• Photodiode Bias Voltage: 4.5V to 5.5V
• Operating Frequency: Up to 1MHz (depending on configuration)

Performance Characteristics (T_A = 25°C unless noted)

• Current Transfer Ratio (CTR): 15% minimum at I_F = 10mA
• Propagation Delay (t_PLH): 0.8μs typical
• Propagation Delay (t_PHL): 0.8μs typical
• Rise Time (t_r): 0.3μs typical
• Fall Time (t_f): 0.3μs typical
• Common-Mode Transient Immunity: 10kV/μs minimum

Package Information

The 6N135 is available in a standard 8-pin DIP (Dual In-line Package) with the following mechanical characteristics:

• Package Type: 8-pin DIP (Dual In-line Package)
• Package Material: Molded plastic
• Lead Finish: Matte tin (RoHS compliant)
• Pin Spacing: 2.54mm (0.1 inch) between pins
• Row Spacing: 7.62mm (0.3 inch) between rows
• Package Dimensions: 9.65mm x 6.35mm x 3.3mm (L x W x H)
• Weight: Approximately 0.5 grams

Pin Configuration

• Pin 1: Anode (LED positive)
• Pin 2: Cathode (LED negative)
• Pin 3: No Connection
• Pin 4: Photodiode Anode
• Pin 5: Photodiode Cathode
• Pin 6: Transistor Collector
• Pin 7: Transistor Emitter
• Pin 8: No Connection

Design Considerations

Input Circuit Design

The LED should be driven with a current-limiting resistor to maintain the recommended 10mA forward current. A typical circuit would include a series resistor calculated as:

R_limit = (V_supply - V_F) / I_F

Where V_F is the forward voltage of the LED (typically 1.2V at 10mA).

Output Circuit Design

The open-collector output requires a pull-up resistor for proper operation. The value depends on the desired speed and power consumption:

• For higher speed: Use lower resistance (1kΩ to 4.7kΩ)
• For lower power: Use higher resistance (10kΩ to 47kΩ)

The photodiode bias (pins 4 and 5) should be connected to a stable voltage source between 4.5V and 5.5V for optimal performance.

Reliability and Safety

The 6N135 is designed for reliable operation in demanding environments:

• Isolation Voltage: Tested to 2500V_rms for 1 minute
• Creepage Distance: Minimum 7.5mm between input and output
• Clearance Distance: Minimum 7.5mm between input and output
• Safety Approvals: Typically UL1577 recognized (file E90700)

Environmental Compliance

The 6N135 is compliant with the following environmental standards:

• RoHS compliant (Restriction of Hazardous Substances)
• Halogen-free