6N138 Optoisolator Equivalent & Substitute Parts

Part Overview

The 6N138 is a Darlington optoisolator with base output manufactured by Everlight Electronics Co Ltd, designed for high-voltage isolation applications requiring 5000Vrms isolation rating. This component integrates an LED input stage with a Darlington transistor output stage, providing galvanic isolation in single-channel configurations. The part is currently in Active product status with 12100 pieces available in inventory.

Substitute parts are identified when equivalent electrical and mechanical parameters are maintained across isolation voltage, current transfer ratio, output configuration, package type, and operating temperature range. The identification of alternative sources becomes necessary when primary supplier availability changes, when design requirements mandate specific compliance certifications, or when inventory constraints necessitate qualified alternatives.

Substiute Parts

6N138

Everlight Electronics Co LtdIn Stock: 121606N138 Datasheet

Current PartRFQ

6N138

Fairchild SemiconductorIn Stock: 121646N138 Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the 6N138 is determined by strict equivalence across the following critical parameters:

Electrical Equivalence Criteria:

• Isolation voltage rating of 5000Vrms minimum
• Current transfer ratio minimum of 300% at 1.6mA input current
• Darlington with base output configuration
• Maximum output current of 60mA per channel
• Single-channel configuration
• DC input type

Mechanical Equivalence Criteria:

• 8-DIP package with 0.300" (7.62mm) pitch
• Through-hole mounting technology
• Tube packaging format

Environmental Criteria:

• Operating temperature range must encompass or match the specified range

Parts meeting all electrical, mechanical, and environmental criteria are classified as direct substitutes. Variations in secondary parameters such as turn-on/turn-off time, forward voltage, or maximum forward current do not disqualify substitution when primary isolation and output characteristics remain equivalent.

Parameter Comparison

Engineering Selection Recommendations

Primary Selection: 6N138 (Everlight Electronics Co Ltd)

The Everlight 6N138 is the recommended primary choice for new designs and production applications. This part maintains Active product status, ensuring long-term availability and supply chain stability. The component carries ROHS3 compliance certification, meeting current environmental and regulatory requirements for commercial and industrial applications. The operating temperature range of -40°C to 85°C covers standard industrial and consumer electronics environments.

Alternative Selection: 6N138 (Fairchild Semiconductor)

The Fairchild Semiconductor 6N138 maintains electrical and mechanical equivalence with identical isolation voltage, current transfer ratio, output configuration, and package specifications. However, this part carries Obsolete product status, indicating discontinued manufacturing and limited future availability. Additionally, this variant is RoHS non-compliant, which may restrict its use in applications subject to environmental regulations or customer specifications requiring RoHS certification.

The Fairchild variant may be considered only in legacy system maintenance scenarios where existing inventory exists and regulatory compliance is not a design constraint. For new designs, the Everlight part is the appropriate selection.

Frequently Asked Questions (FAQ)

Q: Can the Fairchild 6N138 be used as a direct replacement for the Everlight 6N138?

A: Electrical and mechanical substitution is possible. Both parts share identical isolation voltage (5000Vrms), current transfer ratio (300% minimum), Darlington output configuration, and 8-DIP package specifications. However, the Fairchild part is Obsolete and RoHS non-compliant, making it unsuitable for new designs or applications requiring environmental compliance.

Q: What are the critical parameters that determine substitution eligibility?

A: Substitution requires equivalence in isolation voltage rating, current transfer ratio minimum specification, output stage configuration (Darlington with base), maximum output current, package type (8-DIP through-hole), and operating temperature range. Secondary parameters such as switching speed or forward voltage variation do not prevent substitution when primary specifications match.

Q: Are there differences in switching performance between the two variants?

A: Minor differences exist in turn-on/turn-off timing. The Everlight variant specifies 1.4µs turn-on and 8µs turn-off, while the Fairchild variant specifies 1.35µs turn-on and 7.6µs turn-off. These differences are within typical application tolerances for optoisolator circuits and do not affect functional substitution.

Q: What is the significance of the operating temperature range difference?

A: The Everlight part operates from -40°C to 85°C, while the Fairchild part operates from -55°C to 100°C. The Fairchild range is wider, but the Everlight range covers standard industrial and commercial temperature requirements. Selection should be based on specific application temperature requirements rather than range width alone.

Q: Does RoHS compliance affect electrical performance?

A: RoHS compliance relates to material composition and environmental regulations, not electrical performance. Both parts function identically in circuit operation. RoHS compliance becomes a selection criterion only when regulatory requirements or customer specifications mandate it.

Q: Can these parts be used interchangeably in existing PCB designs?

A: Yes, both parts use identical 8-DIP through-hole packaging with 0.300" (7.62mm) pitch, allowing direct PCB footprint compatibility. No layout or mechanical modifications are required for substitution.