6N139 Optoisolator Equivalent & Substitute Parts

Part Overview

The 6N139 is an optoisolator with Darlington output and base connection, manufactured by Everlight Electronics Co Ltd. It provides 5000Vrms isolation voltage in a single-channel configuration with 8-DIP through-hole packaging. The device is currently in active production status with high inventory availability (81,100 pcs). Substitute parts are identified when equivalent electrical and mechanical parameters are required for circuit redesign, inventory management, or supply chain continuity.

Substiute Parts

6N139

Everlight Electronics Co LtdIn Stock: 812016N139 Datasheet

Current PartRFQ

6N138

Fairchild SemiconductorIn Stock: 121646N138 Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the 6N139 is determined by the following critical parameters:

Mandatory Matching Parameters:

• Voltage - Isolation: 5000Vrms
• Number of Channels: 1
• Output Type: Darlington with Base
• Package / Case: 8-DIP (0.300", 7.62mm)
• Mounting Type: Through Hole
• Input Type: DC

Allowable Parameter Variations:

• Current Transfer Ratio (Min): Substitute must meet or exceed 300% @ 1.6mA
• Current - Output / Channel: Substitute must support minimum 60mA
• Voltage - Output (Max): Substitute must support minimum 7V
• Operating Temperature: Substitute range may differ but must cover operational requirements
• Turn On / Turn Off Time: Timing specifications may vary within application tolerance

The 6N138 manufactured by Fairchild Semiconductor qualifies as a substitute based on matching isolation voltage, channel count, output configuration, and package type. Differences in current transfer ratio, output voltage rating, and switching speed are within acceptable variation for equivalent circuit functionality.

Parameter Comparison

Engineering Selection Recommendations

Primary Selection: 6N139 (Everlight Electronics)

The 6N139 is the recommended choice for new designs and production applications. It maintains active product status with robust inventory (81,100 pcs available), ensuring supply chain reliability. The device is ROHS3 compliant, meeting current environmental and regulatory requirements. Superior current transfer ratio (500% vs. 300%) and faster switching times (200ns turn-on vs. 1.35µs) provide performance margin for demanding applications. Maximum output voltage rating of 18V accommodates higher voltage circuit topologies compared to the 6N138.

Substitute Selection: 6N138 (Fairchild Semiconductor)

The 6N138 is suitable only for legacy system maintenance or when existing inventory must be utilized. This part is obsolete and non-compliant with ROHS3 standards. Substitution is valid only when circuit design tolerates lower current transfer ratio (300% minimum), reduced output voltage rating (7V maximum), and slower switching response (1.35µs turn-on, 7.6µs turn-off). The wider operating temperature range (-55°C to 100°C) may benefit applications requiring extended thermal operation. Pin-for-pin compatibility in 8-DIP package enables direct socket replacement without PCB modification.

Substitution Constraints:

• Output voltage circuit requirements must not exceed 7V when using 6N138
• Switching speed-critical applications should verify timing compatibility
• New designs must not specify 6N138 due to obsolete status and non-compliance
• Inventory depletion of 6N139 is unlikely given current stock levels

Frequently Asked Questions (FAQ)

Q: Can the 6N138 be used as a direct replacement for the 6N139 in existing circuits?

A: Pin-for-pin replacement is mechanically possible due to identical 8-DIP packaging. However, electrical compatibility depends on circuit design. The 6N138 has lower current transfer ratio (300% vs. 500%), slower switching times, and reduced maximum output voltage (7V vs. 18V). Verify that your circuit tolerates these parameter differences before substitution.

Q: What is the primary reason to substitute the 6N139 with the 6N138?

A: Substitution is justified only for legacy system maintenance when 6N138 inventory exists or when supply of 6N139 is temporarily unavailable. For new designs, the 6N139 is the only acceptable choice due to active production status and ROHS3 compliance.

Q: Are there any package or pinout differences between these parts?

A: No. Both parts use identical 8-DIP (0.300", 7.62mm) through-hole packaging with matching pin assignments. PCB layout and footprints are fully compatible.

Q: What is the impact of the 500% vs. 300% current transfer ratio difference?

A: The 6N139 provides higher optical coupling efficiency, requiring less input current to achieve full output saturation. The 6N138 requires higher input drive current for equivalent output performance. Circuit input stage design must accommodate this difference.

Q: Why is the 6N138 listed as obsolete?

A: The 6N138 is end-of-life from Fairchild Semiconductor. No new production is scheduled. Existing inventory is limited (12,100 pcs) and will eventually deplete. The 6N139 from Everlight Electronics is the active replacement in the market.

Q: Does RoHS compliance affect substitution decisions?

A: Yes. The 6N139 is ROHS3 compliant, meeting current environmental regulations for commercial and industrial applications. The 6N138 is non-compliant. Regulatory requirements, customer specifications, or industry standards may mandate use of compliant components, making the 6N139 mandatory regardless of technical equivalence.

Q: What switching speed considerations apply to substitution?

A: The 6N139 has significantly faster switching (200ns turn-on, 1.7µs turn-off) compared to the 6N138 (1.35µs turn-on, 7.6µs turn-off). Applications with high-frequency switching or tight timing requirements must verify that 6N138 switching delays do not violate system performance specifications.

Q: Can the 6N138 operate at the full 18V output voltage of the 6N139?

A: No. The 6N138 is rated for maximum 7V output. Circuits requiring output voltages above 7V must use the 6N139. Exceeding the 6N138 voltage rating will cause device failure.