4N38 Optoisolator Transistor with Base - Equivalent & Substitute Parts

Part Overview

The 4N38 is a single-channel optoisolator with transistor output and base connection, rated for 5300Vrms isolation voltage. This component is classified as obsolete by the original manufacturer (onsemi). Due to its discontinued status, equivalent and substitute parts from active manufacturers are necessary for new designs and ongoing production requirements. Substitute parts maintain functional compatibility through matching electrical characteristics and identical 6-DIP package specifications.

Substiute Parts

4N38

onsemiIn Stock: 73714N38 Datasheet

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4N38M

onsemiIn Stock: 30414N38M Datasheet

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4N25-000E

Broadcom LimitedIn Stock: 30614N25-000E Datasheet

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4N38

onsemiIn Stock: 73714N38 Datasheet

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4N38

onsemiIn Stock: 73714N38 Datasheet

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4N38

onsemiIn Stock: 73714N38 Datasheet

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4N38-V

Everlight Electronics Co LtdIn Stock: 9544N38-V Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the 4N38 is determined by the following critical parameters:

• Package / Case: Must be 6-DIP (0.300", 7.62mm) for mechanical compatibility
• Output Type: Must be Transistor with Base
• Number of Channels: Must be 1
• Input Type: Must be DC
• Voltage - Isolation: Minimum 5300Vrms or lower (downgrade acceptable for lower isolation requirements)
• Current Transfer Ratio (Min): Must be 20% @ 10mA or higher
• Voltage - Output (Max): Must be 80V or higher
• Current - Output / Channel: Must be 100mA or higher
• Mounting Type: Must be Through Hole

Substitute parts are grouped based on isolation voltage rating and product status. Parts with equal or higher isolation voltage and active product status are preferred for new designs.

Parameter Comparison

Engineering Selection Recommendations

Primary Substitute: 4N38M (onsemi)

The 4N38M is the direct active-status equivalent from the original manufacturer. It maintains the same electrical performance characteristics (20% CTR minimum, 5µs switching times, 80V output rating, 100mA output current) and identical 6-DIP package. The isolation voltage is reduced to 4170Vrms, which is acceptable for applications not requiring the full 5300Vrms specification. This part carries ROHS3 compliance and is currently in active production status.

Secondary Substitute: 4N38-V (Everlight Electronics)

The 4N38-V provides near-equivalent isolation voltage (5000Vrms) with active product status and ROHS3 compliance. It maintains the 20% CTR minimum, 80V output rating, and 6-DIP package. Operating temperature range extends to 110°C. Switching times are slightly slower (10µs, 9µs) compared to the original 4N38. This part is suitable for applications requiring high isolation voltage with extended temperature operation.

Tertiary Substitute: 4N25-000E (Broadcom Limited)

The 4N25-000E is a lower-isolation-voltage alternative (2500Vrms) with active product status and ROHS3 compliance. It maintains the 20% CTR minimum, 100mA output current, and 6-DIP package. The output voltage rating is reduced to 30V maximum, and Vce saturation is improved to 500mV. This part is suitable only for applications with isolation voltage requirements of 2500Vrms or lower.

Frequently Asked Questions (FAQ)

Q: Can the 4N38M directly replace the 4N38 in all applications?

A: The 4N38M is mechanically and electrically compatible for most applications. The primary difference is reduced isolation voltage (4170Vrms vs. 5300Vrms). If your circuit requires the full 5300Vrms isolation specification, the 4N38M is not suitable. For applications with lower isolation requirements, the 4N38M is a direct replacement.

Q: What is the key difference between the 4N38-V and the original 4N38?

A: The 4N38-V maintains comparable isolation voltage (5000Vrms vs. 5300Vrms) and identical output specifications (80V, 100mA). The switching times are slower (10µs/9µs vs. 5µs/5µs). The 4N38-V is suitable for applications where switching speed is not critical and extended temperature operation (-55°C to 110°C) is required.

Q: Is the 4N25-000E a suitable replacement for the 4N38?

A: The 4N25-000E is suitable only if your application requires isolation voltage of 2500Vrms or lower. It is not suitable for applications requiring the full 5300Vrms isolation of the original 4N38. The reduced output voltage rating (30V vs. 80V) must also be verified against circuit requirements.

Q: Are all substitute parts available in the same packaging?

A: Yes. All substitute parts listed (4N38M, 4N25-000E, 4N38-V) are supplied in 6-DIP (0.300", 7.62mm) packages, identical to the original 4N38. Through-hole mounting compatibility is maintained across all parts.

Q: Which substitute part has the best compliance status?

A: All active substitute parts (4N38M, 4N25-000E, 4N38-V) carry ROHS3 compliance. The 4N38M and 4N25-000E both carry REACH Unaffected status. For new designs, any of these three parts meet current regulatory compliance requirements.

Q: What is the minimum current transfer ratio for all parts?

A: All listed parts, including the original 4N38 and all substitutes, maintain a minimum current transfer ratio of 20% @ 10mA. This parameter is consistent across the entire product family.