4N38SD Optoisolator Equivalent & Substitute Parts

Part Overview

The 4N38SD is an optoisolator transistor with base output manufactured by onsemi, designed for high-voltage isolation applications. This component features 5300Vrms isolation voltage, single-channel transistor output with base connection, and 6-SMD surface mount packaging. The 4N38SD is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and procurement.

Substiute Parts

4N38SD

onsemiIn Stock: 80944N38SD Datasheet

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4N38SR2M

onsemiIn Stock: 124774N38SR2M Datasheet

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4N38SM

onsemiIn Stock: 125964N38SM Datasheet

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4N38SMT&R

Isocom Components 2004 LTDIn Stock: 11024N38SMT&R Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution for the 4N38SD is determined by the following critical parameters:

• Number of Channels: Must be 1 channel
• Output Type: Must be Transistor with Base
• Mounting Type: Must be Surface Mount
• Package / Case: Must be 6-SMD, Gull Wing
• Current Transfer Ratio (Min): Must be 20% @ 10mA or greater
• Voltage - Output (Max): Must be 80V or greater
• Current - Output / Channel: Must be 100mA or greater
• Vce Saturation (Max): Must be 1V or less

The 4N38SD has three identified substitute parts within the onsemi 4N38 series and Isocom Components 4N38 series. These substitutes maintain functional equivalence through matching output characteristics, isolation voltage ratings, and thermal operating ranges, while differing in isolation voltage specifications and packaging formats.

Parameter Comparison

Engineering Selection Recommendations

4N38SR2M (onsemi): This substitute is active and ROHS3 compliant. It maintains the same current transfer ratio, output voltage, and saturation characteristics as the 4N38SD. The isolation voltage is reduced to 4170Vrms, and the operating temperature range is narrowed to -40°C ~ 100°C. Available in Tape & Reel packaging format.

4N38SM (onsemi): This substitute is active and ROHS3 compliant. It provides identical electrical performance to the 4N38SR2M with the same isolation voltage of 4170Vrms and operating temperature range of -40°C ~ 100°C. Available in Bulk packaging format. Moisture sensitivity level is not applicable for this variant.

4N38SMT&R (Isocom Components 2004 LTD): This substitute is active and ROHS3 compliant. It maintains the full operating temperature range of -55°C ~ 100°C matching the 4N38SD. However, the isolation voltage specification differs significantly at 7.5Vpk, and the maximum output current is reduced to 50mA. Available in Tape & Reel packaging format.

Frequently Asked Questions (FAQ)

Q: Can the 4N38SR2M directly replace the 4N38SD?

A: The 4N38SR2M is functionally equivalent for applications where the isolation voltage requirement is 4170Vrms or lower. Both parts share identical current transfer ratio, output voltage, output current, and saturation characteristics. The operating temperature range differs; verify that -40°C ~ 100°C meets your application requirements.

Q: What is the key difference between 4N38SR2M and 4N38SM?

A: Both parts are electrically identical with 4170Vrms isolation voltage and -40°C ~ 100°C operating temperature. The primary difference is packaging format: 4N38SR2M is supplied in Tape & Reel format, while 4N38SM is supplied in Bulk format. Select based on procurement and assembly requirements.

Q: Is the 4N38SMT&R suitable as a substitute for the 4N38SD?

A: The 4N38SMT&R maintains the full -55°C ~ 100°C operating temperature range of the 4N38SD. However, it has a significantly lower isolation voltage specification of 7.5Vpk and reduced maximum output current of 50mA compared to the 4N38SD's 100mA. Use this substitute only if your application isolation voltage requirement is 7.5Vpk or lower and output current does not exceed 50mA.

Q: What packaging options are available for 4N38 optoisolators?

A: The 4N38 series is available in multiple packaging formats: Tape & Reel (TR) for automated assembly, and Bulk for manual assembly or lower-volume applications. All variants maintain the 6-SMD, Gull Wing physical package format.

Q: Are all substitute parts RoHS compliant?

A: The 4N38SR2M, 4N38SM, and 4N38SMT&R are all ROHS3 compliant. The original 4N38SD does not specify RoHS status. All parts are REACH unaffected.