4N37SD Optoisolator Equivalent & Substitute Parts

Part Overview

The 4N37SD is an optoisolator transistor with base output manufactured by onsemi, rated for 5300Vrms isolation voltage in a 6-SMD surface mount package. This component is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and procurement continuity. The 4N37SD serves as a single-channel optoisolation solution with DC input and transistor output with base access, suitable for applications requiring galvanic isolation in compact form factors.

Substiute Parts

4N37SD

onsemiIn Stock: 11084N37SD Datasheet

Current PartRFQ

4N37SR2M

onsemiIn Stock: 18614N37SR2M Datasheet

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4N37-X009

Vishay Semiconductor Opto DivisionIn Stock: 22444N37-X009 Datasheet

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4N37S

onsemiIn Stock: 32304N37S Datasheet

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4N37S-TA

Lite-On Inc.In Stock: 34104N37S-TA Datasheet

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4N37S-TA1

Lite-On Inc.In Stock: 220534N37S-TA1 Datasheet

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4N37SM

onsemiIn Stock: 127594N37SM Datasheet

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4N37SMT&R

Isocom Components 2004 LTDIn Stock: 8614N37SMT&R Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the 4N37SD is determined by the following critical parameters:

• Isolation Voltage Rating: Minimum 5300Vrms or equivalent
• Output Configuration: Transistor with Base output type
• Number of Channels: Single channel (1)
• Input Type: DC input
• Package Type: 6-SMD, Gull Wing surface mount
• Current Transfer Ratio: Minimum 100% @ 10mA
• Output Voltage Rating: Maximum 30V
• Vce Saturation: Maximum 300mV
• Operating Temperature Range: Must support -55°C ~ 100°C or equivalent

Substitute parts are grouped into two categories based on isolation voltage performance:

Category A - High Isolation (≥5000Vrms): Parts meeting or exceeding the 5300Vrms isolation specification of the 4N37SD, maintaining full electrical equivalence for high-voltage isolation applications.

Category B - Reduced Isolation (<5000Vrms): Parts with lower isolation voltage ratings that may serve as functional alternatives in applications where the full 5300Vrms isolation is not required, provided all other electrical parameters remain compatible.

Parameter Comparison

Engineering Selection Recommendations

Primary Substitute - High Isolation Equivalence:

The 4N37-X009 (Vishay Semiconductor Opto Division) is the closest functional equivalent, maintaining 5000Vrms isolation voltage within 94% of the 4N37SD specification. This part is currently active in production status and ROHS3 compliant. The primary trade-off is increased turn-on/turn-off time (10µs versus 2µs), which may impact applications requiring faster switching response.

Secondary Substitute - onsemi Active Alternative:

The 4N37SM (onsemi) provides 4170Vrms isolation with active product status and ROHS3 compliance. This part maintains identical turn-on/turn-off timing (2µs) and forward voltage characteristics (1.18V) to the 4N37SD. Operating temperature range is reduced to -40°C ~ 100°C, which may limit use in extreme cold environments.

Tertiary Substitute - Tape & Reel Packaging:

The 4N37SR2M (onsemi) offers the same electrical characteristics as 4N37SM with Tape & Reel packaging for automated assembly. This configuration is suitable for high-volume production environments.

Alternative for Reduced Isolation Requirements:

The 4N37S-TA1 (Lite-On Inc.) provides 1500Vrms isolation with the highest inventory availability (21,996 pcs) and active product status. This part is suitable only for applications where isolation voltage requirements are ≤1500Vrms. All other electrical parameters remain compatible with the 4N37SD.

Not Recommended:

The 4N37SMT&R (Isocom Components 2004 LTD) specifies isolation voltage as 7.5Vpk, which is insufficient for high-voltage isolation applications and represents a different product category.

Frequently Asked Questions (FAQ)

Q: Can the 4N37SR2M directly replace the 4N37SD in all applications?

A: The 4N37SR2M is electrically compatible for applications requiring ≤4170Vrms isolation. The primary difference is reduced isolation voltage (4170Vrms versus 5300Vrms). If your application requires the full 5300Vrms isolation specification, the 4N37SR2M is not suitable. Operating temperature range is also reduced to -40°C ~ 100°C.

Q: What is the key difference between 4N37-X009 and 4N37SD?

A: The 4N37-X009 maintains comparable isolation voltage (5000Vrms) but has significantly slower switching characteristics (10µs turn-on/turn-off versus 2µs). This part is manufactured by Vishay Semiconductor Opto Division rather than onsemi. Select this part only if switching speed is not a critical design parameter.

Q: Are the 4N37S-TA and 4N37S-TA1 interchangeable?

A: Yes, both parts are manufactured by Lite-On Inc. with identical electrical specifications (1500Vrms isolation, 100mA output current, 300mV Vce saturation). The 4N37S-TA1 has significantly higher inventory availability. Both are suitable only for applications with ≤1500Vrms isolation requirements.

Q: Does packaging type affect electrical performance?

A: No. Tape & Reel (TR) and Tube packaging contain identical components with different delivery formats. Tape & Reel packaging is optimized for automated assembly lines, while Tube packaging is suitable for manual assembly or lower-volume applications. Electrical performance is identical.

Q: Which substitute part has the best availability?

A: The 4N37S-TA1 has the highest inventory (21,996 pcs). However, this part is limited to 1500Vrms isolation applications. For high-isolation applications (≥5000Vrms), the 4N37-X009 offers the best availability (2,200 pcs) with comparable isolation voltage to the 4N37SD.

Q: Are all substitute parts ROHS3 compliant?

A: All active substitute parts listed (4N37SR2M, 4N37-X009, 4N37S-TA, 4N37S-TA1, 4N37SM, 4N37SMT&R) are ROHS3 compliant. The original 4N37SD and obsolete 4N37S do not specify RoHS status.

Q: What is the impact of reduced operating temperature range on the 4N37SR2M and 4N37SM?

A: Both parts specify -40°C ~ 100°C versus the 4N37SD's -55°C ~ 100°C. These parts are unsuitable for applications requiring operation below -40°C. Verify your application's minimum operating temperature requirement before selection.