4N29S Optoisolator Equivalent & Substitute Parts

Part Overview

The 4N29S is a single-channel optoisolator with Darlington output and base connection, manufactured by onsemi. It provides 5300Vrms isolation voltage in a 6-SMD surface mount package. The part is currently obsolete, making equivalent and substitute parts necessary for ongoing design support and production continuity. Substitute parts must maintain compatibility across isolation voltage, output configuration, channel count, and package type while meeting the electrical performance requirements of the original design.

Substiute Parts

4N29S

onsemiIn Stock: 11154N29S Datasheet

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4N29SM

onsemiIn Stock: 51484N29SM Datasheet

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4N29SM

onsemiIn Stock: 51484N29SM Datasheet

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4N29SMT&R

Isocom Components 2004 LTDIn Stock: 19054N29SMT&R Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution of the 4N29S is constrained by the following critical parameters:

• Isolation Voltage: The 4N29S provides 5300Vrms isolation. Substitute parts must maintain this isolation level or exceed it to preserve circuit safety margins.
• Output Configuration: Darlington output with base connection is required for direct pin compatibility.
• Channel Count: Single-channel configuration must be maintained.
• Package Type: 6-SMD, Gull Wing surface mount package is mandatory for PCB layout compatibility.
• Electrical Performance: Current transfer ratio, output voltage rating, output current capability, and switching times must be equivalent or superior.

The 4N29SM from onsemi shares the same base product number (4N29) and package configuration but operates at a reduced isolation voltage of 4170Vrms. The 4N29SMT&R from Isocom Components 2004 LTD is a functionally equivalent alternative available in Tape & Reel packaging, suitable for high-volume production environments.

Parameter Comparison

Engineering Selection Recommendations

4N29SM (onsemi): This part is the primary substitute for the 4N29S. Both parts share the same base product number and are manufactured by onsemi. The 4N29SM is currently in active production status with ROHS3 compliance certification. The isolation voltage is reduced to 4170Vrms compared to the 5300Vrms of the 4N29S; circuit designs must confirm that this lower isolation rating is acceptable for the intended application. All other electrical parameters—output type, current transfer ratio, switching times, and output current capability—are identical. The operating temperature range is narrower (-40°C to 100°C versus -55°C to 100°C), which may affect suitability for extended low-temperature applications. Tube packaging is standard for this variant.

4N29SMT&R (Isocom Components 2004 LTD): This part provides an alternative source for high-volume production requirements. It is available in Tape & Reel packaging, which is optimized for automated assembly processes. The part is in active production status with ROHS3 compliance. Detailed electrical specifications beyond the 6-pin Darlington output configuration are not provided in the available data; verification of isolation voltage, output current rating, and switching characteristics against design requirements is necessary before selection.

Frequently Asked Questions (FAQ)

Q: Can the 4N29SM directly replace the 4N29S in existing designs?

A: The 4N29SM is pin-compatible and functionally equivalent in terms of output configuration, current transfer ratio, and switching performance. However, the isolation voltage is reduced from 5300Vrms to 4170Vrms. Direct substitution is permissible only if the circuit design can operate safely at the lower isolation rating. Review the isolation voltage requirement in your application before proceeding.

Q: What is the difference between the 4N29SM and 4N29SMT&R?

A: Both parts are functionally equivalent Darlington optoisolators with single-channel output. The primary difference is packaging: the 4N29SM is supplied in Tube packaging for standard component handling, while the 4N29SMT&R is supplied in Tape & Reel format optimized for automated pick-and-place assembly. The 4N29SMT&R is manufactured by Isocom Components 2004 LTD rather than onsemi.

Q: Is the 4N29S still available for purchase?

A: The 4N29S is classified as obsolete. Inventory may be available through authorized distributors or secondary market sources, but long-term availability is not guaranteed. The 4N29SM and 4N29SMT&R are both in active production and represent the recommended path for new designs and production continuity.

Q: What are the compliance certifications for substitute parts?

A: The 4N29SM and 4N29SMT&R are both ROHS3 compliant and REACH unaffected. Both parts carry ECCN classification EAR99 and HTSUS code 8541.49.8000. Moisture sensitivity level is 1 (Unlimited) for both substitutes.

Q: Does the narrower operating temperature range of the 4N29SM affect compatibility?

A: The 4N29SM operates from -40°C to 100°C, compared to the 4N29S range of -55°C to 100°C. If your application requires operation below -40°C, the 4N29SM is not suitable. Verify the minimum operating temperature requirement of your circuit before selecting this substitute.