4N26SD Optoisolator Equivalent & Substitute Parts

Part Overview

The 4N26SD 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.

The 4N26SD serves as a single-channel optoisolator with transistor output, designed for DC input applications requiring galvanic isolation. Substitute parts must maintain compatibility across isolation voltage, output characteristics, and package form factor while accounting for variations in electrical performance and product status.

Substiute Parts

4N26SD

onsemiIn Stock: 149394N26SD Datasheet

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4N26SR2M

onsemiIn Stock: 224384N26SR2M Datasheet

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4N26-X009T

Vishay Semiconductor Opto DivisionIn Stock: 124794N26-X009T Datasheet

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4N26S

Fairchild SemiconductorIn Stock: 90534N26S Datasheet

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4N26S-TA

Lite-On Inc.In Stock: 11164N26S-TA Datasheet

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4N26S-TA1

Lite-On Inc.In Stock: 10554N26S-TA1 Datasheet

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4N26SMT&R

Isocom Components 2004 LTDIn Stock: 8024N26SMT&R Datasheet

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4N26XSM

Isocom Components 2004 LTDIn Stock: 7574N26XSM Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the 4N26SD is determined by the following critical parameters:

• Isolation Voltage Rating: Minimum 5300Vrms or equivalent isolation performance
• Output Configuration: Transistor with base output required
• Package Type: 6-SMD, Gull Wing surface mount form factor
• Number of Channels: Single channel only
• Input Type: DC input compatibility
• Current Transfer Ratio: Minimum 20% @ 10mA
• Vce Saturation: Maximum 500mV
• Operating Temperature Range: Support for -55°C to 100°C minimum

Substitute parts are grouped into two categories:

Direct Substitutes maintain all critical electrical parameters and isolation voltage specifications equivalent to or exceeding the 4N26SD.

Compatible Alternatives provide functional equivalence with variations in isolation voltage, output voltage rating, or current handling capacity, suitable for applications where the specific parameter variance does not impact system performance.

Parameter Comparison

Engineering Selection Recommendations

Primary Substitutes for High-Isolation Applications:

The 4N26XSM (Isocom Components 2004 LTD) and 4N26S (Fairchild Semiconductor) maintain the 5300Vrms isolation voltage specification of the 4N26SD. The 4N26XSM is currently active and ROHS3 compliant, making it the preferred choice for new designs. The 4N26S, while obsolete, provides electrical equivalence for legacy system support.

Secondary Substitute for Reduced-Isolation Requirements:

The 4N26-X009T (Vishay Semiconductor Opto Division) provides 5000Vrms isolation, slightly below the 4N26SD specification but within the 4N26 base product family. This part is active and ROHS3 compliant. The higher maximum output voltage (70V versus 30V) and specified output current (50mA) offer expanded application flexibility. Selection of this part requires confirmation that 5000Vrms isolation meets system requirements.

Lower-Isolation Alternatives:

The 4N26S-TA and 4N26S-TA1 (Lite-On Inc.) provide 1500Vrms isolation, significantly reduced from the 4N26SD. Both parts are active and ROHS3 compliant. These substitutes are suitable only for applications where isolation voltage requirements are 1500Vrms or lower. Higher output current capability (100mA) may benefit certain circuit topologies.

Limited Compatibility Substitute:

The 4N26SR2M (onsemi) reduces isolation voltage to 4170Vrms and forward current to 60mA. This part is active but has a narrower operating temperature range (-40°C to 100°C versus -55°C to 100°C). Selection requires confirmation of temperature range compatibility.

Non-Recommended Substitute:

The 4N26SMT&R (Isocom Components 2004 LTD) specifies isolation as 7.5Vpk, which is incompatible with the 4N26SD isolation voltage class and represents a different product category. This part is not suitable for direct substitution.

Frequently Asked Questions (FAQ)

Q: Can the 4N26SR2M replace the 4N26SD in all applications?

A: The 4N26SR2M provides 4170Vrms isolation versus the 4N26SD's 5300Vrms. Substitution is valid only if your application requires isolation voltage of 4170Vrms or lower. Additionally, the operating temperature range is -40°C to 100°C, narrower than the 4N26SD's -55°C to 100°C. Confirm both isolation voltage and temperature requirements before selection.

Q: What is the difference between the 4N26XSM and 4N26S?

A: Both parts maintain 5300Vrms isolation voltage and are electrically equivalent. The primary difference is product status: 4N26XSM is active and ROHS3 compliant, while 4N26S is obsolete. For new designs, the 4N26XSM is recommended. For legacy system support, the 4N26S provides direct electrical equivalence.

Q: Why is the 4N26-X009T listed as a substitute if it has lower isolation voltage?

A: The 4N26-X009T provides 5000Vrms isolation, which is 300Vrms below the 4N26SD specification. It is included as a compatible alternative for applications where 5000Vrms isolation is sufficient. This part offers advantages including higher maximum output voltage (70V) and specified output current (50mA). Substitution requires confirmation that reduced isolation voltage meets system requirements.

Q: Are the 4N26S-TA and 4N26S-TA1 suitable replacements?

A: The 4N26S-TA and 4N26S-TA1 are not direct replacements. Both provide only 1500Vrms isolation, significantly lower than the 4N26SD's 5300Vrms. These parts are suitable only for applications designed for 1500Vrms isolation or lower. They offer higher output current capability (100mA) but cannot be used in circuits requiring the full 5300Vrms isolation specification.

Q: What does ROHS3 compliance mean for component selection?

A: ROHS3 compliance indicates the part meets Restriction of Hazardous Substances Directive requirements. Most active substitute parts listed (4N26SR2M, 4N26-X009T, 4N26S-TA, 4N26S-TA1, 4N26XSM, 4N26SMT&R) are ROHS3 compliant. The original 4N26SD does not specify RoHS status. For new designs subject to RoHS requirements, select from the ROHS3 compliant alternatives.

Q: Can I use the 4N26SMT&R as a substitute?

A: No. The 4N26SMT&R specifies 7.5Vpk isolation, which is fundamentally incompatible with the 4N26SD's 5300Vrms isolation class. This part represents a different product category and is not suitable for direct substitution.

Q: What packaging options are available for substitutes?

A: All substitute parts maintain the 6-SMD, Gull Wing surface mount package form factor, ensuring mechanical compatibility with the 4N26SD. Packaging format (Tape & Reel or Tube) varies by manufacturer and supplier but does not affect electrical or mechanical compatibility in the circuit.