MOC3051FM Optoisolator Triac Output - Equivalent & Substitute Parts

Part Overview

The MOC3051FM is a 7.5kV isolation optoisolator with triac output manufactured by onsemi in 6-SMD surface mount packaging. This component is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and production continuity. The MOC3051FM serves applications requiring galvanic isolation in triac-driven circuits with high voltage isolation requirements.

Substiute Parts

MOC3051FM

onsemiIn Stock: 849MOC3051FM Datasheet

Current PartRFQ

MOC3051SM

Fairchild SemiconductorIn Stock: 23591MOC3051SM Datasheet

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EL3051

Everlight Electronics Co LtdIn Stock: 52485EL3051 Datasheet

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EL3052

Everlight Electronics Co LtdIn Stock: 151994EL3052 Datasheet

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EL3053

Everlight Electronics Co LtdIn Stock: 17973EL3053 Datasheet

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IS3052G

Isocom Components 2004 LTDIn Stock: 858IS3052G Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the MOC3051FM is determined by the following critical parameters:

• Output Type: Must be Triac
• Number of Channels: Must be 1
• Zero Crossing Circuit: Must be No
• Voltage - Off State: Must be 600 V
• Static dV/dt (Min): Must be 1kV/µs or greater
• Voltage - Isolation: Must meet or exceed 5000Vrms (equivalent to 7071Vpk minimum)
• Current - LED Trigger (Ift) (Max): Must be 15mA or less
• Current - Hold (Ih): Must be compatible with circuit requirements
• Operating Temperature Range: Must encompass or exceed -40°C ~ 85°C
• Mounting Type and Package: Surface mount (6-SMD) preferred; through-hole (6-DIP) acceptable with board redesign

Substitute parts are grouped into two categories:

Category A - Surface Mount Direct Replacement (6-SMD)

• MOC3051SM: Active product, maintains SMD form factor

Category B - Through-Hole Alternative (6-DIP)

• EL3051, EL3052, EL3053, IS3052G: Active products, require PCB layout modification

Parameter Comparison

Engineering Selection Recommendations

MOC3051SM (Fairchild Semiconductor)

MOC3051SM is the preferred direct replacement for the obsolete MOC3051FM. Both components share identical surface mount 6-SMD packaging, eliminating PCB redesign requirements. MOC3051SM maintains active product status with UR approval certification. The isolation voltage specification of 4170Vrms is lower than the original 7500Vpk; applications requiring the full 7500Vpk isolation margin must conduct circuit analysis to confirm adequacy at 4170Vrms. LED trigger current and hold current parameters are compatible with the original design.

EL3051, EL3052, EL3053 (Everlight Electronics)

These through-hole 6-DIP alternatives provide isolation voltage of 5000Vrms with active product status and comprehensive safety certifications (CSA, DEMKO, FIMKO, NEMKO, SEMKO, UL). EL3051 and EL3052 differ in LED trigger current specifications (15mA and 10mA respectively), while EL3053 specifies 5mA trigger current. All three support extended operating temperature range (-55°C ~ 100°C) and RoHS3 compliance. PCB layout modification is required for through-hole mounting.

IS3052G (Isocom Components)

IS3052G offers 5000Vrms isolation with active product status and UL/VDE certifications. The 6-DIP package uses 0.400" (10.16mm) pitch, differing from standard 0.300" (7.62mm) DIP spacing. This component requires PCB redesign and footprint verification. Operating temperature range extends to 100°C. Current - DC Forward (If) maximum is specified at 50mA, lower than the 60mA original specification.

Frequently Asked Questions (FAQ)

Q: Can MOC3051SM directly replace MOC3051FM without PCB modification?

A: Yes. Both components use 6-SMD surface mount packaging with identical pinout and footprint. No PCB layout changes are required. However, the isolation voltage specification differs (4170Vrms vs. 7500Vpk); circuit analysis must confirm this meets application requirements.

Q: What is the key difference between EL3051, EL3052, and EL3053?

A: The three Everlight components differ in LED trigger current (Ift) specifications: EL3051 at 15mA, EL3052 at 10mA, and EL3053 at 5mA. Selection depends on the drive circuit's current capability. All three share identical isolation voltage (5000Vrms), hold current characteristics, and through-hole 6-DIP packaging.

Q: Why does IS3052G have a different DIP pitch (0.400" vs. 0.300")?

A: IS3052G uses 0.400" (10.16mm) DIP spacing instead of the standard 0.300" (7.62mm) spacing. This requires PCB footprint modification and cannot be used as a drop-in replacement without board redesign.

Q: Are all substitute parts RoHS compliant?

A: EL3051, EL3052, EL3053, and IS3052G are all RoHS3 compliant. MOC3051SM RoHS status is not specified in available documentation.

Q: What isolation voltage should I use for circuit design if switching from MOC3051FM to a substitute?

A: Use the specified isolation voltage of the selected substitute part. MOC3051SM specifies 4170Vrms; EL3051, EL3052, EL3053, and IS3052G specify 5000Vrms. Do not assume equivalence to the original 7500Vpk specification. Conduct isolation margin analysis based on your application's voltage stress conditions.

Q: Can I use a through-hole substitute (EL-series or IS3052G) in a design originally specified for MOC3051FM surface mount?

A: Through-hole substitutes require PCB redesign and cannot be used without modifying the board layout and footprint. Evaluate cost and schedule impact of PCB revision against component availability and lead time.

Q: Which substitute offers the best compliance certifications?

A: EL3051, EL3052, and EL3053 provide the most comprehensive safety certifications (CSA, DEMKO, FIMKO, NEMKO, SEMKO, UL). IS3052G offers UL and VDE certifications. MOC3051SM specifies UR approval only.