MOC3042FM Equivalent & Substitute Parts

Part Overview

The MOC3042FM is a 7.5kV optoisolator with triac output manufactured by onsemi in a 6-SMD surface mount package. This component provides galvanic isolation between control and power circuits with zero-crossing detection capability. The MOC3042FM is classified as obsolete, making identification of suitable substitute components essential for ongoing design support and production continuity.

Substiute Parts

MOC3042FM

onsemiIn Stock: 695MOC3042FM Datasheet

Current PartRFQ

MOC3042SM

onsemiIn Stock: 1629MOC3042SM Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the MOC3042FM is determined by the following critical parameters:

• Output Type: Must be Triac output for direct functional replacement
• Number of Channels: Must be 1 channel to match circuit topology
• Zero Crossing Circuit: Must include zero-crossing detection
• Mounting Type: Must be Surface Mount to maintain PCB compatibility
• Package / Case: Must be 6-SMD, Gull Wing for footprint compatibility
• Voltage - Off State: Must be rated for 400 V operation
• Current Specifications: LED trigger current (Ift), hold current (Ih), and forward current (If) must be compatible with existing circuit design

The MOC3042SM qualifies as a substitute based on matching all critical parameters. However, the isolation voltage rating differs between the two parts, requiring engineering evaluation for specific application requirements.

Parameter Comparison

Engineering Selection Recommendations

The MOC3042SM is the active production substitute for the obsolete MOC3042FM. Both components share identical mechanical compatibility (6-SMD, Gull Wing package) and core functional specifications (triac output, single channel, zero-crossing detection, 400V off-state rating, and matching current parameters).

The primary technical difference is isolation voltage rating: MOC3042FM specifies 7500Vpk while MOC3042SM specifies 4170Vrms. Application circuits designed for the MOC3042FM must verify that the lower isolation voltage of the MOC3042SM meets system safety and regulatory requirements.

The MOC3042SM offers additional advantages for new designs: active product status ensures ongoing availability, ROHS3 compliance supports environmental regulations, and UL approval provides third-party validation. The specified operating temperature range (-40°C ~ 85°C) and static dV/dt rating (1kV/µs) provide additional design parameters for thermal and transient performance evaluation.

Frequently Asked Questions (FAQ)

Q: Can MOC3042SM directly replace MOC3042FM in existing designs?

A: Mechanical and functional compatibility is confirmed. The isolation voltage difference (7500Vpk vs 4170Vrms) requires verification against application safety margins and regulatory requirements before implementation.

Q: What is the significance of the isolation voltage difference?

A: Isolation voltage determines the maximum voltage differential that can be safely applied across the optoisolator without breakdown. The MOC3042FM provides higher isolation capability. Applications requiring 7500Vpk isolation must confirm that 4170Vrms isolation is adequate for their specific circuit topology and safety standards.

Q: Are the current specifications identical between these parts?

A: Yes. LED trigger current (10mA max), hold current (400µA typical), and forward current (60mA max) are identical, ensuring compatible circuit operation.

Q: Does package compatibility guarantee direct substitution?

A: Package compatibility (6-SMD, Gull Wing) confirms PCB footprint and reflow soldering compatibility. Electrical parameter verification remains necessary before production implementation.

Q: What compliance advantages does MOC3042SM provide?

A: MOC3042SM carries ROHS3 compliance and UL approval, supporting regulatory requirements for many industrial and consumer applications. MOC3042FM compliance status is not specified.