Littelfuse 0451012.MRSN Surface Mount Board Fuse Equivalent & Substitute Parts

Part Overview

The Littelfuse 0451012.MRSN is a 12A 125VAC surface mount board fuse in the NANO²® 451 series. This fast-blow fuse is designed for board-level circuit protection in applications requiring compact, high-reliability fusing. The part is active in production with full inventory availability. Substitute parts are identified when original stock is unavailable or when packaging format requirements differ while maintaining identical electrical and mechanical performance specifications.

Substiute Parts

0451012.MRSN

Littelfuse Inc.In Stock: 9910451012.MRSN Datasheet

Current PartRFQ

0476012.MR

Littelfuse Inc.In Stock: 10870476012.MR Datasheet

Parametric EquivalentRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the 0451012.MRSN is determined by the following critical parameters:

• Current Rating: 12 A (exact match required)
• Voltage Rating - AC: 125 V (exact match required)
• Mounting Type: Surface Mount (exact match required)
• Package / Case: 2-SMD, Square End Block (exact match required)
• Physical Dimensions: 0.240" L x 0.106" W x 0.106" H (exact match required)
• Response Time: Fast Blow (exact match required)
• Operating Temperature Range: -55°C ~ 125°C (exact match required)
• RoHS Compliance: ROHS3 Compliant (exact match required)

The substitute part 0476012.MR from Littelfuse Inc. meets all critical electrical and mechanical parameters. Differences in packaging format (Tape & Reel versus Cut Tape), series designation (NANO²® 451 versus NANO²® 476), and secondary specifications (breaking capacity, melting I²t, DC cold resistance) do not affect functional equivalence for board-level circuit protection applications.

Parameter Comparison

Engineering Selection Recommendations

Both the 0451012.MRSN and 0476012.MR are active production parts from Littelfuse Inc. with full regulatory compliance. Selection between these parts is determined by packaging requirements:

• 0451012.MRSN: Select when Tape & Reel packaging is required for automated assembly processes.
• 0476012.MR: Select when Cut Tape packaging is acceptable or preferred for manual assembly or lower-volume applications.

Both parts carry identical electrical ratings, thermal operating range, and regulatory certifications (ROHS3 Compliant, REACH Unaffected, EAR99 classification). Physical footprint and PCB mounting characteristics are identical, ensuring direct substitution at the board level.

Frequently Asked Questions (FAQ)

Q: Can 0476012.MR be used as a direct replacement for 0451012.MRSN on a PCB?

A: Yes. Both parts have identical current ratings (12 A), voltage ratings (125 VAC), physical dimensions (0.240" L x 0.106" W x 0.106" H), package type (2-SMD, Square End Block), and response characteristics (Fast Blow). PCB footprints and mounting requirements are identical.

Q: What is the difference between Tape & Reel and Cut Tape packaging?

A: Tape & Reel packaging supplies components on continuous carrier tape wound on reels, optimized for high-speed automated pick-and-place assembly. Cut Tape packaging supplies the same components on shorter tape segments, suitable for manual assembly or lower-volume production runs. Electrical and mechanical specifications are unchanged.

Q: Are there any thermal or environmental differences between these parts?

A: No. Both parts operate across the identical temperature range (-55°C ~ 125°C) and carry the same Moisture Sensitivity Level (MSL 1, Unlimited). Environmental compliance is identical (ROHS3 Compliant, REACH Unaffected).

Q: Can these fuses be used in DC applications?

A: The 0451012.MRSN is rated for 125VAC. The 0476012.MR is rated for both 125VAC and 125VDC. For DC circuit protection, the 0476012.MR is the appropriate selection.

Q: What is the breaking capacity difference between these parts?

A: The 0451012.MRSN has a breaking capacity of 35A at rated voltage. The 0476012.MR has a breaking capacity of 100A AC and 300A DC at rated voltage. Breaking capacity indicates the maximum fault current the fuse can safely interrupt. Higher breaking capacity provides enhanced protection in high-fault-current environments.