Littelfuse 0451.630MRSN Surface Mount Board Fuse Equivalent & Substitute Parts

Part Overview

The Littelfuse 0451.630MRSN is a 630 mA, 125 V AC surface mount board fuse in the NANO²® 451 series. This fast-blow fuse is designed for board-level protection in electronic circuits requiring AC voltage ratings. The part is currently active in production with full RoHS3 compliance and CSA/UR approvals. Equivalent substitute parts are available within the NANO²® fuse family to support procurement flexibility, inventory management, and design continuity across compatible applications.

Substiute Parts

0451.630MRSN

Littelfuse Inc.In Stock: 6960451.630MRSN Datasheet

Current PartRFQ

0448.630MR

Littelfuse Inc.In Stock: 30680448.630MR Datasheet

Parametric EquivalentRFQ

0451.630MRL

Littelfuse Inc.In Stock: 112530451.630MRL Datasheet

Parametric EquivalentRFQ

0453.630MR

LittelfuseIn Stock: 17970453.630MR Datasheet

Parametric EquivalentRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitute parts for the 0451.630MRSN are qualified based on the following critical parameters that must remain constant for direct substitution:

• Current Rating: 630 mA (exact match required)
• Voltage Rating - AC: 125 V (exact match required)
• Response Time: Fast Blow (exact match required)
• Mounting Type: Surface Mount (exact match required)
• Package / Case: 2-SMD, Square End Block (exact match required)
• Size / Dimension: 0.240" L x 0.106" W x 0.106" H (exact match required)
• Fuse Type: Board Mount (Cartridge Style Excluded) (exact match required)
• Breaking Capacity @ Rated Voltage: 50A (exact match required)
• Operating Temperature Range: -55°C ~ 125°C (exact match required)
• RoHS Status: ROHS3 Compliant (exact match required)

The substitute parts listed below meet all these criteria and are therefore electrically and mechanically interchangeable with the main part number.

Parameter Comparison

Engineering Selection Recommendations

All substitute parts listed are active products with full RoHS3 compliance and regulatory approvals suitable for board-level fuse applications. Selection among these equivalents should be based on:

Approval Agency Alignment: The main part 0451.630MRSN carries CSA and UR approvals. Substitute parts 0448.630MR, 0451.630MRL, and 0453.630MR carry CSA and UL approvals. Verify that the target application's regulatory requirements align with the available certifications.

DC Voltage Rating: The main part 0451.630MRSN is rated for AC voltage only. Substitute parts 0448.630MR, 0451.630MRL, and 0453.630MR include DC voltage ratings of 125 V. For applications requiring DC protection, the substitute parts provide expanded capability.

Melting I²t and DC Cold Resistance: The 0448.630MR exhibits a lower melting I²t value (0.121 versus 0.143) and lower DC cold resistance (0.2821 versus 0.305 Ohms). These differences may affect thermal response characteristics in specific circuit designs and should be evaluated against application requirements.

Inventory and Series Availability: The 0451.630MRL offers the highest inventory availability (11,231 pcs) and maintains the same NANO²® 451 series designation as the main part. The 0448.630MR (NANO²® 448 series) and 0453.630MR (NANO²® 453 series) provide alternative series options with different thermal characteristics.

Frequently Asked Questions (FAQ)

Q: Can the 0448.630MR be used as a direct replacement for the 0451.630MRSN?

A: The 0448.630MR is electrically and mechanically compatible for board-level mounting. However, it exhibits different melting I²t (0.121 versus 0.143) and DC cold resistance (0.2821 versus 0.305 Ohms) characteristics. Additionally, it carries UL approval rather than UR approval. Verify that these differences align with your application's thermal and regulatory requirements before substitution.

Q: What is the difference between the main part and the 0451.630MRL?

A: The 0451.630MRL is functionally equivalent to the 0451.630MRSN. Both are NANO²® 451 series fuses with identical electrical parameters, thermal characteristics, and physical dimensions. The primary difference is that the 0451.630MRL includes a DC voltage rating of 125 V, whereas the main part is AC-rated only. The 0451.630MRL carries UL approval instead of UR approval.

Q: Are all substitute parts available in the same packaging format?

A: Yes. All parts listed—0451.630MRSN, 0448.630MR, 0451.630MRL, and 0453.630MR—are supplied in Tape & Reel (TR) packaging and feature identical 2-SMD, Square End Block case styles with matching physical dimensions of 0.240" L x 0.106" W x 0.106" H.

Q: Which substitute part should I select for maximum inventory availability?

A: The 0451.630MRL offers the highest inventory level at 11,231 pieces in stock. This part maintains the same NANO²® 451 series designation and thermal characteristics as the main part while providing expanded DC voltage capability.

Q: Do all substitute parts meet RoHS3 compliance?

A: Yes. All parts—0451.630MRSN, 0448.630MR, 0451.630MRL, and 0453.630MR—are ROHS3 compliant with Moisture Sensitivity Level 1 (Unlimited) ratings.

Q: What approval agencies certify these fuses?

A: The main part 0451.630MRSN carries CSA and UR approvals. The substitute parts 0448.630MR, 0451.630MRL, and 0453.630MR carry CSA and UL approvals. Confirm that your application's regulatory framework accepts the available certifications before final part selection.