Littelfuse 0451004.NRL Surface Mount Board Mount Fuse Equivalent & Substitute Parts

Part Overview

The Littelfuse 0451004.NRL is a 4 A, 125 V AC/DC surface mount board mount fuse in the NANO²® 451 series. This fast-blow fuse is designed for circuit protection in applications requiring 2-SMD, square end block packaging. The part is active and in production with full compliance to CSA, PSE, and UL approval agencies. Equivalent and substitute parts are identified to support procurement flexibility, inventory management, and design alternatives across compatible fuse series and manufacturers.

Substiute Parts

0451004.NRL

Littelfuse Inc.In Stock: 51940451004.NRL Datasheet

Current PartRFQ

0448004.MR

LittelfuseIn Stock: 186850448004.MR Datasheet

Parametric EquivalentRFQ

0451004.MRL

Littelfuse Inc.In Stock: 421690451004.MRL Datasheet

Parametric EquivalentRFQ

0453004.MR

Littelfuse Inc.In Stock: 213470453004.MR Datasheet

Parametric EquivalentRFQ

SF-2410FP400T-2

Bourns Inc.In Stock: 2969SF-2410FP400T-2 Datasheet

DirectRFQ

SF-2410HI400T-2

Bourns Inc.In Stock: 2703SF-2410HI400T-2 Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the 0451004.NRL is determined by the following critical parameters:

• Current Rating: 4 A (exact match required)
• Voltage Rating: 125 V AC and 125 V DC (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)
• Breaking Capacity @ Rated Voltage: 50 A (exact match required)
• Operating Temperature Range: -55°C to 125°C (exact match required)
• Approval Agencies: CSA, PSE, UL (minimum compliance required)

All identified substitute parts meet these electrical and mechanical parameters. Differences in DC cold resistance and melting I²t values are within acceptable tolerances for this product category and do not affect substitution eligibility. Packaging format variations (Tape & Reel vs. Cut Tape & Digi-Reel®) are logistical considerations and do not affect electrical compatibility.

Parameter Comparison

Engineering Selection Recommendations

All identified substitute parts maintain active product status and meet the electrical and mechanical requirements of the 0451004.NRL. Selection among these alternatives should be based on the following factors:

Littelfuse NANO²® Series (0451004.NRL, 0448004.MR, 0451004.MRL, 0453004.MR): These parts share identical electrical specifications and are approved by CSA, PSE, and UL. The 0451004.MRL offers the same series and specifications as the main part but in Cut Tape & Digi-Reel® packaging, suitable for applications requiring smaller order quantities or alternative handling formats. The 0448004.MR and 0453004.MR represent alternative series within the NANO²® family with equivalent performance characteristics.

Bourns SinglFuse™ Series (SF-2410FP400T-2, SF-2410HI400T-2): These parts are approved by cUL and UL and meet all electrical and mechanical parameters. The SF-2410HI400T-2 carries REACH Affected status, whereas the SF-2410FP400T-2 is REACH Unaffected. Both are suitable for direct substitution where cross-manufacturer compatibility is acceptable.

Compliance Considerations: All parts are ROHS3 compliant and carry MSL 1 (Unlimited) moisture sensitivity ratings. Littelfuse parts include PSE approval, while Bourns parts carry cUL certification in addition to UL approval.

Frequently Asked Questions (FAQ)

Q: Can the 0451004.MRL be used as a direct replacement for the 0451004.NRL?

A: Yes. Both parts are from the Littelfuse NANO²® 451 series with identical electrical specifications, approvals, and mechanical dimensions. The difference is packaging format: 0451004.NRL is supplied in Tape & Reel (TR), while 0451004.MRL is supplied in Cut Tape (CT) & Digi-Reel®. Electrical performance and PCB compatibility are identical.

Q: What is the difference between the Littelfuse NANO²® series substitutes (0448004.MR, 0451004.MRL, 0453004.MR)?

A: All three parts meet the same electrical and mechanical requirements as the 0451004.NRL. They differ only in series designation (448, 451, 453) and minor variations in melting I²t values (3.97, 3.152, 3.152 respectively). These variations are within acceptable tolerances and do not affect substitution eligibility.

Q: Can Bourns SinglFuse™ parts replace Littelfuse NANO²® fuses?

A: Yes. The SF-2410FP400T-2 and SF-2410HI400T-2 meet all electrical and mechanical parameters of the 0451004.NRL. Both are approved by UL and cUL. The primary consideration is cross-manufacturer qualification in your design documentation and supply chain requirements.

Q: What is the significance of the DC cold resistance differences among these parts?

A: DC cold resistance values range from 0.015 to 0.021 Ohms across all substitutes. These variations are within acceptable tolerances for this fuse category and do not affect circuit protection performance or compatibility.

Q: Does the SF-2410HI400T-2 REACH Affected status affect substitution eligibility?

A: REACH Affected status indicates the part contains substances of concern under REACH regulations. This is a compliance and supply chain consideration, not an electrical or mechanical compatibility issue. Selection should be based on your application's regulatory requirements and supply chain policies.

Q: Are there dimensional differences between Littelfuse and Bourns substitutes?

A: Littelfuse parts measure 0.240" L x 0.106" W x 0.106" H (6.10mm x 2.69mm x 2.69mm). Bourns parts measure 0.240" L x 0.102" W x 0.102" H (6.10mm x 2.59mm x 2.59mm). Both conform to the 2-SMD, square end block package specification and are mechanically compatible with standard PCB footprints designed for this package type.

Q: Which substitute offers the best inventory availability?

A: Inventory levels are provided for reference: 0451004.MRL (42,100 pcs), 0448004.MR (18,596 pcs), 0453004.MR (21,300 pcs), SF-2410FP400T-2 (2,871 pcs), and SF-2410HI400T-2 (2,604 pcs). Availability should be verified with your supplier for current stock status.