Littelfuse 0451.750MR Surface Mount Fuse Equivalent & Substitute Parts

Part Overview

The Littelfuse 0451.750MR is a 750 mA, 125 V AC/DC surface mount board fuse in the NANO²® 451 series with a 2-SMD square end block package. This part is currently obsolete with limited inventory (2,840 pcs). Equivalent and substitute parts are necessary to maintain design continuity and ensure component availability for new production runs and field replacements.

Substiute Parts

0451.750MR

Littelfuse Inc.In Stock: 29260451.750MR Datasheet

Current PartRFQ

0451.750MRL

Littelfuse Inc.In Stock: 552290451.750MRL Datasheet

DirectRFQ

0448.750MR

Littelfuse Inc.In Stock: 73420448.750MR Datasheet

Parametric EquivalentRFQ

0451.750NRL

Littelfuse Inc.In Stock: 100720451.750NRL Datasheet

Parametric EquivalentRFQ

0453.750MR

Littelfuse Inc.In Stock: 102530453.750MR Datasheet

Parametric EquivalentRFQ

0453.750NR

Littelfuse Inc.In Stock: 10990453.750NR Datasheet

Parametric EquivalentRFQ

SF-2410FP075T-2

Bourns Inc.In Stock: 2761SF-2410FP075T-2 Datasheet

DirectRFQ

SF-2410HI075T-2

Bourns Inc.In Stock: 9089SF-2410HI075T-2 Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility is determined by the following critical parameters:

• Current Rating: 750 mA (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: 50A (exact match required)
• Operating Temperature Range: -55°C ~ 125°C (exact match required)
• Approval Agencies: CSA and/or UL certification required

Substitute parts are grouped into two categories:

Direct Manufacturer Equivalents (Littelfuse NANO²® Series): Parts with identical electrical and mechanical specifications, differing only in packaging format (bulk vs. tape & reel) or series designation within the same manufacturer's product line.

Cross-Manufacturer Equivalents (Bourns SinglFuse™ Series): Parts from alternative manufacturers meeting all critical electrical and mechanical parameters with equivalent performance characteristics.

Parameter Comparison

Engineering Selection Recommendations

Primary Recommendation: 0451.750MRL (Littelfuse NANO²® 451)

This part is the direct equivalent of the obsolete 0451.750MR, maintaining identical electrical characteristics (Melting I²t: 0.185, DC Cold Resistance: 0.245 Ω) and mechanical specifications. It is active in production with ROHS3 compliance and high inventory availability (55,200 pcs). The only difference is packaging format (Tape & Reel vs. bulk), which does not affect electrical performance or board-level compatibility.

Secondary Recommendations: 0451.750NRL, 0453.750MR, 0453.750NR (Littelfuse NANO²® Series)

These parts maintain identical electrical and mechanical specifications to the original part. All are active in production with ROHS3 compliance. Selection among these alternatives depends on packaging availability and supply chain requirements.

Alternative Recommendation: 0448.750MR (Littelfuse NANO²® 448)

This part meets all critical electrical and mechanical parameters. Melting I²t (0.206) and DC Cold Resistance (0.2475 Ω) show minor variations within acceptable engineering tolerances for this fuse category. Active production status and ROHS3 compliance support its use as a secondary alternative.

Cross-Manufacturer Alternatives: SF-2410FP075T-2, SF-2410HI075T-2 (Bourns SinglFuse™ Series)

Both Bourns parts meet all critical electrical and mechanical specifications with CSA and UL certifications. Melting I²t values differ (0.3761 and 1.2632 respectively), reflecting different thermal response characteristics within the fast-blow category. These parts are suitable for applications where cross-manufacturer sourcing is acceptable. SF-2410HI075T-2 carries REACH Affected status, requiring compliance verification for regulated applications.

Frequently Asked Questions (FAQ)

Q: Can I use 0451.750MRL as a direct replacement for the obsolete 0451.750MR?

A: Yes. The 0451.750MRL is electrically and mechanically identical to the 0451.750MR. The only difference is packaging format (Tape & Reel vs. bulk). Both parts have identical current rating, voltage rating, response time, breaking capacity, and physical dimensions. Board-level performance is equivalent.

Q: What is the difference between the Littelfuse NANO²® 451, 448, and 453 series fuses?

A: All three series meet the specified electrical and mechanical parameters for this 750 mA, 125 V application. The series designation reflects internal design variations. The 0448.750MR shows slightly different thermal characteristics (Melting I²t: 0.206 vs. 0.185). All are approved by CSA and UL and suitable for equivalent applications.

Q: Can I substitute a Bourns SinglFuse™ part for a Littelfuse NANO²® part?

A: Yes, provided all critical parameters match: 750 mA current rating, 125 V AC/DC voltage rating, fast-blow response, 50A breaking capacity, and 2-SMD square end block package. Both SF-2410FP075T-2 and SF-2410HI075T-2 meet these requirements. Verify that your application design does not depend on specific thermal response characteristics, as Melting I²t values differ between manufacturers.

Q: What does ROHS3 compliance mean for fuse selection?

A: ROHS3 compliance indicates the part meets Restriction of Hazardous Substances Directive requirements. The original 0451.750MR is RoHS non-compliant. All recommended substitutes are ROHS3 compliant, making them suitable for applications requiring regulatory compliance with current environmental standards.

Q: Does packaging format (bulk vs. Tape & Reel) affect electrical performance?

A: No. Packaging format affects only handling, storage, and assembly processes. Electrical and mechanical specifications remain identical regardless of whether the part is supplied in bulk or on Tape & Reel. Selection should be based on manufacturing process requirements and supply chain logistics.

Q: What is the significance of DC Cold Resistance variation among substitute parts?

A: DC Cold Resistance affects the fuse's thermal response and I²t characteristics. Minor variations (0.1666 Ω to 0.2475 Ω) are within acceptable engineering tolerances for this fuse category and do not prevent substitution. However, applications with strict thermal response requirements should verify that the selected substitute meets specific I²t performance criteria.

Q: Are all substitute parts certified by CSA and UL?

A: Yes. All recommended substitute parts carry CSA and/or UL certification, meeting the approval agency requirements of the original 0451.750MR. This ensures compliance with safety standards for board-mounted fuse applications.