Littelfuse 0451005.MR Surface Mount Board Mount Fuse — Equivalent & Substitute Parts

Part Overview

The Littelfuse 0451005.MR is a 5 A, 125 V AC/DC surface mount board mount fuse in the NANO²® 451 series, packaged as a 2-SMD square end block with fast blow response time. This part is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and procurement. Active alternatives within the same electrical and mechanical specifications are available from Littelfuse and Bourns Inc.

Substiute Parts

0451005.MR

Littelfuse Inc.In Stock: 69220451005.MR Datasheet

Current PartRFQ

0448005.MR

Littelfuse Inc.In Stock: 407320448005.MR Datasheet

Parametric EquivalentRFQ

0451005.MRL

Littelfuse Inc.In Stock: 1051320451005.MRL Datasheet

Parametric EquivalentRFQ

0451005.MRSN

Littelfuse Inc.In Stock: 29350451005.MRSN Datasheet

Parametric EquivalentRFQ

0451005.NRL

Littelfuse Inc.In Stock: 35340451005.NRL Datasheet

Parametric EquivalentRFQ

0453005.MR

Littelfuse Inc.In Stock: 260950453005.MR Datasheet

Parametric EquivalentRFQ

0453005.NR

Littelfuse Inc.In Stock: 10930453005.NR Datasheet

Parametric EquivalentRFQ

SF-2410FP500T-2

Bourns Inc.In Stock: 6809SF-2410FP500T-2 Datasheet

DirectRFQ

SF-2410HI500T-2

Bourns Inc.In Stock: 5775SF-2410HI500T-2 Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility is determined by strict equivalence across the following parameters:

• Current Rating: 5 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)
• Physical Dimensions: 0.240" L x 0.106" W x 0.106" H (exact match required)
• Breaking Capacity: 50 A (exact match required)
• Operating Temperature Range: -55°C to 125°C (exact match required)

All substitute parts listed meet these criteria. Variations in melting I²t, DC cold resistance, and RoHS compliance status do not disqualify substitution but are noted for design consideration. Packaging format (Tape & Reel, Cut Tape, or Digi-Reel®) is a procurement variable and does not affect electrical or mechanical compatibility.

Parameter Comparison

Engineering Selection Recommendations

Primary Recommendation for Active Designs:

Use 0451005.MRL (Littelfuse NANO²® 451, Cut Tape & Digi-Reel® packaging). This part maintains identical electrical characteristics and thermal response to the obsolete 0451005.MR while offering ROHS3 compliance and active product status with the highest inventory availability (105,034 pcs).

Alternative Littelfuse Options:

• 0451005.MRSN or 0451005.NRL: Active NANO²® 451 variants in Tape & Reel packaging. Identical electrical performance to 0451005.MRL with lower inventory levels.
• 0453005.MR or 0453005.NR: Active NANO²® 453 series alternatives with identical electrical specifications. ROHS3 compliant and suitable for direct substitution.
• 0448005.MR: Active NANO²® 448 series with lower melting I²t (4.49 vs. 5.566) and slightly higher DC cold resistance (0.01531 Ω vs. 0.0125 Ω). Use only if thermal response characteristics are acceptable for the application.

Cross-Manufacturer Alternative:

• SF-2410FP500T-2 (Bourns SinglFuse™ SF-2410FP-T): Electrically equivalent with slightly higher melting I²t (6.175). ROHS3 compliant and active status. Suitable for designs requiring cross-manufacturer qualification.
• SF-2410HI500T-2 (Bourns SinglFuse™ SF-2410HI-T): Electrically equivalent with significantly higher melting I²t (50.308), indicating slower thermal response. Use only if application thermal profile permits slower fuse operation.

All recommended substitutes carry CSA, UL, or PSE approvals consistent with the original part.

Frequently Asked Questions (FAQ)

Q: Can I use 0451005.MRL as a direct replacement for the obsolete 0451005.MR?

A: Yes. Both parts share identical current rating (5 A), voltage ratings (125 V AC/DC), response time (Fast Blow), package type (2-SMD square end block), and physical dimensions. The primary difference is product status (active vs. obsolete) and RoHS compliance (ROHS3 vs. non-compliant). Electrical and mechanical compatibility is complete.

Q: What is the difference between 0451005.MRL and 0451005.MRSN?

A: Both are active NANO²® 451 fuses with identical electrical specifications. The difference is packaging format: 0451005.MRL uses Cut Tape & Digi-Reel®, while 0451005.MRSN uses Tape & Reel. Select based on your assembly equipment and procurement requirements.

Q: Why does 0448005.MR have a lower melting I²t value?

A: The 0448005.MR (NANO²® 448 series) has a melting I²t of 4.49 compared to 5.566 for the NANO²® 451 series. This indicates faster thermal response. Use 0448005.MR only if your circuit design accommodates faster fuse operation. For equivalent thermal behavior, use NANO²® 451 or NANO²® 453 variants.

Q: Can I substitute a Bourns fuse for a Littelfuse fuse?

A: Yes, if electrical and mechanical parameters match. SF-2410FP500T-2 and SF-2410HI500T-2 are electrically equivalent to the Littelfuse parts. However, SF-2410HI500T-2 has significantly higher melting I²t (50.308), indicating substantially slower thermal response. Verify application compatibility before cross-manufacturer substitution.

Q: Are all substitute parts RoHS compliant?

A: All active substitute parts listed (0451005.MRL, 0451005.MRSN, 0451005.NRL, 0453005.MR, 0453005.NR, SF-2410FP500T-2, SF-2410HI500T-2) are ROHS3 compliant. The original 0451005.MR is RoHS non-compliant. If RoHS compliance is required, use only active alternatives.

Q: What certifications do these fuses carry?

A: Littelfuse NANO²® series parts carry CSA, PSE, and UL approvals. Bourns SinglFuse™ parts carry cUL and UL approvals. All parts meet the same breaking capacity (50 A) and operating temperature range (-55°C to 125°C).