Littelfuse 045104.6NRL Surface Mount Board Mount Fuse Equivalent & Substitute Parts

Part Overview

The Littelfuse 045104.6NRL is a 4.6 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 compact SMD packaging with 2-SMD square end block configuration. The part is active in production status and widely used in consumer electronics, industrial equipment, and power distribution circuits where space constraints and high-density PCB layouts are critical.

Equivalent and substitute parts become necessary when the primary part number experiences supply constraints, inventory limitations, or when design flexibility allows for alternative manufacturers or packaging formats that maintain electrical and mechanical compatibility.

Substiute Parts

045103.5NRL

Littelfuse Inc.In Stock: 1055045103.5NRL Datasheet

Current PartRFQ

044803.5MR

Littelfuse Inc.In Stock: 1541044803.5MR Datasheet

Parametric EquivalentRFQ

045103.5MRL

Littelfuse Inc.In Stock: 9642045103.5MRL Datasheet

Parametric EquivalentRFQ

045303.5MR

Littelfuse Inc.In Stock: 5495045303.5MR Datasheet

Parametric EquivalentRFQ

SF-2410FP350T-2

Bourns Inc.In Stock: 3027SF-2410FP350T-2 Datasheet

DirectRFQ

SF-2410HI350T-2

Bourns Inc.In Stock: 2842SF-2410HI350T-2 Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the 045104.6NRL is determined by strict equivalence across the following critical parameters:

• Current Rating: 4.6 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)
• RoHS Status: ROHS3 Compliant (exact match required)

Substitute parts are grouped into two categories:

Parametric Equivalents (Littelfuse Manufacturer): Parts 044804.6MR, 045104.6MRL, and 045304.6MR meet all critical electrical and mechanical parameters. These parts differ only in series designation (NANO²® 448, 451, or 453) and packaging format (Tape & Reel versus Cut Tape & Digi-Reel®), which do not affect functional compatibility in circuit applications.

Direct Manufacturer Equivalents (Bourns Inc.): Parts SF-2410FP350T-2 and SF-2410HI350T-2 are cross-manufacturer alternatives that satisfy all critical electrical specifications and mechanical dimensions. These parts are manufactured by Bourns Inc. and carry equivalent UL and cUL certifications.

Parameter Comparison

Engineering Selection Recommendations

All listed substitute parts maintain active product status and comply with ROHS3 requirements. Selection among equivalent options is based on availability, packaging preference, and certification requirements specific to the end application.

Littelfuse Parametric Equivalents (044804.6MR, 045104.6MRL, 045304.6MR): These parts are recommended when Littelfuse manufacturer continuity is required or when existing supply chain relationships favor single-source qualification. The 045104.6MRL offers the highest inventory availability (9,535 pcs) and is available in Cut Tape & Digi-Reel® packaging, suitable for lower-volume production runs or prototype applications. The 044804.6MR and 045304.6MR are available in Tape & Reel format for high-volume automated assembly.

Bourns Inc. Direct Equivalents (SF-2410FP350T-2, SF-2410HI350T-2): These parts are recommended when cross-manufacturer qualification is acceptable and when Bourns supply chain availability is advantageous. Both parts carry cUL and UL certifications. The SF-2410HI350T-2 carries REACH Affected status, which may require additional compliance documentation in certain regulatory jurisdictions.

Frequently Asked Questions (FAQ)

Q: Can I substitute the 045104.6NRL with any of the listed parts without PCB redesign?

A: Yes. All listed substitute parts share identical electrical ratings (4.6 A, 125 V AC/DC, Fast Blow response), identical mounting type (Surface Mount), and identical package designation (2-SMD, Square End Block). The Littelfuse parametric equivalents (044804.6MR, 045104.6MRL, 045304.6MR) have identical footprint dimensions. The Bourns parts (SF-2410FP350T-2, SF-2410HI350T-2) have slightly reduced width and height dimensions (0.102" versus 0.106"), but remain compatible with standard 2-SMD square end block footprints used in PCB design.

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

A: Tape & Reel (TR) packaging is supplied on continuous carrier tape wound on a reel, optimized for high-speed automated pick-and-place assembly. Cut Tape (CT) & Digi-Reel® packaging is supplied in shorter tape segments on smaller reels, suitable for lower-volume production, prototype builds, or applications where partial reel quantities are acceptable. Both formats contain identical components; packaging format selection depends on production volume and assembly equipment compatibility.

Q: Are there any compliance differences between Littelfuse and Bourns substitute parts?

A: The Littelfuse 045104.6NRL carries CSA, PSE, and UL certifications. The Bourns SF-2410FP350T-2 and SF-2410HI350T-2 carry cUL and UL certifications. All parts are ROHS3 compliant and carry MSL 1 (Unlimited) moisture sensitivity ratings. The SF-2410HI350T-2 is marked as REACH Affected, which may require additional documentation in applications subject to REACH regulations. Verify certification requirements against your specific application and regional compliance standards before final part selection.

Q: What is the significance of the melting I²t values shown in the detailed specifications?

A: Melting I²t is a thermal characteristic that describes the fuse's energy absorption capacity before melting. While the listed substitute parts show variations in this parameter (ranging from 2.3 to 24.908), all parts are qualified for the same 4.6 A current rating and 50 A breaking capacity. These variations reflect differences in internal fuse element design between manufacturers and series designations but do not affect functional compatibility in applications designed for 4.6 A protection.

Q: Can I mix different substitute parts within the same circuit board assembly?

A: Yes. All listed parts meet identical electrical and mechanical specifications for the 4.6 A, 125 V AC/DC fast-blow protection function. Mixed sourcing from Littelfuse and Bourns manufacturers is permissible from an engineering compatibility standpoint. However, verify that your procurement, quality assurance, and supply chain processes support multi-source qualification before implementing mixed-source designs.