Littelfuse 045201.5MRSN Surface Mount Board Fuse Equivalent & Substitute Parts

Part Overview

The Littelfuse 045201.5MRSN is a 1.5 A, 125 V AC surface mount board fuse in the NANO²® 452 series. This fuse is designed for board-level overcurrent protection in electronic equipment and is actively manufactured. Equivalent and substitute parts are identified when component availability is limited, supply chain disruptions occur, or design flexibility is required while maintaining identical electrical and mechanical performance characteristics.

Substiute Parts

045201.5MRSN

Littelfuse Inc.In Stock: 1421045201.5MRSN Datasheet

Current PartRFQ

044901.5MR

Littelfuse Inc.In Stock: 2443044901.5MR Datasheet

Parametric EquivalentRFQ

045201.5MRL

Littelfuse Inc.In Stock: 40254045201.5MRL Datasheet

Parametric EquivalentRFQ

045401.5MR

Littelfuse Inc.In Stock: 4359045401.5MR Datasheet

Parametric EquivalentRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitute parts for the 045201.5MRSN are qualified based on the following criteria:

Mandatory Matching Parameters:

• Current Rating: 1.5 A
• Voltage Rating (AC): 125 V
• Response Time: Slow Blow
• Mounting Type: Surface Mount
• Package / Case: 2-SMD, Square End Block
• Physical Dimensions: 0.240" L x 0.106" W x 0.106" H (6.10mm x 2.69mm x 2.69mm)
• Breaking Capacity: 50 A @ Rated Voltage
• Operating Temperature Range: -55°C to 125°C
• RoHS Status: ROHS3 Compliant
• Moisture Sensitivity Level: 1 (Unlimited)

Allowed Variations:

• Voltage Rating (DC): May be specified or unspecified
• Series designation: Different NANO²® series (449, 452, 454)
• Packaging format: Tape & Reel (TR) or Cut Tape (CT) & Digi-Reel®
• Approval agencies: Variations in certification bodies (CSA, UR, cULus, PSE, UL)
• DC Cold Resistance: Minor variations within acceptable tolerance
• Melting I²t: Variations within the slow-blow fuse characteristic range

Parameter Comparison

Engineering Selection Recommendations

All four parts are active products manufactured by Littelfuse Inc. and meet the mandatory electrical and mechanical specifications for direct substitution in 1.5 A, 125 V AC surface mount board fuse applications.

045201.5MRL is the primary substitute, sharing identical series designation (NANO²® 452), DC cold resistance (0.093 Ω), and melting I²t (3.65) with the main part. This part adds DC voltage rating specification (125 V DC) and maintains Tape & Reel packaging. Inventory availability is significantly higher at 40,200 pieces.

045401.5MR is functionally equivalent with identical electrical characteristics (0.093 Ω DC cold resistance, 3.65 melting I²t) but is supplied in Cut Tape (CT) & Digi-Reel® format rather than standard Tape & Reel. This part is suitable for applications where alternative packaging formats are acceptable.

044901.5MR is a NANO²® 449 series alternative with specified DC voltage rating (125 V DC). This part exhibits higher DC cold resistance (0.1186 Ω) and higher melting I²t (4.7), which may affect response characteristics in specific circuit designs. Selection should be based on circuit requirements for these parameters.

All substitute parts maintain identical physical dimensions, breaking capacity, operating temperature range, RoHS compliance, and moisture sensitivity level. Certification differences reflect regional approval variations and do not affect functional equivalence.

Frequently Asked Questions (FAQ)

Q: Can 045201.5MRL be used as a direct replacement for 045201.5MRSN?

A: Yes. Both parts are NANO²® 452 series fuses with identical current rating (1.5 A), AC voltage rating (125 V), DC cold resistance (0.093 Ω), melting I²t (3.65), physical dimensions, and breaking capacity. The primary difference is packaging format (Tape & Reel for both) and the addition of DC voltage rating specification on the MRL variant.

Q: What is the significance of the DC cold resistance difference between 044901.5MR (0.1186 Ω) and the other substitutes (0.093 Ω)?

A: DC cold resistance affects the voltage drop across the fuse during normal operation. The 044901.5MR exhibits approximately 28% higher resistance, which may result in increased heat dissipation and voltage drop in the circuit. Selection depends on circuit design tolerance for these parameters.

Q: Are there packaging format restrictions for substitution?

A: The main part (045201.5MRSN) and substitutes 044901.5MR and 045201.5MRL are supplied in Tape & Reel (TR) format. Part 045401.5MR is supplied in Cut Tape (CT) & Digi-Reel® format. Packaging format selection depends on assembly equipment compatibility and procurement requirements, not electrical performance.

Q: Do certification differences affect substitution eligibility?

A: No. All parts are ROHS3 compliant and meet regional safety standards. Certification variations (CSA, UR, cULus, PSE, UL) reflect different geographic approval pathways and do not affect functional equivalence or electrical performance.

Q: Which substitute part should be selected for maximum inventory availability?

A: Part 045201.5MRL offers the highest inventory level at 40,200 pieces and maintains identical electrical characteristics to the main part, making it the optimal choice for supply chain continuity.