Littelfuse 0452003.MR Surface Mount Board Mount Fuse Equivalent & Substitute Parts

Part Overview

The Littelfuse 0452003.MR is a 3 A, 125 V AC/DC surface mount board mount fuse in the NANO²® 452 series, featuring a 2-SMD square end block package. This part is classified as obsolete. Due to its obsolete status, equivalent substitute parts from active product lines are available to maintain design continuity and ensure ongoing component availability for production and repair applications.

Key Parameters

Parameter	Value
Current Rating	3 A
Voltage Rating (AC)	125 V
Voltage Rating (DC)	125 V
Response Time	Slow Blow
Mounting Type	Surface Mount
Fuse Type	Board Mount (Cartridge Style Excluded)
Package / Case	2-SMD, Square End Block
Size / Dimension	0.240" L x 0.106" W x 0.106" H (6.10mm x 2.69mm x 2.69mm)
Breaking Capacity @ Rated Voltage	50 A
Operating Temperature Range	-55°C ~ 125°C

Substitute Part Grouping Explanation

Substitution of the 0452003.MR is determined by strict equivalence across the following critical parameters:

Current Rating: 3 A (exact match required)
Voltage Rating: 125 V AC and 125 V DC (exact match required)
Response Time: Slow 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)

All substitute parts listed below meet these criteria and are therefore electrically and mechanically interchangeable with the 0452003.MR. Differences in packaging format (Cut Tape & Digi-Reel® versus Tape & Reel) and product status do not affect functional equivalence.

Parameter Comparison

Part Number	Manufacturer	Series	Current Rating	Voltage AC/DC	Response Time	Package	Dimensions (mm)	Breaking Capacity	DC Cold Resistance (Ω)	Product Status	Packaging Format
0452003.MR	Littelfuse Inc.	NANO²® 452	3 A	125 V / 125 V	Slow Blow	2-SMD, Square End Block	6.10 x 2.69 x 2.69	50 A	0.034	Obsolete	-
0452003.MRL	Littelfuse Inc.	NANO²® 452	3 A	125 V / 125 V	Slow Blow	2-SMD, Square End Block	6.10 x 2.69 x 2.69	50 A	0.034	Active	Cut Tape & Digi-Reel®
0454003.MR	Littelfuse Inc.	NANO²® 454	3 A	125 V / 125 V	Slow Blow	2-SMD, Square End Block	6.10 x 2.69 x 2.69	50 A	0.034	Active	Cut Tape & Digi-Reel®
0454003.NR	Littelfuse Inc.	NANO²® 454	3 A	125 V / 125 V	Slow Blow	2-SMD, Square End Block	6.10 x 2.69 x 2.69	50 A	0.034	Active	Tape & Reel
0449003.MR	Littelfuse Inc.	NANO²® 449	3 A	125 V / 125 V	Slow Blow	2-SMD, Square End Block	6.10 x 2.69 x 2.69	50 A	0.0352	Active	Tape & Reel

Engineering Selection Recommendations

All substitute parts are active products from Littelfuse Inc. and provide direct functional replacement for the obsolete 0452003.MR.

0452003.MRL is the primary substitute, maintaining identical electrical characteristics and the same NANO²® 452 series designation. It differs only in packaging format (Cut Tape & Digi-Reel® versus the original packaging) and holds active product status with RoHS3 compliance and REACH unaffected status.

0454003.MR and 0454003.NR are functionally equivalent alternatives from the NANO²® 454 series. Both maintain identical electrical specifications and physical dimensions. 0454003.MR is supplied in Cut Tape & Digi-Reel® format, while 0454003.NR is supplied in Tape & Reel format. Both are active products with RoHS3 compliance.

0449003.MR is a functionally equivalent alternative from the NANO²® 449 series. It maintains identical electrical specifications and physical dimensions. The DC cold resistance is 0.0352 Ω compared to 0.034 Ω in the original part, which remains within acceptable tolerance for this component class. This part is supplied in Tape & Reel format and is an active product with RoHS3 compliance and REACH unaffected status.

Selection among these substitutes should be based on packaging format requirements and inventory availability rather than electrical performance, as all parts are electrically and mechanically interchangeable.

Frequently Asked Questions (FAQ)

Q: Can 0452003.MRL be used as a direct replacement for 0452003.MR?

A: Yes. The 0452003.MRL is electrically and mechanically identical to the 0452003.MR. The only difference is packaging format (Cut Tape & Digi-Reel® versus the original packaging) and product status (active versus obsolete). Both parts share the same NANO²® 452 series designation and identical electrical specifications.

Q: What is the difference between the NANO²® 452, 454, and 449 series substitutes?

A: All three series maintain identical electrical ratings (3 A, 125 V AC/DC, slow blow response) and physical dimensions (6.10mm x 2.69mm x 2.69mm). The series designation reflects internal design evolution within Littelfuse's product line. The 0449003.MR exhibits a DC cold resistance of 0.0352 Ω versus 0.034 Ω in the 452 and 454 series, a negligible difference for board mount fuse applications.

Q: Does packaging format affect electrical performance?

A: No. Packaging format (Cut Tape & Digi-Reel®, Tape & Reel, or bulk) does not affect the electrical or mechanical performance of the fuse. Selection should be based on assembly equipment compatibility and procurement requirements.

Q: Are all substitute parts RoHS compliant?

A: The original 0452003.MR is RoHS non-compliant. All substitute parts (0452003.MRL, 0454003.MR, 0454003.NR, and 0449003.MR) are RoHS3 compliant, with the exception of 0449003.MR and 0454003.NR which carry REACH unaffected status.

Q: Can I mix different substitute part numbers in the same production run?

A: Yes. All substitute parts are electrically and mechanically interchangeable. However, for traceability and quality control purposes, it is recommended to maintain consistent part number usage within a single production batch where possible.

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