Littelfuse 0452.500MR Surface Mount Fuse Equivalent & Substitute Parts

Part Overview

The Littelfuse 0452.500MR is a 500 mA, 125 V AC/DC surface mount board fuse in the NANO²® 452 series with a 2-SMD square end block package. This part is classified as obsolete, making equivalent substitute parts necessary for new designs and ongoing production requirements. The substitute parts listed maintain identical electrical ratings and mechanical compatibility while offering active product status and improved compliance certifications.

Key Parameters

Parameter	Value
Current Rating	500 mA
Voltage Rating (AC)	125 V
Voltage Rating (DC)	125 V
Response Time	Slow Blow
Package / Case	2-SMD, Square End Block
Mounting Type	Surface Mount
Breaking Capacity @ Rated Voltage	50 A
Operating Temperature Range	-55°C to 125°C
Size / Dimension	0.240" L x 0.106" W x 0.106" H (6.10mm x 2.69mm x 2.69mm)

Substitute Part Grouping Explanation

Substitution eligibility for the 0452.500MR is determined by the following mandatory parameters:

Current Rating: 500 mA (exact match required)
Voltage Rating: 125 V AC and 125 V DC (exact match required)
Response Time: Slow Blow (exact match required)
Package / Case: 2-SMD, Square End Block (exact match required)
Mounting Type: Surface Mount (exact match required)
Breaking Capacity: 50 A @ Rated Voltage (exact match required)
Operating Temperature Range: -55°C to 125°C (exact match required)
Physical Dimensions: 0.240" L x 0.106" W x 0.106" H (exact match required)

All substitute parts listed meet these criteria. Variations in packaging format (tape & reel, cut tape, digi-reel), series designation (NANO²® 449, 452, 454), and compliance certifications do not affect electrical or mechanical interchangeability.

Parameter Comparison

Part Number	Manufacturer	Series	Current Rating	Voltage AC/DC	Response Time	Package	Breaking Capacity	Melting I²t	DC Cold Resistance	Operating Temp	Product Status	RoHS Status
0452.500MR	Littelfuse Inc.	NANO²® 452	500 mA	125 V / 125 V	Slow Blow	2-SMD, Square End Block	50 A	0.24	0.7 Ω	-55°C ~ 125°C	Obsolete	RoHS non-compliant
0449.500MR	Littelfuse Inc.	NANO²® 449	500 mA	125 V / 125 V	Slow Blow	2-SMD, Square End Block	50 A	0.258	0.7633 Ω	-55°C ~ 125°C	Active	ROHS3 Compliant
0452.500MRL	Littelfuse Inc.	NANO²® 452	500 mA	125 V / 125 V	Slow Blow	2-SMD, Square End Block	50 A	0.24	0.7 Ω	-55°C ~ 125°C	Active	ROHS3 Compliant
0452.500NRL	Littelfuse Inc.	NANO²® 452	500 mA	125 V / 125 V	Slow Blow	2-SMD, Square End Block	50 A	0.024	0.7 Ω	-55°C ~ 125°C	Active	ROHS3 Compliant
0454.500MR	Littelfuse Inc.	NANO²® 454	500 mA	125 V / 125 V	Slow Blow	2-SMD, Square End Block	50 A	0.24	0.7 Ω	-55°C ~ 125°C	Active	ROHS3 Compliant
0454.500NR	Littelfuse Inc.	NANO²® 454	500 mA	125 V / 125 V	Slow Blow	2-SMD, Square End Block	50 A	0.24	0.7 Ω	-55°C ~ 125°C	Active	ROHS3 Compliant

Engineering Selection Recommendations

All substitute parts are electrically and mechanically equivalent to the 0452.500MR. Selection should be based on the following factors:

Product Status: The 0452.500MR is obsolete. All substitute parts listed carry active product status, ensuring long-term availability and continued manufacturer support.

Compliance Certifications: The 0452.500MR is RoHS non-compliant. All substitute parts are ROHS3 compliant, meeting current environmental and regulatory requirements for new designs and production.

Series Selection: The 0452.500MRL is the direct series equivalent, maintaining the NANO²® 452 designation with identical electrical characteristics and active status. The 0449.500MR (NANO²® 449 series) and 0454.500MR / 0454.500NR (NANO²® 454 series) are cross-series alternatives with equivalent performance.

Packaging Considerations: The 0452.500MRL is available in Cut Tape (CT) & Digi-Reel® format with the highest inventory (150,200 pcs), providing optimal supply chain availability. Tape & Reel (TR) packaging options are available through 0449.500MR, 0452.500NRL, 0454.500MR, and 0454.500NR.

Frequently Asked Questions (FAQ)

Q: Can I directly replace the 0452.500MR with any of the listed substitute parts?

A: Yes. All substitute parts maintain identical current rating (500 mA), voltage rating (125 V AC/DC), response time (Slow Blow), package type (2-SMD, Square End Block), and physical dimensions. Direct PCB-level substitution is supported without design modification.

Q: What is the difference between the 0452.500MRL and 0452.500MR?

A: The 0452.500MRL is the active production equivalent of the obsolete 0452.500MR. Both are NANO²® 452 series fuses with identical electrical specifications (500 mA, 125 V AC/DC, 0.24 Melting I²t, 0.7 Ω DC cold resistance). The primary difference is product status: 0452.500MR is obsolete, while 0452.500MRL is active and RoHS3 compliant.

Q: Why do some substitute parts have different Melting I²t values?

A: Melting I²t is a secondary thermal characteristic that does not affect primary substitution eligibility. All parts maintain the same current rating, voltage rating, and response time classification. The 0452.500NRL variant has a lower Melting I²t value (0.024 vs. 0.24), but this does not impact electrical interchangeability for standard circuit protection applications.

Q: What packaging formats are available for these substitute parts?

A: The 0452.500MRL is supplied in Cut Tape (CT) & Digi-Reel® format. The 0449.500MR, 0452.500NRL, 0454.500MR, and 0454.500NR are supplied in Tape & Reel (TR) format. All packaging formats are compatible with standard SMD assembly equipment.

Q: Are all substitute parts RoHS compliant?

A: Yes. All substitute parts listed are ROHS3 compliant. The original 0452.500MR is RoHS non-compliant, making substitution necessary for designs requiring RoHS certification.

Q: Which substitute part offers the best supply chain availability?

A: The 0452.500MRL offers the highest inventory level (150,200 pcs new original in stock), providing optimal availability for production requirements.

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