Littelfuse 0451.200MR Surface Mount Fuse Equivalent & Substitute Parts

Part Overview

The Littelfuse 0451.200MR is a 200 mA, 125 V AC/DC surface mount board fuse in the NANO²® 451 series with a 2-SMD square end block package. This part is classified as obsolete. Equivalent and substitute parts are available from Littelfuse's active product lines and from alternative manufacturers, providing direct functional replacements with identical electrical ratings and mechanical compatibility.

Key Parameters

Parameter	Value
Current Rating	200 mA
Voltage Rating (AC)	125 V
Voltage Rating (DC)	125 V
Response Time	Fast Blow
Mounting Type	Surface Mount
Package / Case	2-SMD, Square End Block
Breaking Capacity @ Rated Voltage	50 A
Operating Temperature Range	-55°C ~ 125°C
Size / Dimension	0.240" L x 0.106" W x 0.106" H (6.10mm x 2.69mm x 2.69mm)
Approval Agency	CSA, UL

Substitute Part Grouping Explanation

Substitution for the 0451.200MR is determined by strict equivalence across the following parameters:

Current Rating: 200 mA (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: 50 A @ rated voltage (exact match required)
Operating Temperature: -55°C ~ 125°C (exact match required)

All substitute parts listed meet these criteria. Differences in melting I²t, DC cold resistance, and RoHS compliance status are noted but do not preclude substitution when electrical and mechanical parameters are identical.

Parameter Comparison

Part Number	Manufacturer	Series	Current Rating	Voltage AC/DC	Response Time	Package	Breaking Capacity	Operating Temp	Product Status	RoHS Status
0451.200MR	Littelfuse Inc.	NANO²® 451	200 mA	125 V / 125 V	Fast Blow	2-SMD, Square End Block	50 A	-55°C ~ 125°C	Obsolete	RoHS non-compliant
0451.200NRL	Littelfuse Inc.	NANO²® 451	200 mA	125 V / 125 V	Fast Blow	2-SMD, Square End Block	50 A	-55°C ~ 125°C	Active	ROHS3 Compliant
0448.200MR	Littelfuse Inc.	NANO²® 448	200 mA	125 V / 125 V	Fast Blow	2-SMD, Square End Block	50 A	-55°C ~ 125°C	Active	ROHS3 Compliant
0451.200MRL	Littelfuse Inc.	NANO²® 451	200 mA	125 V / 125 V	Fast Blow	2-SMD, Square End Block	50 A	-55°C ~ 125°C	Active	ROHS3 Compliant
0453.200MR	Littelfuse Inc.	NANO²® 453	200 mA	125 V / 125 V	Fast Blow	2-SMD, Square End Block	50 A	-55°C ~ 125°C	Active	ROHS3 Compliant
0453.200NR	Littelfuse Inc.	NANO²® 453	200 mA	125 V / 125 V	Fast Blow	2-SMD, Square End Block	50 A	-55°C ~ 125°C	Active	ROHS3 Compliant
SF-2410FP020T-2	Bourns Inc.	SinglFuse™ SF-2410FP-T	200 mA	125 V / 125 V	Fast Blow	2-SMD, Square End Block	50 A	-55°C ~ 125°C	Active	ROHS3 Compliant

Engineering Selection Recommendations

For new designs and production transitions, select from active product status parts. The Littelfuse 0451.200NRL and 0451.200MRL are direct series equivalents with ROHS3 compliance and active manufacturing status. The Littelfuse 0448.200MR and 0453.200MR series parts provide parametric equivalence within the Littelfuse NANO²® product family, all with active status and ROHS3 compliance. The Bourns SF-2410FP020T-2 offers cross-manufacturer equivalence with identical electrical and mechanical specifications and active product status.

All substitute parts carry CSA and UL approvals (or cUL and UL for the Bourns part), meeting the same regulatory requirements as the original 0451.200MR.

Frequently Asked Questions (FAQ)

Q: Can the 0451.200NRL directly replace the 0451.200MR? A: Yes. The 0451.200NRL is the active product equivalent within the same NANO²® 451 series. It maintains identical electrical ratings (200 mA, 125 V AC/DC, fast blow response), mechanical dimensions, and package configuration. The primary difference is product status (active vs. obsolete) and RoHS compliance (ROHS3 vs. non-compliant).

Q: What is the difference between the 0451.200MR and 0448.200MR? A: Both parts share identical electrical ratings and mechanical specifications. The primary difference is the series designation (NANO²® 451 vs. NANO²® 448). The 0448.200MR is from an active product line with ROHS3 compliance and higher inventory availability.

Q: Are Littelfuse and Bourns fuses interchangeable? A: The Bourns SF-2410FP020T-2 meets all electrical and mechanical parameters of the 0451.200MR. Both are 200 mA, 125 V AC/DC, fast blow, surface mount fuses in identical 2-SMD square end block packages with 50 A breaking capacity. Cross-manufacturer substitution is electrically and mechanically valid.

Q: Does packaging format affect substitution? A: All listed substitutes are supplied in Tape & Reel (TR) format or equivalent surface mount packaging. The 0451.200MR was supplied in bulk format. Tape & Reel packaging is standard for surface mount assembly and does not affect electrical or mechanical compatibility.

Q: Why is RoHS compliance status listed as different? A: The original 0451.200MR is RoHS non-compliant. All active substitute parts (0451.200NRL, 0448.200MR, 0451.200MRL, 0453.200MR, 0453.200NR, and SF-2410FP020T-2) are ROHS3 compliant, meeting current environmental regulations for new production.

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