Littelfuse 045101.6MRSN Surface Mount Board Fuse Equivalent & Substitute Parts

Part Overview

The Littelfuse 045101.6MRSN is a 1.6 A 125 V AC surface mount board fuse in the NANO²® 451 series, designed for fast-blow protection in compact 2-SMD, square end block packaging. This part is currently active in production with 1021 pieces in stock. Equivalent and substitute parts are identified when design requirements necessitate alternative sourcing, inventory optimization, or compatibility with specific manufacturing processes while maintaining identical electrical and mechanical performance parameters.

Key Parameters

Parameter	Value
Current Rating	1.6 A
Voltage Rating (AC)	125 V
Response Time	Fast Blow
Mounting Type	Surface Mount
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
RoHS Status	ROHS3 Compliant
Moisture Sensitivity Level (MSL)	1 (Unlimited)

Substitute Part Grouping Explanation

Substitute parts for the 045101.6MRSN are qualified based on strict equivalence across the following critical parameters: current rating (1.6 A), AC voltage rating (125 V), response time (fast blow), mounting type (surface mount), package configuration (2-SMD, square end block), physical dimensions (0.240" L x 0.106" W x 0.106" H), breaking capacity (50 A), operating temperature range (-55°C ~ 125°C), and compliance certifications (CSA, UL, PSE). All substitute parts listed maintain these core electrical and mechanical specifications. Differences in DC voltage rating capability, melting I²t values, DC cold resistance, and series designation (NANO²® 448, 451, 453) do not affect substitution eligibility when AC-only operation is specified. Packaging format (Tape & Reel) remains consistent across all qualified substitutes.

Parameter Comparison

Parameter	045101.6MRSN (Main)	044801.6MR	045101.6MRL	045301.6MR
Manufacturer	Littelfuse Inc.	Littelfuse Inc.	Littelfuse Inc.	Littelfuse Inc.
Current Rating (Amps)	1.6 A	1.6 A	1.6 A	1.6 A
Voltage Rating - AC	125 V	125 V	125 V	125 V
Voltage Rating - DC	Not specified	125 V	125 V	125 V
Response Time	Fast Blow	Fast Blow	Fast Blow	Fast Blow
Mounting Type	Surface Mount	Surface Mount	Surface Mount	Surface Mount
Package / Case	2-SMD, Square End Block	2-SMD, Square End Block	2-SMD, Square End Block	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)	0.240" L x 0.106" W x 0.106" H (6.10mm x 2.69mm x 2.69mm)	0.240" L x 0.106" W x 0.106" H (6.10mm x 2.69mm x 2.69mm)	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	50 A	50 A	50 A
Melting I²t	1.06	1.122	1.06	1.06
DC Cold Resistance (Ohms)	0.058	0.06261	0.058	0.058
Operating Temperature	-55°C ~ 125°C	-55°C ~ 125°C	-55°C ~ 125°C	-55°C ~ 125°C
Approval Agency	CSA, UR	CSA, UL, PSE	CSA, PSE, UL	CSA, PSE, UL
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Moisture Sensitivity Level (MSL)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)
Series	NANO²® 451	NANO²® 448	NANO²® 451	NANO²® 453
Product Status	Active	Active	Active	Active
Inventory (Pcs)	1021	1439	65200	1488

Engineering Selection Recommendations

All four parts (045101.6MRSN, 044801.6MR, 045101.6MRL, 045301.6MR) maintain active product status and full ROHS3 compliance. Selection between these equivalents is determined by certification requirements and DC voltage capability needs. The 045101.6MRSN carries CSA and UR approvals. The 044801.6MR, 045101.6MRL, and 045301.6MR each carry CSA, UL, and PSE certifications, providing broader regulatory coverage. For applications requiring DC voltage protection, 044801.6MR, 045101.6MRL, and 045301.6MR are rated for 125 V DC in addition to 125 V AC, whereas 045101.6MRSN is specified for AC only. The 045101.6MRL offers the highest inventory availability (65200 pieces), supporting supply chain continuity. Melting I²t and DC cold resistance variations are minor and do not affect AC-only circuit protection performance.

Frequently Asked Questions (FAQ)

Q: Can 045101.6MRL be used as a direct replacement for 045101.6MRSN?

A: Yes. Both parts share identical current rating (1.6 A), AC voltage rating (125 V), response time (fast blow), package configuration (2-SMD, square end block), physical dimensions, breaking capacity (50 A), operating temperature range (-55°C ~ 125°C), and RoHS3 compliance. The 045101.6MRL additionally supports 125 V DC operation and carries UL and PSE certifications alongside CSA approval.

Q: What is the difference between 045101.6MRSN and 044801.6MR?

A: Both parts are electrically equivalent for AC 125 V, 1.6 A fast-blow protection with identical package and dimensions. The 044801.6MR belongs to the NANO²® 448 series versus the 451 series for the main part, carries UL and PSE certifications in addition to CSA, supports 125 V DC operation, and has a slightly higher melting I²t value (1.122 versus 1.06) and DC cold resistance (0.06261 versus 0.058 Ohms).

Q: Are all substitute parts available in Tape & Reel packaging?

A: Yes. All listed substitute parts (044801.6MR, 045101.6MRL, 045301.6MR) are supplied in Tape & Reel (TR) packaging, matching the packaging format of the 045101.6MRSN.

Q: Which substitute part has the best inventory availability?

A: The 045101.6MRL has the highest inventory level at 65200 pieces in stock, compared to 1021 pieces for the main part, 1439 pieces for 044801.6MR, and 1488 pieces for 045301.6MR.

Q: Do all parts meet the same regulatory certifications?

A: The 045101.6MRSN carries CSA and UR approvals. The substitute parts 044801.6MR, 045101.6MRL, and 045301.6MR each carry CSA, UL, and PSE certifications. For applications requiring UL or PSE compliance, the substitute parts provide broader certification coverage.

Q: Can these parts be used in DC circuits?

A: The 045101.6MRSN is specified for AC 125 V operation only. The substitute parts 044801.6MR, 045101.6MRL, and 045301.6MR are rated for both AC 125 V and DC 125 V, enabling use in DC or mixed AC/DC applications.

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