Littelfuse 045101.5MR Surface Mount Board Mount Fuse Equivalent & Substitute Parts

Part Overview

The Littelfuse 045101.5MR is a 1.5 A, 125 V AC/DC surface mount board mount fuse in the NANO²® 451 series. This part is classified as obsolete, making identification of active equivalent and substitute components essential for ongoing design support and procurement. The part operates across a temperature range of -55°C to 125°C with fast-blow response characteristics and is housed in a 2-SMD square end block package measuring 6.10mm × 2.69mm × 2.69mm.

Key Parameters

Parameter	Value
Current Rating	1.5 A
Voltage Rating (AC)	125 V
Voltage Rating (DC)	125 V
Response Time	Fast Blow
Mounting Type	Surface Mount
Fuse Type	Board Mount (Cartridge Style Excluded)
Package / Case	2-SMD, Square End Block
Breaking Capacity @ Rated Voltage	50 A
Operating Temperature Range	-55°C to 125°C
Size / Dimension	0.240" L × 0.106" W × 0.106" H (6.10mm × 2.69mm × 2.69mm)
Approval Agencies	CSA, PSE, UL

Substitute Part Grouping Explanation

Substitution of the 045101.5MR is determined by strict equivalence across the following critical parameters: current rating (1.5 A), AC and DC voltage ratings (125 V each), response time (fast blow), mounting type (surface mount), fuse type (board mount, cartridge style excluded), package configuration (2-SMD square end block), breaking capacity (50 A), and operating temperature range (-55°C to 125°C).

The substitute parts are grouped into two categories:

Littelfuse NANO²® Series Equivalents: Parts 044801.5MR, 045101.5MRL, 045101.5NRL, 045301.5MR, and 045301.5NR maintain identical electrical specifications and physical dimensions. These parts differ primarily in series designation (NANO²® 448 or 453), product status (active versus obsolete), packaging format (cut tape, digi-reel, or tape & reel), and RoHS compliance status.

Bourns SingleFuse™ Series Equivalents: Parts SF-2410FP150T-2 and SF-2410HI150T-2 meet the same electrical and mechanical requirements but originate from a different manufacturer. These parts exhibit minor dimensional variations (0.102" width and height versus 0.106") and different melting I²t characteristics, yet maintain functional equivalence within the specified parameters.

Parameter Comparison

Part Number	Manufacturer	Series	Current Rating (A)	Voltage AC/DC (V)	Response Time	Breaking Capacity (A)	Package	Size (mm)	Product Status	RoHS Status
045101.5MR	Littelfuse	NANO²® 451	1.5	125/125	Fast Blow	50	2-SMD, Square End Block	6.10 × 2.69 × 2.69	Obsolete	Non-compliant
044801.5MR	Littelfuse	NANO²® 448	1.5	125/125	Fast Blow	50	2-SMD, Square End Block	6.10 × 2.69 × 2.69	Active	ROHS3 Compliant
045101.5MRL	Littelfuse	NANO²® 451	1.5	125/125	Fast Blow	50	2-SMD, Square End Block	6.10 × 2.69 × 2.69	Active	ROHS3 Compliant
045101.5NRL	Littelfuse	NANO²® 451	1.5	125/125	Fast Blow	50	2-SMD, Square End Block	6.10 × 2.69 × 2.69	Active	ROHS3 Compliant
045301.5MR	Littelfuse	NANO²® 453	1.5	125/125	Fast Blow	50	2-SMD, Square End Block	6.10 × 2.69 × 2.69	Active	ROHS3 Compliant
045301.5NR	Littelfuse	NANO²® 453	1.5	125/125	Fast Blow	50	2-SMD, Square End Block	6.10 × 2.69 × 2.69	Active	ROHS3 Compliant
SF-2410FP150T-2	Bourns	SingleFuse™ SF-2410FP-T	1.5	125/125	Fast Blow	50	2-SMD, Square End Block	6.10 × 2.59 × 2.59	Active	ROHS3 Compliant
SF-2410HI150T-2	Bourns	SingleFuse™ SF-2410HI-T	1.5	125/125	Fast Blow	50	2-SMD, Square End Block	6.10 × 2.59 × 2.59	Active	ROHS3 Compliant

Engineering Selection Recommendations

For direct replacement with identical specifications and active product status: Select 045101.5MRL or 045101.5NRL. Both parts maintain the NANO²® 451 series designation, identical electrical and mechanical parameters, and active product status. The choice between these two depends on packaging requirements: 045101.5MRL is available in cut tape and digi-reel format, while 045101.5NRL is supplied in tape & reel format.

For alternative Littelfuse NANO²® series options: Parts 044801.5MR, 045301.5MR, and 045301.5NR provide active alternatives with full RoHS3 compliance. These parts maintain electrical equivalence and identical physical dimensions. Selection among these options should be based on packaging availability and inventory requirements.

For cross-manufacturer substitution: Bourns SingleFuse™ parts SF-2410FP150T-2 and SF-2410HI150T-2 are functionally equivalent alternatives. Both are active products with RoHS3 compliance and UL/cUL certification. Minor dimensional differences (0.102" versus 0.106" width and height) are within typical PCB layout tolerances for surface mount applications. SF-2410HI150T-2 carries REACH-affected status, requiring verification against supply chain requirements.

Compliance considerations: All substitute parts except the original 045101.5MR carry RoHS3 compliance certification. All recommended substitutes maintain CSA, PSE, and UL approval agencies or equivalent (cUL, UL for Bourns parts).

Frequently Asked Questions (FAQ)

Q: Can I use 045101.5MRL as a direct replacement for the obsolete 045101.5MR?

A: Yes. The 045101.5MRL is electrically and mechanically identical to the 045101.5MR, with the primary difference being active product status and RoHS3 compliance. The only consideration is packaging format: 045101.5MRL is supplied in cut tape and digi-reel, while the original may have been supplied differently.

Q: What is the difference between the Littelfuse NANO²® 451 and 453 series fuses?

A: Both series maintain identical electrical specifications (1.5 A, 125 V AC/DC, fast blow) and physical dimensions for the 1.5 A rating. The series designation reflects internal design iterations within the Littelfuse product line. Selection between them should be based on availability and packaging format preference.

Q: Are Bourns SingleFuse™ parts truly equivalent to Littelfuse NANO²® fuses?

A: Bourns SF-2410FP150T-2 and SF-2410HI150T-2 meet all specified electrical and mechanical requirements for substitution. Minor dimensional variations (0.102" versus 0.106" in width and height) are within standard PCB layout tolerances. Both carry UL/cUL certification and RoHS3 compliance. Verification of melting I²t characteristics against circuit protection requirements is recommended for critical applications.

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

A: Littelfuse NANO²® equivalents are available in three formats: cut tape (CT) & digi-reel (045101.5MRL, 044801.5MR), and tape & reel (TR) (045101.5NRL, 045301.5MR, 045301.5NR). Bourns SingleFuse™ parts are supplied in tape & reel format only. Selection should align with assembly line equipment capabilities.

Q: Do all substitute parts carry the same regulatory approvals as the original 045101.5MR?

A: Littelfuse NANO²® substitutes maintain CSA, PSE, and UL approvals identical to the original. Bourns SingleFuse™ parts carry cUL and UL certifications, which provide equivalent regulatory coverage for North American and international markets. Verification against specific regional requirements is recommended.

Q: Is there a difference in DC cold resistance between substitute options?

A: Yes. DC cold resistance varies across the substitute parts: Littelfuse NANO²® 451 and 453 series parts measure 0.063 Ohms, while 044801.5MR measures 0.06514 Ohms. Bourns SF-2410FP150T-2 measures 0.114 Ohms, and SF-2410HI150T-2 measures 0.057 Ohms. These variations may impact circuit behavior in low-resistance applications and should be evaluated against circuit design specifications.

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