SST 5-5K Surface Mount Board Mount Fuse Equivalent & Substitute Parts

Part Overview

The SST 5-5K is a 5 A, 125 V AC/DC surface mount board mount fuse manufactured by Bel Fuse Inc. in 2-SMD, Square End Block package configuration. This part is classified as Obsolete, which necessitates identification of active equivalent and substitute components for ongoing design support and procurement continuity. Equivalent parts maintain identical electrical and mechanical specifications, while substitute parts satisfy the same functional requirements within allowable parameter tolerances for this fuse category.

Key Parameters

Parameter	Value
Current Rating	5 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 0.100" W x 0.100" H (6.10mm x 2.54mm x 2.54mm)
Operating Temperature	-55°C ~ 125°C
RoHS Status	ROHS3 Compliant
Moisture Sensitivity Level	1 (Unlimited)

Substitute Part Grouping Explanation

Substitution eligibility for the SST 5-5K is determined by strict equivalence across the following critical parameters:

Mandatory Matching Parameters:

Current Rating: 5 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 0.100" W x 0.100" H (6.10mm x 2.54mm x 2.54mm)
Operating Temperature Range: -55°C ~ 125°C
RoHS Status: ROHS3 Compliant
Moisture Sensitivity Level: 1 (Unlimited)

Allowable Variation Parameters:

Breaking Capacity @ Rated Voltage: 50 A minimum
Melting I²t: 24 to 59.59 (within design tolerance)
DC Cold Resistance: 0.0136 to 0.026 Ohms
Approval Agency: Subset of or equivalent to original certifications

All substitute parts listed maintain identical electrical performance characteristics and mechanical compatibility with the SST 5-5K within the specified parameter ranges.

Parameter Comparison

Part Number	Manufacturer	Series	Current Rating (A)	Voltage AC (V)	Voltage DC (V)	Response Time	Breaking Capacity @ Rated Voltage	Melting I²t	DC Cold Resistance (Ohms)	Product Status	Packaging
SST 5-5K	Bel Fuse Inc.	SST	5	125	125	Slow Blow	50A	38	0.017	Obsolete	Cut Tape (CT) & Digi-Reel®
0680L5000-01	Bel Fuse	0680L	5	125	125	Slow Blow	50A AC, 100A DC	37	0.019	Active	Tape & Reel (TR)
0680L5000-05	Bel Fuse Inc.	0680L	5	125	125	Slow Blow	50A AC, 100A DC	37	0.019	Active	Cut Tape (CT) & Digi-Reel®
0680L5000-11	Bel Fuse	0680L	5	125	125	Slow Blow	50A AC, 100A DC	37	0.019	Active	Tape & Reel (TR)
0680L5000-15	Bel Fuse	0680L	5	125	125	Slow Blow	50A AC, 100A DC	37	0.019	Active	Tape & Reel (TR)
0680L5000-21	Bel Fuse	0680L	5	125	125	Slow Blow	50A AC, 100A DC	37	0.019	Active	Tape & Reel (TR)
0680L5000-25	Bel Fuse Inc.	0680L	5	125	125	Slow Blow	50A AC, 100A DC	37	0.019	Active	Tape & Reel (TR)
0680H5000-01	Bel Fuse Inc.	0680H	5	125	125	Slow Blow	100A AC, 500A DC	24	0.026	Active	Tape & Reel (TR)
0680H5000-05	Bel Fuse Inc.	0680H	5	125	125	Slow Blow	100A AC, 500A DC	24	0.019	Active	Tape & Reel (TR)
0449005.MR	Littelfuse	NANO²® 449	5	125	125	Slow Blow	50A	59.59	0.0171	Active	Cut Tape (CT) & Digi-Reel®
0452005.MRL	Littelfuse Inc.	NANO²® 452	5	125	125	Slow Blow	50A	53.72	0.0136	Active	Cut Tape (CT) & Digi-Reel®

Engineering Selection Recommendations

Bel Fuse 0680L Series (0680L5000-01, 0680L5000-05, 0680L5000-11, 0680L5000-15, 0680L5000-21, 0680L5000-25): These parts are direct functional equivalents to the SST 5-5K with Active product status. All variants maintain identical electrical ratings and mechanical dimensions. The 0680L series offers enhanced DC breaking capacity (100A DC vs. 50A DC) and improved inventory availability. Selection among variants depends on packaging requirement: Cut Tape (CT) & Digi-Reel® for 0680L5000-05, or Tape & Reel (TR) for remaining variants. All carry AEC-Q200 and CE certifications.

Bel Fuse 0680H Series (0680H5000-01, 0680H5000-05): These parts provide parametric equivalence with superior breaking capacity (100A AC, 500A DC) and lower melting I²t (24 vs. 38). The 0680H series is suitable for applications requiring enhanced fault tolerance. Certification is limited to cURus. Both variants are available in Tape & Reel (TR) packaging.

Littelfuse NANO²® 449 (0449005.MR): This part maintains electrical equivalence with 50A breaking capacity and is available in Cut Tape (CT) & Digi-Reel® packaging. Melting I²t is 59.59, representing higher thermal mass. Certifications include cULus and PSE. Dimensional tolerance is 0.240" L x 0.106" W x 0.106" H, representing a 0.006" increase in width and height compared to the SST 5-5K.

Littelfuse NANO²® 452 (0452005.MRL): This part provides electrical equivalence with 50A breaking capacity and is available in Cut Tape (CT) & Digi-Reel® packaging. Melting I²t is 53.72. Certifications include CSA, PSE, and UR. Dimensional tolerance is 0.240" L x 0.106" W x 0.106" H, representing a 0.006" increase in width and height compared to the SST 5-5K.

Frequently Asked Questions (FAQ)

Q: Can I use 0680L5000 variants as direct replacements for SST 5-5K? A: Yes. The 0680L5000 series maintains identical electrical ratings (5 A, 125 V AC/DC), response time (Slow Blow), package type (2-SMD, Square End Block), and physical dimensions (0.240" L x 0.100" W x 0.100" H). All variants are Active products with established supply chains.

Q: What is the difference between 0680L and 0680H series? A: Both series maintain identical electrical ratings and dimensions. The 0680H series provides higher breaking capacity (100A AC, 500A DC vs. 50A AC, 100A DC) and lower melting I²t (24 vs. 37). Selection depends on application fault tolerance requirements.

Q: Can I substitute Littelfuse NANO²® parts for Bel Fuse parts? A: Littelfuse 0449005.MR and 0452005.MRL maintain electrical equivalence (5 A, 125 V AC/DC, Slow Blow response). However, dimensional tolerance increases to 0.106" width and height (vs. 0.100"). Verify PCB layout clearance before substitution. Certification profiles differ; confirm compliance requirements for your application.

Q: What packaging options are available? A: Cut Tape (CT) & Digi-Reel® packaging is available for SST 5-5K, 0680L5000-05, 0449005.MR, and 0452005.MRL. Tape & Reel (TR) packaging is available for 0680L5000-01, 0680L5000-11, 0680L5000-15, 0680L5000-21, 0680L5000-25, 0680H5000-01, and 0680H5000-05. Select based on assembly process requirements.

Q: Are all substitute parts RoHS3 compliant? A: Yes. All listed substitute parts maintain ROHS3 Compliant status and Moisture Sensitivity Level 1 (Unlimited), matching the SST 5-5K specifications.

Q: What certifications should I verify for my application? A: The SST 5-5K carries AEC-Q200, CE, CSA, and cULus certifications. The 0680L series carries AEC-Q200, CE, and cURus certifications. The 0680H series carries cURus certification only. Littelfuse parts carry cULus/PSE (0449005.MR) or CSA/PSE/UR (0452005.MRL) certifications. Confirm your application's certification requirements before selection.

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