SST 1.5/5K Surface Mount Board Fuse - Equivalent & Substitute Parts

Part Overview

The SST 1.5/5K is a 1.5 A, 125 V AC/DC surface mount board fuse manufactured by Bel Fuse Inc. in a 2-SMD, Square End Block package. This part is classified as obsolete, with 807 pieces currently in stock. Due to its obsolete status, identifying active equivalent and substitute parts is essential for ongoing design support, production continuity, and long-term component availability. Direct substitutes from the active 0680L series and parametric equivalents from the 0680H series and alternative manufacturers provide viable alternatives for new designs and production requirements.

Key Parameters

Parameter	Value
Current Rating	1.5 A
Voltage Rating (AC)	125 V
Voltage Rating (DC)	125 V
Response Time	Slow Blow
Mounting Type	Surface Mount
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 for the SST 1.5/5K is determined by strict equivalence in the following parameters:

Current Rating: 1.5 A (mandatory)
Voltage Rating: 125 V AC and 125 V DC (mandatory)
Response Time: Slow Blow (mandatory)
Mounting Type: Surface Mount (mandatory)
Package / Case: 2-SMD, Square End Block (mandatory)
Operating Temperature Range: -55°C ~ 125°C (mandatory)
RoHS Status: ROHS3 Compliant (mandatory)

Substitute parts are grouped into two categories:

Direct Substitutes (Active Status): Parts from the Bel Fuse 0680L series (0680L1500-11, 0680L1500-15, 0680L1500-21, 0680L1500-25, 0680L1500-01, 0680L1500-05) maintain identical electrical and mechanical specifications with active product status and enhanced availability.

Parametric Equivalents: Parts from the Bel Fuse 0680H series (0680H1500-01, 0680H1500-05) and Littelfuse NANO²® series (044901.5MR, 045201.5MRL) meet all mandatory parameters but differ in secondary characteristics such as breaking capacity, melting I²t, DC cold resistance, and approval agency certifications. These are suitable where the enhanced performance characteristics are acceptable or beneficial.

Parameter Comparison

Part Number	Manufacturer	Status	Current (A)	Voltage AC (V)	Voltage DC (V)	Response Time	Package	Size (mm)	Temp Range (°C)	Breaking Capacity AC (A)	Breaking Capacity DC (A)	Melting I²t	DC Cold Resistance (Ω)	Approvals
SST 1.5/5K	Bel Fuse Inc.	Obsolete	1.5	125	125	Slow Blow	2-SMD, Square End Block	6.10 x 2.54 x 2.54	-55 ~ 125	50	—	3	0.081	AEC-Q200, CE, CSA, cULus
0680L1500-11	Bel Fuse Inc.	Active	1.5	125	125	Slow Blow	2-SMD, Square End Block	6.10 x 2.54 x 2.54	-55 ~ 125	50	100	3.3	0.095	AEC-Q200, CE, cURus
0680L1500-15	Bel Fuse	Active	1.5	125	125	Slow Blow	2-SMD, Square End Block	6.10 x 2.54 x 2.54	-55 ~ 125	50	100	3.3	0.095	AEC-Q200, CE, cURus
0680L1500-21	Bel Fuse Inc.	Active	1.5	125	125	Slow Blow	2-SMD, Square End Block	6.10 x 2.54 x 2.54	-55 ~ 125	50	100	3.3	0.095	AEC-Q200, CE, cURus
0680L1500-25	Bel Fuse	Active	1.5	125	125	Slow Blow	2-SMD, Square End Block	6.10 x 2.54 x 2.54	-55 ~ 125	50	100	3.3	0.095	AEC-Q200, CE, cURus
0680L1500-01	Bel Fuse	Active	1.5	125	125	Slow Blow	2-SMD, Square End Block	6.10 x 2.54 x 2.54	-55 ~ 125	50	100	3.3	0.095	AEC-Q200, CE, cURus
0680L1500-05	Bel Fuse	Active	1.5	125	125	Slow Blow	2-SMD, Square End Block	6.10 x 2.54 x 2.54	-55 ~ 125	50	100	3.3	0.095	AEC-Q200, CE, cURus
0680H1500-01	Bel Fuse Inc.	Active	1.5	125	125	Slow Blow	2-SMD, Square End Block	6.10 x 2.54 x 2.54	-55 ~ 125	100	500	1.7	0.175	cURus
0680H1500-05	Bel Fuse Inc.	Active	1.5	125	125	Slow Blow	2-SMD, Square End Block	6.10 x 2.54 x 2.54	-55 ~ 125	100	500	1.7	0.175	cURus
044901.5MR	Littelfuse Inc.	Active	1.5	125	125	Slow Blow	2-SMD, Square End Block	6.10 x 2.69 x 2.69	-55 ~ 125	50	—	4.7	0.1186	cULus, PSE
045201.5MRL	Littelfuse Inc.	Active	1.5	125	125	Slow Blow	2-SMD, Square End Block	6.10 x 2.69 x 2.69	-55 ~ 125	50	—	3.65	0.093	CSA, PSE, UR

Engineering Selection Recommendations

For Direct Replacement (Preferred): The 0680L series (0680L1500-11, 0680L1500-15, 0680L1500-21, 0680L1500-25, 0680L1500-01, 0680L1500-05) from Bel Fuse Inc. are the primary substitutes. All maintain active product status, identical electrical and mechanical specifications, and enhanced DC breaking capacity (100 A DC versus unspecified for SST 1.5/5K). These parts carry AEC-Q200 certification, maintaining automotive-grade reliability. The 0680L1500-05 variant offers the highest inventory availability (42,143 pieces).

For Enhanced Performance Requirements: The 0680H series (0680H1500-01, 0680H1500-05) provides superior breaking capacity (100 A AC, 500 A DC) and lower melting I²t (1.7 versus 3.3), suitable for applications requiring higher fault current withstand capability. These parts carry cURus certification and are active status.

For Alternative Manufacturer Sourcing: Littelfuse NANO²® series parts (044901.5MR, 045201.5MRL) provide functional equivalence with different approval agency certifications (cULus/PSE and CSA/PSE/UR respectively). Note that these parts have slightly larger width and height dimensions (2.69 mm versus 2.54 mm), which may require PCB layout verification. The 045201.5MRL variant offers the highest inventory availability among Littelfuse options (40,200 pieces).

Frequently Asked Questions (FAQ)

Q: Can I use 0680L series parts as direct replacements for SST 1.5/5K?

A: Yes. The 0680L series maintains identical current rating (1.5 A), voltage ratings (125 V AC/DC), response time (Slow Blow), mounting type (Surface Mount), and package dimensions (6.10 x 2.54 x 2.54 mm). All are ROHS3 compliant with MSL 1 rating. The primary difference is active product status and enhanced DC breaking capacity (100 A DC).

Q: What is the difference between 0680L and 0680H series?

A: Both series meet the mandatory electrical parameters (1.5 A, 125 V AC/DC, Slow Blow). The 0680H series offers higher breaking capacity (100 A AC, 500 A DC versus 50 A AC, 100 A DC) and lower melting I²t (1.7 versus 3.3). The 0680H series carries only cURus certification, while 0680L carries AEC-Q200, CE, and cURus certifications.

Q: Are Littelfuse NANO²® parts compatible with SST 1.5/5K footprints?

A: Electrical compatibility is confirmed (1.5 A, 125 V AC/DC, Slow Blow, Surface Mount). However, the Littelfuse parts have slightly larger dimensions (2.69 mm width and height versus 2.54 mm). PCB layout verification is required to confirm mechanical fit within existing footprints.

Q: Which substitute part has the best inventory availability?

A: The 0680L1500-05 from Bel Fuse Inc. has the highest inventory (42,143 pieces), followed by 045201.5MRL from Littelfuse Inc. (40,200 pieces).

Q: Do all substitute parts meet the same approval certifications as SST 1.5/5K?

A: No. The SST 1.5/5K carries AEC-Q200, CE, CSA, and cULus certifications. The 0680L series carries AEC-Q200, CE, and cURus. The 0680H series carries only cURus. Littelfuse parts carry different certification combinations (cULus/PSE or CSA/PSE/UR). Application-specific certification requirements must be verified before selection.

Q: What is the significance of the part number suffix (e.g., -11, -15, -21, -25)?

A: The suffix indicates packaging and tape configuration variants within the 0680L series. All variants maintain identical electrical and mechanical specifications. Selection should be based on assembly equipment compatibility and packaging requirements.

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