SST 2/5K Surface Mount Fuse – Equivalent & Substitute Parts

Part Overview

The SST 2/5K is a 2 A, 125 V AC/DC surface mount board fuse manufactured by Bel Fuse Inc. in a 2-SMD, square end block package. This component is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and production continuity. The fuse provides slow-blow response characteristics suitable for circuit protection in applications requiring 2 A rated current at 125 V AC or DC.

Substiute Parts

SST 2/5K

Bel Fuse Inc.In Stock: 1014SST 2/5K Datasheet

Current PartRFQ

0680L2000-01

Bel FuseIn Stock: 17520680L2000-01 Datasheet

DirectRFQ

0680L2000-05

Bel FuseIn Stock: 216070680L2000-05 Datasheet

DirectRFQ

0680L2000-11

Bel Fuse Inc.In Stock: 8890680L2000-11 Datasheet

DirectRFQ

0680L2000-15

Bel Fuse Inc.In Stock: 11010680L2000-15 Datasheet

DirectRFQ

0680L2000-21

Bel Fuse Inc.In Stock: 10740680L2000-21 Datasheet

DirectRFQ

0680L2000-25

Bel FuseIn Stock: 8360680L2000-25 Datasheet

DirectRFQ

0680H2000-01

Bel Fuse Inc.In Stock: 8840680H2000-01 Datasheet

Parametric EquivalentRFQ

0680H2000-05

Bel Fuse Inc.In Stock: 56060680H2000-05 Datasheet

Parametric EquivalentRFQ

0449002.MR

Littelfuse Inc.In Stock: 19770449002.MR Datasheet

DirectRFQ

0452002.MRL

Littelfuse Inc.In Stock: 1415410452002.MRL Datasheet

DirectRFQ

0452002.MRSN

LittelfuseIn Stock: 19040452002.MRSN Datasheet

DirectRFQ

0452002.NRL

Littelfuse Inc.In Stock: 127600452002.NRL Datasheet

DirectRFQ

0454002.MR

Littelfuse Inc.In Stock: 132660454002.MR Datasheet

DirectRFQ

0454002.NR

Littelfuse Inc.In Stock: 7380454002.NR Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution for the SST 2/5K is determined by strict electrical and mechanical compatibility criteria:

Primary Substitution Criteria:

• Current Rating: 2 A (exact match required)
• Voltage Rating: 125 V AC and 125 V DC (exact match required)
• Response Time: Slow Blow (exact match required)
• Package / Case: 2-SMD, Square End Block (exact match required)
• Mounting Type: Surface Mount (exact match required)
• Size / Dimension: 0.240" L x 0.100" W x 0.100" H (exact match required)
• Operating Temperature Range: -55°C ~ 125°C (exact match required)

Direct Manufacturer Substitutes (Bel Fuse 0680L series) meet all primary criteria and are classified as active products. These parts are functionally interchangeable with the obsolete SST 2/5K.

Parametric Equivalents (Bel Fuse 0680H series) match all primary electrical and mechanical parameters but differ in breaking capacity and melting I²t characteristics. These are suitable where the enhanced breaking capacity does not conflict with circuit design requirements.

Cross-Manufacturer Alternatives (Littelfuse NANO²® series) provide equivalent electrical ratings and package dimensions with minor dimensional variations (0.106" width and height versus 0.100"). These are suitable where dimensional tolerance permits.

Parameter Comparison

Engineering Selection Recommendations

Direct Substitutes (Bel Fuse 0680L Series): The 0680L2000 variants (0680L2000-01, 0680L2000-05, 0680L2000-11, 0680L2000-15, 0680L2000-21, 0680L2000-25) are the primary recommended substitutes for the obsolete SST 2/5K. All variants are active products with identical electrical specifications and are available in Tape & Reel packaging suitable for automated assembly. These parts carry AEC-Q200 and CE certifications matching the original part's compliance profile. The increased DC breaking capacity (100A DC versus unspecified in the original) provides enhanced circuit protection margins without affecting circuit operation.

Parametric Equivalents (Bel Fuse 0680H Series): The 0680H2000-01 and 0680H2000-05 are parametric equivalents meeting all primary electrical and mechanical criteria. These parts feature enhanced breaking capacity (100A AC, 500A DC) and lower melting I²t (3.6 versus 5–6 in the 0680L series). Selection of the 0680H series is appropriate where circuit design permits the faster response characteristic. Certification is limited to cURus; verify compliance requirements before selection.

Cross-Manufacturer Alternatives (Littelfuse NANO²® Series): The 0449002.MR (NANO²® 449) and 0452002.MRL (NANO²® 452) provide equivalent electrical ratings with minor package dimensional variations (0.106" width and height). These parts are suitable where PCB layout tolerances accommodate the slightly larger footprint. The 0452002.MRL offers the highest inventory availability (141,490 pcs) and is available in Cut Tape & Digi-Reel packaging. Verify certifications (cULus, PSE, CSA, UR) against design requirements before selection.

Frequently Asked Questions (FAQ)

Q: Can the 0680L2000 series directly replace the SST 2/5K without circuit redesign? A: Yes. The 0680L2000 variants are direct substitutes with identical current rating, voltage rating, response time, package, and dimensions. No circuit redesign is required. The increased DC breaking capacity provides additional protection margin.

Q: What is the difference between the 0680L and 0680H series? A: Both series meet the primary electrical and mechanical criteria for substitution. The 0680H series has higher breaking capacity (100A AC, 500A DC versus 50A AC, 100A DC) and lower melting I²t (3.6 versus 6). The 0680H provides faster response and is suitable where circuit design permits. Verify certifications; the 0680H carries only cURus approval versus AEC-Q200 and CE for the 0680L.

Q: Are Littelfuse NANO²® fuses compatible with the SST 2/5K footprint? A: The NANO²® series matches the electrical specifications and primary dimensions (0.240" length). However, width and height are 0.106" versus 0.100" for the SST 2/5K. Verify PCB layout tolerances before selection. These parts are suitable where dimensional tolerance permits.

Q: Which substitute offers the best inventory availability? A: The Littelfuse 0452002.MRL (NANO²® 452) has the highest inventory (141,490 pcs). Among Bel Fuse options, the 0680L2000-05 offers strong availability (21,535 pcs).

Q: Do all substitutes carry the same certifications as the SST 2/5K? A: No. The SST 2/5K 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 cULus, PSE, and CSA (0452002.MRL) or cULus and PSE (0449002.MR). Verify compliance requirements for your application.

Q: What packaging options are available? A: Bel Fuse 0680L and 0680H series are supplied in Tape & Reel (TR). Littelfuse 0449002.MR is supplied in Tape & Reel. Littelfuse 0452002.MRL is supplied in Cut Tape (CT) & Digi-Reel®. The original SST 2/5K was supplied in bulk packaging.

Q: Are all substitutes RoHS3 compliant? A: Yes. All listed substitutes are ROHS3 compliant with MSL 1 (Unlimited) moisture sensitivity rating, matching the original part's environmental compliance.