SSQ 3 /5K Surface Mount Fuse - Equivalent & Substitute Parts

Part Overview

The SSQ 3 /5K is a 3A 125VAC/VDC 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 production and maintenance applications. The fuse provides fast-blow response with 50A AC and 300A DC breaking capacity, suitable for circuit protection in industrial and commercial electronics requiring 125V AC/DC operation.

Substiute Parts

SSQ 3 /5K

Bel Fuse Inc.In Stock: 965SSQ 3 /5K Datasheet

Current PartRFQ

0679L3000-05

Bel Fuse Inc.In Stock: 1305220679L3000-05 Datasheet

DirectRFQ

SSQ 3

Bel Fuse Inc.In Stock: 2148SSQ 3 Datasheet

Parametric EquivalentRFQ

0476003.MR

Littelfuse Inc.In Stock: 21390476003.MR Datasheet

DirectRFQ

0476003.MRSN

Littelfuse Inc.In Stock: 7450476003.MRSN Datasheet

DirectRFQ

0451003.MRSN

Littelfuse Inc.In Stock: 14720451003.MRSN Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitute parts for the SSQ 3 /5K are grouped based on strict electrical and mechanical compatibility criteria:

Direct Electrical Equivalents maintain identical current rating (3A), voltage ratings (125VAC/125VDC), response time (fast blow), and package configuration (2-SMD square end block). These parts are interchangeable without circuit redesign.

Parametric Equivalents share the same electrical specifications but may differ in series designation, product status, or packaging format while maintaining functional compatibility.

Higher Voltage Rated Substitutes exceed the original 125VAC rating (250VAC) while maintaining 125VDC and 3A current rating. These provide enhanced voltage margin and are backward compatible for 125VAC applications.

Key substitution parameters:

• Current Rating: 3 A (mandatory match)
• Voltage Rating - AC: 125 V minimum
• Voltage Rating - DC: 125 V (mandatory match)
• Mounting Type: Surface Mount (mandatory match)
• Package / Case: 2-SMD, Square End Block (mandatory match)
• Response Time: Fast Blow (mandatory match)

Parameter Comparison

Engineering Selection Recommendations

0679L3000-05 (Bel Fuse Inc., Active Status) is the primary direct substitute. It maintains identical electrical specifications and package configuration as the SSQ 3 /5K. The part is currently in active production with 130,446 units in stock, ensuring long-term availability. AEC-Q200 qualification provides automotive-grade reliability. The melting I²t value of 1.8 is lower than the original 3, indicating faster thermal response. This part is suitable for direct replacement in new designs and production continuations.

SSQ 3 (Bel Fuse Inc., Obsolete Status) is a parametric equivalent with identical electrical and mechanical specifications to the SSQ 3 /5K. However, both parts share obsolete status, making this option unsuitable for long-term supply chain planning. Use only if existing inventory is available and no active alternatives are required.

0476003.MR and 0476003.MRSN (Littelfuse Inc., Active Status) provide enhanced voltage rating at 250VAC while maintaining 125VDC and 3A current rating. Both parts are functionally compatible for 125VAC applications with improved voltage margin. The 100A AC breaking capacity exceeds the original 50A AC specification. These parts are suitable for applications requiring higher AC voltage headroom. Littelfuse NANO²®476 series certification includes cURus approval.

0451003.MRSN (Littelfuse Inc., Active Status) maintains 125VAC/125VDC ratings and 3A current with identical package configuration. This part is suitable for direct substitution in circuits operating at the original voltage specifications. CSA, METI, and UR certifications provide broad regulatory coverage. The lower DC cold resistance of 0.0227 Ohms indicates minimal voltage drop characteristics.

Frequently Asked Questions (FAQ)

Q: Can I use 0476003.MR or 0476003.MRSN as a direct replacement for SSQ 3 /5K?

A: Yes. Both parts maintain the required 3A current rating, 125VDC voltage rating, fast-blow response, and 2-SMD square end block package. The 250VAC rating provides enhanced voltage margin for 125VAC applications. No circuit redesign is required.

Q: What is the difference between 0679L3000-05 and SSQ 3?

A: Both parts are electrically and mechanically identical. The primary difference is product status: 0679L3000-05 is active with high inventory availability, while SSQ 3 is obsolete. For new production, 0679L3000-05 is the recommended choice.

Q: Why do some substitute parts have different melting I²t values?

A: Melting I²t represents the thermal energy required to melt the fuse element. Lower values indicate faster thermal response. Substitutes with lower I²t values (1.65–1.8 versus original 3) provide faster protection but remain functionally compatible for the specified 3A current rating and voltage conditions.

Q: Are 0476003.MR and 0476003.MRSN interchangeable?

A: Yes. Both parts are identical except for packaging format. 0476003.MR is supplied in Tape & Reel format, while 0476003.MRSN is also Tape & Reel. Verify packaging requirements for your assembly process.

Q: What certifications should I verify for my application?

A: The original SSQ 3 /5K carries CE, CSA, and cULus certifications. Substitute parts maintain equivalent or enhanced certifications: 0679L3000-05 includes AEC-Q200 and cURus; Littelfuse parts (0476003 series and 0451003.MRSN) include cURus, CSA, METI, or UR approvals. Verify that selected substitute certifications meet your application requirements.

Q: Can I mix different substitute parts in the same circuit board?

A: Yes, provided all parts meet the circuit's electrical requirements (3A, 125VDC minimum, 125VAC minimum). However, for consistency and supply chain management, standardizing on a single active substitute part is recommended.