SSQ 6.3 Equivalent & Substitute Parts

Part Overview

The Bel Fuse Inc. SSQ 6.3 is a 6.3 A, 125 V AC/DC surface mount board mount fuse with fast blow response characteristics. This part is classified as obsolete, making equivalent substitute components necessary for ongoing design support and production continuity. The SSQ series has been superseded by active alternatives that maintain electrical and mechanical compatibility while offering improved availability and extended product lifecycle support.

Substiute Parts

SSQ 6.3

Bel Fuse Inc.In Stock: 1112SSQ 6.3 Datasheet

Current PartRFQ

0679L6300-01

Bel Fuse Inc.In Stock: 178850679L6300-01 Datasheet

DirectRFQ

045106.3MRL

LittelfuseIn Stock: 15136045106.3MRL Datasheet

DirectRFQ

047606.3MR

Littelfuse Inc.In Stock: 827047606.3MR Datasheet

DirectRFQ

047606.3MRSN

Littelfuse Inc.In Stock: 2305047606.3MRSN Datasheet

DirectRFQ

045106.3MRSN

Littelfuse Inc.In Stock: 3222045106.3MRSN Datasheet

SimilarRFQ

045306.3MR

Littelfuse Inc.In Stock: 10371045306.3MR Datasheet

SimilarRFQ

3404.0018.11

SCHURTER Inc.In Stock: 19033404.0018.11 Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the SSQ 6.3 is determined by strict equivalence across the following electrical and mechanical parameters:

• Current Rating: 6.3 A (exact match required)
• Voltage Rating: 125 V AC and 125 V DC (exact match required)
• Response Time: Fast Blow (exact match required)
• Mounting Type: Surface Mount (exact match required)
• Package / Case: 2-SMD configuration (exact match required)
• Operating Temperature Range: -55°C to 125°C (exact match required)
• RoHS Compliance: ROHS3 Compliant (exact match required)

Substitute parts are grouped into two categories:

Direct Substitutes maintain all electrical and mechanical parameters with identical or superior breaking capacity ratings and melting I²t characteristics. These parts are pin-compatible and footprint-compatible with the original SSQ 6.3.

Similar Substitutes maintain all critical electrical parameters and mounting characteristics but may differ in packaging format (Tape & Reel vs. Cut Tape vs. Bulk) or have minor dimensional variations within acceptable tolerance ranges. These parts are functionally equivalent for circuit protection applications.

Parameter Comparison

Engineering Selection Recommendations

Primary Recommendation: 0679L6300-01 (Bel Fuse Inc.)

The 0679L6300-01 is the direct successor to the SSQ 6.3 within the Bel Fuse product line. It maintains identical electrical ratings, breaking capacity, and DC cold resistance. Product status is active with extended lifecycle support. Approval agencies include AEC-Q200 and cURus certifications, providing automotive-grade reliability assurance. This part is recommended as the first choice for direct replacement in existing designs.

Secondary Recommendation: 045106.3MRL (Littelfuse NANO²® 451 Series)

The 045106.3MRL provides equivalent electrical performance with active product status and CSA, PSE, and UL approvals. The melting I²t value of 9.17 is lower than the original SSQ 6.3, indicating faster thermal response. DC cold resistance is marginally lower at 0.0096 Ω. This part is suitable for applications where Littelfuse component qualification is preferred.

Alternative Recommendation: 047606.3MR or 047606.3MRSN (Littelfuse NANO²®476 Series)

Both 047606.3MR and 047606.3MRSN offer enhanced breaking capacity (100A AC, 300A DC) compared to the original SSQ 6.3, providing superior fault protection margins. These parts are functionally equivalent with identical electrical ratings and operating temperature range. The 047606.3MRSN variant is available in higher inventory quantities (2,278 pcs) compared to 047606.3MR (775 pcs).

Packaging Considerations

• Tape & Reel (TR) packaging is standard for high-volume production and automated assembly
• Cut Tape (CT) packaging (045106.3MRSN) is suitable for lower-volume or mixed-component pick-and-place operations
• Bulk packaging (3404.0018.11) is available from SCHURTER but requires manual component handling

Frequently Asked Questions (FAQ)

Q: Can I use 045106.3MRSN as a direct replacement for SSQ 6.3?

A: The 045106.3MRSN is functionally equivalent for circuit protection but differs in two aspects: it is specified for 125 V AC only (DC voltage rating not provided in documentation), and it is supplied in Cut Tape packaging rather than standard Tape & Reel format. Verify DC voltage requirements in your application before selection.

Q: What is the difference between 047606.3MR and 047606.3MRSN?

A: Both parts are electrically and mechanically identical. The difference is in packaging and inventory availability. The 047606.3MRSN has higher stock levels (2,278 pcs vs. 775 pcs) and may offer better lead time performance.

Q: Why does 045306.3MR show no DC voltage rating?

A: The 045306.3MR specification indicates 125 V AC and 125 V DC in the detailed description but does not list a separate DC voltage value in the parameter table. This is a documentation variance. The part is rated for both AC and DC operation at 125 V.

Q: Is the SCHURTER 3404.0018.11 a suitable substitute?

A: The 3404.0018.11 maintains all critical electrical parameters and is approved by cURus. However, it uses a 2-SMD J-Lead package configuration rather than Square End Block, resulting in different PCB footprint dimensions (7.40mm L x 3.10mm W vs. 6.10mm L x 2.54mm W). PCB layout redesign is required for this substitution.

Q: What does the melting I²t value indicate for substitution purposes?

A: Melting I²t is a thermal energy parameter that characterizes fuse response speed. Lower I²t values indicate faster thermal response. The SSQ 6.3 has an I²t of 15, while most active substitutes range from 7.5 to 9.17. All listed substitutes provide acceptable thermal response characteristics for 6.3 A circuit protection applications.

Q: Are all substitute parts RoHS3 compliant?

A: All listed substitute parts are ROHS3 compliant. The original SSQ 6.3 is also ROHS3 compliant, ensuring environmental regulatory consistency across all options.