SSQ 1.25 Equivalent & Substitute Parts

Part Overview

The SSQ 1.25 is a 1.25 A surface mount board mount fuse rated for 125 V AC/DC operation with fast blow response characteristics. Manufactured by Bel Fuse Inc., this component is classified as obsolete product status. Due to its obsolete designation, equivalent and substitute parts from active manufacturers are necessary for new designs and ongoing production requirements. Substitute parts maintain the core electrical specifications while offering active product support and improved availability.

Substiute Parts

SSQ 1.25

Bel Fuse Inc.In Stock: 1118SSQ 1.25 Datasheet

Current PartRFQ

0679L1250-01

Bel Fuse Inc.In Stock: 31550679L1250-01 Datasheet

DirectRFQ

04511.25MRL

Littelfuse Inc.In Stock: 643704511.25MRL Datasheet

DirectRFQ

04761.25MR

Littelfuse Inc.In Stock: 88404761.25MR Datasheet

DirectRFQ

04761.25MRSN

LittelfuseIn Stock: 100504761.25MRSN Datasheet

DirectRFQ

04511.25MRSN

Littelfuse Inc.In Stock: 98404511.25MRSN Datasheet

SimilarRFQ

04531.25MR

Littelfuse Inc.In Stock: 534004531.25MR Datasheet

SimilarRFQ

3404.0010.11

SCHURTER Inc.In Stock: 9303404.0010.11 Datasheet

SimilarRFQ

3404.0010.22

SCHURTER Inc.In Stock: 9853404.0010.22 Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution logic for the SSQ 1.25 is based on the following critical parameters:

Primary Substitution Criteria (Electrical Equivalence):

• Current Rating: 1.25 A (exact match required)
• Voltage Rating AC: 125 V (minimum requirement)
• Voltage Rating DC: 125 V (minimum requirement)
• Response Time: Fast Blow
• Mounting Type: Surface Mount
• Fuse Type: Board Mount (Cartridge Style Excluded)

Secondary Compatibility Factors:

• Package / Case: 2-SMD configuration (Square End Block or J-Lead acceptable)
• Operating Temperature Range: -55°C to 125°C
• RoHS3 Compliance
• Approval Agencies: CSA, UL, cURus, or equivalent

Parts are grouped into two categories:

Direct Equivalents (Identical Electrical Specifications):

• 0679L1250-01 (Bel Fuse Inc.)
• 04511.25MRL (Littelfuse Inc.)
• 04511.25MRSN (Littelfuse Inc.)
• 04531.25MR (Littelfuse Inc.)
• 3404.0010.11 (SCHURTER Inc.)
• 3404.0010.22 (SCHURTER Inc.)

Higher Voltage Rated Alternatives (Backward Compatible):

• 04761.25MR (Littelfuse Inc.) – 250 V AC / 125 V DC
• 04761.25MRSN (Littelfuse Inc.) – 250 V AC / 125 V DC

Higher voltage rated parts are electrically compatible in 125 V AC/DC circuits and provide additional design margin.

Parameter Comparison

Engineering Selection Recommendations

For Direct Replacement (Identical Specifications):

Select 0679L1250-01 (Bel Fuse Inc.) as the primary equivalent. This part maintains identical electrical ratings (1.25 A, 125 V AC/DC, Fast Blow) with active product status and AEC-Q200 automotive qualification. Inventory availability is 3062 units.

For Littelfuse NANO²® Series (Active Production):

04511.25MRL, 04511.25MRSN, and 04531.25MR are functionally equivalent alternatives from Littelfuse with active product status. These parts carry CSA, PSE, and UL approvals. Melting I²t values (0.664) differ from the original SSQ 1.25 (0.33), indicating different thermal response characteristics within the fast blow classification. Select based on design thermal requirements and approval agency requirements.

For Higher Voltage Applications (Backward Compatible):

04761.25MR and 04761.25MRSN provide 250 V AC rating while maintaining 125 V DC and 1.25 A current specifications. These parts are electrically compatible in 125 V AC/DC circuits and offer increased design margin. Breaking capacity is 100A AC / 300A DC.

For J-Lead Package Configuration:

3404.0010.11 and 3404.0010.22 (SCHURTER OMF 125 series) provide equivalent electrical specifications with J-Lead package geometry. These parts carry cURus approval and 100A breaking capacity. Select when J-Lead footprint compatibility is required.

Compliance Considerations:

All substitute parts are ROHS3 compliant and REACH unaffected. Verify approval agency requirements (CSA, UL, cURus, PSE) against design specifications before final selection.

Frequently Asked Questions (FAQ)

Q: Can I use 04761.25MR or 04761.25MRSN as direct replacements for SSQ 1.25?

A: Yes. These parts are electrically compatible in 125 V AC/DC circuits. The higher AC voltage rating (250 V) does not affect operation at 125 V AC. Both parts maintain 1.25 A current rating and Fast Blow response. Select based on approval agency requirements and design margin preferences.

Q: What is the difference between Square End Block and J-Lead packages?

A: Square End Block (04511.25MRL, 04531.25MR, 04761.25MR) and J-Lead (3404.0010.11, 3404.0010.22) refer to different lead geometries and PCB footprints. Verify PCB layout compatibility before substitution. These are not interchangeable without board redesign.

Q: Why do Littelfuse parts have different Melting I²t values (0.664) compared to SSQ 1.25 (0.33)?

A: Melting I²t represents thermal energy required to melt the fuse element. Different values indicate different internal element designs while maintaining the same 1.25 A current rating and Fast Blow response classification. Both designs meet the fast blow specification but with different thermal characteristics. Verify thermal performance requirements for your specific application.

Q: Are all substitute parts ROHS3 compliant?

A: Yes. All listed substitute parts are ROHS3 compliant and REACH unaffected, matching the environmental compliance of the original SSQ 1.25.

Q: What approval agencies are represented in the substitute parts?

A: Substitute parts carry approvals from CSA, UL, cURus, PSE, and AEC-Q200. Verify that the selected substitute part carries the approval agencies required by your design specifications and regional standards.

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

A: All listed parts are electrically equivalent at 1.25 A, 125 V AC/DC with Fast Blow response. However, verify package compatibility (Square End Block vs. J-Lead) with your PCB layout. Do not mix different package types on the same board without layout verification.