SSQ 7/5K Surface Mount Fuse - Equivalent & Substitute Parts

Part Overview

The SSQ 7/5K is a 7A 125VAC/VDC surface mount board fuse manufactured by Bel Fuse Inc. in a 2-SMD square end block package. This part is classified as obsolete, making substitute components necessary for new designs and ongoing production requirements. Equivalent parts maintain identical electrical ratings and mechanical compatibility while offering active product status and improved availability.

Key Parameters

Parameter	Value
Current Rating	7 A
Voltage Rating (AC)	125 V
Voltage Rating (DC)	125 V
Response Time	Fast Blow
Mounting Type	Surface Mount
Package / Case	2-SMD, Square End Block
Operating Temperature Range	-55°C to 125°C
RoHS Status	ROHS3 Compliant
Moisture Sensitivity Level	1 (Unlimited)

Substitute Part Grouping Explanation

Substitution eligibility is determined by strict equivalence across the following parameters: current rating (7A), AC voltage rating (125V), DC voltage rating (125V), response time (Fast Blow), mounting type (Surface Mount), and package configuration (2-SMD, Square End Block). All substitute parts listed maintain these core electrical and mechanical specifications.

Direct substitutes are classified into two categories:

Direct Equivalents (Identical Electrical & Mechanical Specifications): Parts that match all primary electrical ratings and physical dimensions within tolerance, enabling drop-in replacement without circuit modification.

Compatible Alternatives (Equivalent Electrical Ratings, Minor Dimensional Variance): Parts that maintain all electrical specifications with dimensional variations within acceptable manufacturing tolerances for the 2-SMD square end block package format.

Parameter Comparison

Parameter	SSQ 7/5K (Main)	0679L7000-05	0476007.MR	0476007.MRSN	0451007.MRSN
Manufacturer	Bel Fuse Inc.	Bel Fuse Inc.	Littelfuse Inc.	Littelfuse Inc.	Littelfuse Inc.
Current Rating (A)	7	7	7	7	7
Voltage Rating AC (V)	125	125	125	125	125
Voltage Rating DC (V)	125	125	125	125	—
Response Time	Fast Blow	Fast Blow	Fast Blow	Fast Blow	Fast Blow
Breaking Capacity AC (A)	50	50	100	100	50
Breaking Capacity DC (A)	300	300	300	300	—
Melting I²t	20	10.8	7.8	7.8	10.32
DC Cold Resistance (Ω)	0.009	0.01	0.0116	0.0116	0.009
Size L × W × H (mm)	6.10 × 2.54 × 2.54	6.10 × 2.54 × 2.79	6.10 × 2.69 × 2.69	6.10 × 2.69 × 2.69	6.10 × 2.69 × 2.69
Product Status	Obsolete	Active	Active	Active	Active
Packaging	—	Tape & Reel (TR)	Tape & Reel (TR)	Tape & Reel (TR)	Tape & Reel (TR)
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
REACH Status	REACH Unaffected	REACH Unaffected	REACH Affected	REACH Unaffected	REACH Unaffected

Engineering Selection Recommendations

0679L7000-05 (Bel Fuse Inc.): Active product status with highest inventory availability (40,980 pcs). Maintains identical manufacturer lineage and REACH unaffected status. Height dimension increases from 2.54mm to 2.79mm; verify PCB clearance in confined mounting areas. Melting I²t reduction (10.8 vs. 20) indicates faster thermal response; acceptable for applications with standard thermal margins.

0476007.MRSN (Littelfuse Inc., NANO²® 476 Series): Active product with REACH unaffected compliance. Dimensional increase to 2.69mm × 2.69mm requires PCB layout verification. Enhanced breaking capacity (100A AC vs. 50A AC) provides superior fault protection. Melting I²t of 7.8 represents fastest thermal response among substitutes; confirm circuit design accommodates reduced thermal time constant.

0476007.MR (Littelfuse Inc., NANO²® 476 Series): Functionally identical to 0476007.MRSN with REACH affected status. Evaluate supply chain and regulatory requirements for REACH affected components in target markets.

0451007.MRSN (Littelfuse Inc., NANO²® 451 Series): Active product with REACH unaffected status. DC voltage rating not specified in documentation; confirm 125V DC compatibility requirement before selection. Melting I²t of 10.32 provides intermediate thermal response. Dimensional compatibility identical to 0476007 series.

Frequently Asked Questions (FAQ)

Q: Can SSQ 7/5K be directly replaced with 0679L7000-05?

A: Yes. Both parts maintain 7A, 125VAC/VDC ratings and identical length (6.10mm). Height increases from 2.54mm to 2.79mm; verify clearance above component on PCB. Electrical performance is equivalent for standard circuit applications.

Q: What is the significance of melting I²t differences between substitutes?

A: Melting I²t defines thermal response speed. Lower values (7.8 for NANO²® 476 series) indicate faster fuse operation under fault conditions. Higher values (20 for SSQ 7/5K) allow greater inrush current tolerance. Select based on circuit inrush characteristics and protection requirements.

Q: Are Littelfuse NANO²® 476 and 451 series interchangeable?

A: Both maintain 7A, 125VAC ratings and identical physical footprint (6.10mm length). 0451007.MRSN lacks specified DC voltage rating; confirm 125V DC requirement before substitution. Breaking capacity differs (50A vs. 100A AC); select based on fault current levels in application.

Q: What is the impact of dimensional changes on PCB assembly?

A: SSQ 7/5K: 6.10 × 2.54 × 2.54mm. Littelfuse alternatives: 6.10 × 2.69 × 2.69mm. Length remains constant; width and height increase 0.15mm. Verify clearance to adjacent components and solder mask openings. No reflow profile modification required.

Q: Does REACH affected status (0476007.MR) restrict use?

A: REACH affected status indicates substance of concern presence. Regulatory restrictions depend on end-use market and application. Evaluate supply chain requirements; REACH unaffected alternatives (0679L7000-05, 0476007.MRSN, 0451007.MRSN) available for unrestricted markets.

Q: Which substitute offers best inventory availability?

A: 0679L7000-05 (Bel Fuse Inc.) maintains 40,980 pcs in stock, significantly exceeding other alternatives. Recommended for high-volume production with standard lead time requirements.

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