SST 7/5K Surface Mount Board Mount Fuse Equivalent & Substitute Parts

Part Overview

The SST 7/5K is a 7 A, 125 V AC/DC surface mount board mount fuse manufactured by Bel Fuse Inc. in a 2-SMD, Square End Block package. This part is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and production continuity. The SST series has been superseded by active product lines offering improved electrical characteristics and broader approval agency certifications.

Key Parameters

Parameter	Value
Current Rating	7 A
Voltage Rating (AC)	125 V
Voltage Rating (DC)	125 V
Response Time	Slow Blow
Package / Case	2-SMD, Square End Block
Mounting Type	Surface Mount
Operating Temperature Range	-55°C ~ 125°C
Size / Dimension	0.240" L x 0.100" W x 0.100" H (6.10mm x 2.54mm x 2.54mm)
RoHS Status	ROHS3 Compliant
Moisture Sensitivity Level (MSL)	1 (Unlimited)

Substitute Part Grouping Explanation

Substitution for the SST 7/5K is determined by strict equivalence across the following critical parameters:

Mandatory Matching Parameters:

Current Rating: 7 A
Voltage Rating (AC): 125 V
Voltage Rating (DC): 125 V
Response Time: Slow Blow
Package / Case: 2-SMD, Square End Block
Mounting Type: Surface Mount
Operating Temperature Range: -55°C ~ 125°C
Size / Dimension: 0.240" L x 0.100" W x 0.100" H (6.10mm x 2.54mm x 2.54mm)

Direct Substitutes are parts from the 0680L series (0680L7000-01, 0680L7000-05, 0680L7000-11, 0680L7000-15, 0680L7000-21, 0680L7000-25) manufactured by Bel Fuse Inc. These parts maintain identical electrical and mechanical specifications while offering active product status and improved breaking capacity ratings.

Parametric Equivalents from the 0680H series (0680H7000-01, 0680H7000-05) meet all mandatory parameters but feature enhanced breaking capacity (100A AC, 500A DC versus 50A AC) and lower melting I²t values (48 versus 80). These are suitable where higher fault current withstand capability is required.

Similar Parts such as the 0452007.MRSN from Littelfuse Inc. share the same current rating, package, and mounting type but operate at reduced voltage (72 V AC/DC versus 125 V AC/DC). This part is suitable only for applications with lower voltage requirements.

Parameter Comparison

Part Number	Manufacturer	Series	Current Rating (A)	Voltage AC (V)	Voltage DC (V)	Response Time	Breaking Capacity AC (A)	Breaking Capacity DC (A)	Melting I²t	DC Cold Resistance (Ω)	Product Status	Approval Agency
SST 7/5K	Bel Fuse Inc.	SST	7	125	125	Slow Blow	50	—	80	0.011	Obsolete	AEC-Q200, CE, CSA, cULus
0680L7000-01	Bel Fuse	0680L	7	125	125	Slow Blow	50	100	68	0.012	Active	AEC-Q200, CE, cURus
0680L7000-05	Bel Fuse Inc.	0680L	7	125	125	Slow Blow	50	100	68	0.012	Active	AEC-Q200, CE, cURus
0680L7000-11	Bel Fuse	0680L	7	125	125	Slow Blow	50	100	68	0.012	Active	AEC-Q200, CE, cURus
0680L7000-15	Bel Fuse	0680L	7	125	125	Slow Blow	50	100	68	0.012	Active	AEC-Q200, CE, cURus
0680L7000-21	Bel Fuse	0680L	7	125	125	Slow Blow	50	100	68	0.012	Active	AEC-Q200, CE, cURus
0680L7000-25	Bel Fuse	0680L	7	125	125	Slow Blow	50	100	68	0.012	Active	AEC-Q200, CE, cURus
0680H7000-01	Bel Fuse Inc.	0680H	7	125	125	Slow Blow	100	500	48	0.015	Active	cURus
0680H7000-05	Bel Fuse Inc.	0680H	7	125	125	Slow Blow	100	500	48	0.015	Active	cURus
0452007.MRSN	Littelfuse Inc.	NANO²® 452	7	72	72	Slow Blow	50	—	123.83	0.0105	Active	CSA, UR

Engineering Selection Recommendations

For Direct Replacement (Preferred): The 0680L series (0680L7000-01, 0680L7000-05, 0680L7000-11, 0680L7000-15, 0680L7000-21, 0680L7000-25) provides the most straightforward substitution path. All variants maintain identical electrical specifications and package geometry. These parts carry active product status and retain AEC-Q200 certification, making them suitable for automotive and industrial applications. The 0680L series offers improved DC breaking capacity (100A DC) compared to the SST 7/5K, providing enhanced fault tolerance without affecting normal operation.

For Enhanced Fault Current Withstand: The 0680H series (0680H7000-01, 0680H7000-05) is appropriate when circuit design requires higher breaking capacity (100A AC, 500A DC). These parts maintain identical voltage and current ratings but feature lower melting I²t (48 versus 80), resulting in faster response to fault conditions. Note that 0680H series parts carry cURus certification only; applications requiring AEC-Q200 or CE certification should use the 0680L series.

For Reduced Voltage Applications: The 0452007.MRSN from Littelfuse Inc. is suitable only for circuits operating at 72 V AC/DC or lower. This part shares the same current rating and package but cannot be used in 125 V circuits due to voltage rating mismatch.

Frequently Asked Questions (FAQ)

Q: Can I use 0680L7000-05 as a direct replacement for SST 7/5K? A: Yes. The 0680L7000-05 meets all mandatory electrical and mechanical parameters: 7 A current rating, 125 V AC/DC voltage rating, slow blow response, identical package dimensions, and surface mount configuration. The part is in active production status with improved DC breaking capacity.

Q: What is the difference between the 0680L and 0680H series? A: Both series maintain identical voltage and current ratings. The 0680H series provides higher breaking capacity (100A AC, 500A DC versus 50A AC, 100A DC) and lower melting I²t (48 versus 68). Selection depends on circuit fault current requirements. The 0680L series retains broader certification coverage (AEC-Q200, CE, cURus), while 0680H carries cURus only.

Q: Why are there multiple part numbers within the 0680L series (0680L7000-01, -05, -11, -15, -21, -25)? A: These part numbers represent different packaging configurations or tape reel specifications. All variants share identical electrical and mechanical specifications for the 7 A, 125 V AC/DC fuse. Selection among these variants depends on procurement and assembly requirements.

Q: Can I use 0452007.MRSN in a 125 V circuit? A: No. The 0452007.MRSN is rated for 72 V AC/DC maximum. Using this part in a 125 V circuit exceeds its voltage rating and creates a safety hazard. This part is suitable only for applications with 72 V or lower voltage requirements.

Q: Are all substitute parts RoHS3 compliant? A: Yes. All parts listed—SST 7/5K, 0680L series, 0680H series, and 0452007.MRSN—carry ROHS3 Compliant status and MSL 1 (Unlimited) moisture sensitivity rating.

Q: What certifications should I verify for my application? A: The SST 7/5K carries AEC-Q200, CE, CSA, and cULus certifications. The 0680L series maintains AEC-Q200, CE, and cURus. The 0680H series carries cURus only. The 0452007.MRSN carries CSA and UR. Verify that substitute part certifications align with your application requirements before selection.

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