SST 4.6 Equivalent & Substitute Parts

Part Overview

The SST 4.6 is a 4.6 A surface mount board mount fuse rated for 125 V AC/DC operation with slow blow response characteristics. Manufactured by Bel Fuse Inc., this component is classified as obsolete. Due to its obsolete status, direct replacement with active production alternatives is necessary for new designs and ongoing procurement. Substitute parts maintain identical electrical ratings and mechanical form factors while offering improved availability and extended product lifecycle support.

Key Parameters

Parameter	Value
Current Rating	4.6 A
Voltage Rating (AC)	125 V
Voltage Rating (DC)	125 V
Response Time	Slow Blow
Mounting Type	Surface Mount
Package / Case	2-SMD, Square End Block
Size / Dimension	0.240" L x 0.100" W x 0.100" H (6.10mm x 2.54mm x 2.54mm)
Operating Temperature	-55°C ~ 125°C
RoHS Status	ROHS3 Compliant
Moisture Sensitivity Level (MSL)	1 (Unlimited)

Substitute Part Grouping Explanation

Substitution for SST 4.6 is determined by strict equivalence across the following parameters:

Primary Substitution Criteria:

Current Rating: 4.6 A (exact match required)
Voltage Rating: 125 V AC and 125 V DC (exact match required)
Response Time: Slow Blow (exact match required)
Mounting Type: Surface Mount (exact match required)
Package / Case: 2-SMD, Square End Block (exact match required)
Physical Dimensions: 0.240" L x 0.100" W x 0.100" H (exact match required)
Operating Temperature Range: -55°C ~ 125°C (exact match required)
RoHS Compliance: ROHS3 Compliant (exact match required)

Substitute Categories:

Direct Manufacturer Substitutes (Bel Fuse 0680L Series): Parts 0680L3500-01, 0680L3500-05, 0680L3500-11, 0680L3500-15, 0680L3500-21, and 0680L3500-25 are active production equivalents from Bel Fuse Inc. These parts maintain all primary electrical and mechanical parameters. Differences in Breaking Capacity (50A AC, 100A DC vs. 50A) and DC Cold Resistance (0.03 Ohms vs. 0.027 Ohms) do not affect substitutability within the specified application envelope. Packaging differs (Tape & Reel vs. Cut Tape), allowing selection based on procurement requirements.

Parametric Equivalents (Bel Fuse 0680H Series): Parts 0680H3500-01 and 0680H3500-05 meet all primary substitution criteria. These parts feature enhanced Breaking Capacity (100A AC, 500A DC) and lower Melting I²t (12 vs. 18), representing a higher performance variant suitable for applications requiring increased fault current handling. Approval Agency coverage differs (cURus only vs. AEC-Q200, CE, CSA, cULus), requiring verification against application compliance requirements.

Cross-Manufacturer Substitutes (Littelfuse NANO²® Series): Parts 044904.6MR, 045204.6MRL, and 045204.6NRL from Littelfuse Inc. maintain all primary electrical and mechanical parameters. Physical dimensions show minor variation (0.106" W x 0.106" H vs. 0.100" W x 0.100" H), remaining within standard PCB footprint tolerances. Melting I²t values differ (26.53–32.7 vs. 18), and approval agencies vary (CSA, PSE, UR vs. AEC-Q200, CE, CSA, cULus), requiring application-specific validation.

Parameter Comparison

Part Number	Manufacturer	Series	Current Rating (A)	Voltage AC (V)	Voltage DC (V)	Response Time	Package	Size (mm)	Breaking Capacity AC	Breaking Capacity DC	Melting I²t	DC Cold Resistance (Ω)	Product Status	Inventory (Pcs)
SST 4.6	Bel Fuse Inc.	SST	4.6	125	125	Slow Blow	2-SMD, Square End Block	6.10 x 2.54 x 2.54	50A	—	18	0.027	Obsolete	1037
0680L3500-01	Bel Fuse Inc.	0680L	4.6	125	125	Slow Blow	2-SMD, Square End Block	6.10 x 2.54 x 2.54	50A	100A	18	0.03	Active	2459
0680L3500-05	Bel Fuse Inc.	0680L	4.6	125	125	Slow Blow	2-SMD, Square End Block	6.10 x 2.54 x 2.54	50A	100A	18	0.03	Active	10522
0680L3500-11	Bel Fuse Inc.	0680L	4.6	125	125	Slow Blow	2-SMD, Square End Block	6.10 x 2.54 x 2.54	50A	100A	18	0.03	Active	929
0680L3500-15	Bel Fuse Inc.	0680L	4.6	125	125	Slow Blow	2-SMD, Square End Block	6.10 x 2.54 x 2.54	50A	100A	18	0.03	Active	1027
0680L3500-21	Bel Fuse Inc.	0680L	4.6	125	125	Slow Blow	2-SMD, Square End Block	6.10 x 2.54 x 2.54	50A	100A	18	0.03	Active	705
0680L3500-25	Bel Fuse Inc.	0680L	4.6	125	125	Slow Blow	2-SMD, Square End Block	6.10 x 2.54 x 2.54	50A	100A	18	0.03	Active	936
0680H3500-01	Bel Fuse Inc.	0680H	4.6	125	125	Slow Blow	2-SMD, Square End Block	6.10 x 2.54 x 2.54	100A	500A	12	0.042	Active	1138
0680H3500-05	Bel Fuse Inc.	0680H	4.6	125	125	Slow Blow	2-SMD, Square End Block	6.10 x 2.54 x 2.54	100A	500A	12	0.042	Active	5435
044904.6MR	Littelfuse Inc.	NANO²® 449	4.6	125	125	Slow Blow	2-SMD, Square End Block	6.10 x 2.69 x 2.69	50A	—	32.7	0.0261	Active	1915
045204.6MRL	Littelfuse Inc.	NANO²® 452	4.6	125	125	Slow Blow	2-SMD, Square End Block	6.10 x 2.69 x 2.69	50A	—	26.53	0.0224	Active	18148

Engineering Selection Recommendations

Bel Fuse 0680L Series (0680L3500-01, 0680L3500-05, 0680L3500-11, 0680L3500-15, 0680L3500-21, 0680L3500-25): These parts are the primary recommended substitutes for SST 4.6. All variants maintain identical electrical specifications and mechanical form factors. Selection among these part numbers is determined by packaging and lead time requirements. Approval agencies include AEC-Q200, CE, and cURus certifications, supporting automotive and industrial applications. High inventory availability (705–10,522 pcs) ensures procurement reliability.

Bel Fuse 0680H Series (0680H3500-01, 0680H3500-05): These parts are suitable for applications requiring enhanced fault current handling (100A AC, 500A DC breaking capacity). The reduced Melting I²t (12 vs. 18) indicates faster response to overcurrent conditions. Approval coverage is limited to cURus certification. Selection of this variant requires confirmation that the application environment and circuit design accommodate the different thermal and electrical response characteristics.

Littelfuse NANO²® Series (044904.6MR, 045204.6MRL): These cross-manufacturer alternatives maintain all primary electrical ratings and mechanical compatibility. Physical dimensions show minor variation (0.106" vs. 0.100" width and height), which remains within standard PCB footprint design tolerances. Approval agencies differ (CSA, PSE, UR for 045204.6MRL; cURus, PSE for 044904.6MR), requiring validation against specific application compliance requirements. The 045204.6MRL variant offers the highest inventory availability (18,148 pcs) among all substitutes.

Frequently Asked Questions (FAQ)

Q: Can I use 0680L3500 series parts as direct replacements for SST 4.6?

A: Yes. The 0680L3500 series (all variants: -01, -05, -11, -15, -21, -25) are direct functional equivalents. All maintain 4.6 A current rating, 125 V AC/DC voltage rating, slow blow response, surface mount configuration, and identical physical dimensions. The primary difference is packaging format (Tape & Reel vs. Cut Tape). Selection among these variants depends on procurement and assembly requirements.

Q: What is the difference between 0680L and 0680H series?

A: Both series maintain identical electrical ratings (4.6 A, 125 V AC/DC, slow blow). The 0680H series features higher breaking capacity (100A AC, 500A DC vs. 50A AC, 100A DC) and lower Melting I²t (12 vs. 18). This indicates faster response to fault conditions and enhanced capability for high-fault-current environments. Selection depends on circuit design requirements and fault current levels in the application.

Q: Are Littelfuse NANO²® parts compatible with SST 4.6 footprints?

A: Littelfuse NANO²® parts (044904.6MR, 045204.6MRL) maintain the same electrical specifications and primary dimensions (0.240" length). Width and height dimensions are 0.106" versus 0.100" for SST 4.6. This 0.006" variation per side remains within standard PCB footprint design tolerances and does not prevent physical mounting. Electrical performance is equivalent. Verify PCB layout constraints before selection.

Q: Which substitute offers the best availability?

A: The 045204.6MRL (Littelfuse NANO²® 452) offers the highest inventory availability at 18,148 pcs. Among Bel Fuse alternatives, 0680L3500-05 provides strong availability at 10,522 pcs. Both are active production parts with established supply chains.

Q: Do all substitutes have the same approval certifications?

A: No. SST 4.6 carries AEC-Q200, CE, CSA, and cULus certifications. Bel Fuse 0680L series maintains AEC-Q200, CE, and cURus. Bel Fuse 0680H series carries cURus only. Littelfuse 045204.6MRL carries CSA, PSE, and UR. Littelfuse 044904.6MR carries cURus and PSE. Application compliance requirements determine which substitute is appropriate.

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

A: Yes, provided all selected parts meet the application's electrical and compliance requirements. Bel Fuse 0680L variants are electrically and mechanically interchangeable. Mixing 0680L and 0680H series requires confirmation that the enhanced breaking capacity and different response characteristics of 0680H do not conflict with circuit design. Cross-manufacturer mixing (Bel Fuse and Littelfuse) is permissible if compliance certifications align with application requirements.

Q: What does "Melting I²t" represent, and why does it differ among substitutes?

A: Melting I²t is a thermal energy parameter indicating the fuse element's response to overcurrent. Lower values indicate faster response to fault conditions. SST 4.6 has Melting I²t of 18; 0680H series has 12 (faster response); Littelfuse variants range from 26.53 to 32.7 (slower response). Selection depends on circuit protection requirements and tolerance for transient overcurrent events.

Request Quote (Ships tomorrow)

Part Number

Quantity

Company

Contact Name

E-mail

Message