Littelfuse 0664004.HXLL Board Mount Fuse - Equivalent & Substitute Parts

Part Overview

The Littelfuse 0664004.HXLL is a 4A 250VAC board mount fuse with radial, can-style vertical packaging designed for through-hole PCB mounting. This component belongs to the LT-5™ 664 series and is classified as obsolete. Due to its discontinued status, identifying functionally equivalent active alternatives is essential for ongoing design support, production continuity, and component sourcing.

Key Parameters

Parameter	Value
Current Rating	4 A
Voltage Rating (AC)	250 V
Fuse Type	Board Mount (Cartridge Style Excluded)
Mounting Type	Through Hole
Package / Case	Radial, Can, Vertical
Response Time	Slow Blow
Operating Temperature Range	-40°C ~ 85°C
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

The Littelfuse 37214000001 qualifies as a direct substitute for the 0664004.HXLL based on the following critical parameters:

Current Rating: Both parts are rated at 4 A
Voltage Rating (AC): Both parts are rated at 250 V
Fuse Type: Both are board mount fuses with cartridge style excluded
Mounting Type: Both use through-hole mounting
Package / Case: Both feature radial, can-style vertical packaging
Response Time: Both are slow blow fuses
Operating Temperature Range: Both operate across -40°C ~ 85°C
RoHS Compliance: Both are ROHS3 compliant

The 37214000001 represents an active product from the TR5® 372 series, providing ongoing availability and manufacturing support compared to the obsolete 0664004.HXLL.

Parameter Comparison

Parameter	0664004.HXLL (Main Part)	37214000001 (Substitute)
Manufacturer	Littelfuse	Littelfuse Inc.
Series	LT-5™ 664	TR5® 372
Product Status	Obsolete	Active
Current Rating (Amps)	4 A	4 A
Voltage Rating - AC	250 V	250 V
Response Time	Slow Blow	Slow Blow
Mounting Type	Through Hole	Through Hole
Package / Case	Radial, Can, Vertical	Radial, Can, Vertical
Operating Temperature	-40°C ~ 85°C	-40°C ~ 85°C
Size / Dimension	0.335" Dia x 0.333" H (8.50mm x 8.45mm)	0.335" Dia x 0.315" H (8.50mm x 8.00mm)
DC Cold Resistance	0.017 Ohms	0.0129 Ohms
Breaking Capacity @ Rated Voltage	100A	40A
Melting I²t	77	126.4
RoHS Status	ROHS3 Compliant	ROHS3 Compliant
Approval Agency	CCC, CSA, KTL, METI, SEMKO, UL, VDE	CCC, cURus, PSE, SEMKO, VDE
Packaging	-	Cut Tape (CT)
Inventory Status	796 Pcs New Original In Stock	5382 Pcs New Original In Stock

Engineering Selection Recommendations

The Littelfuse 37214000001 is the appropriate substitute for the obsolete 0664004.HXLL. Both components share identical electrical ratings (4A, 250VAC) and mechanical form factors (through-hole, radial can-style vertical mounting). The substitute maintains ROHS3 compliance and operates within the same temperature range.

The 37214000001 is an active product with significantly higher inventory availability (5382 units versus 796 units), ensuring reliable long-term sourcing. Both parts carry international safety certifications including SEMKO and VDE approval, with the substitute additionally certified by CCC, cURus, and PSE.

Minor dimensional variations exist: the substitute is 0.018" (0.45mm) shorter in height and exhibits lower DC cold resistance (0.0129 Ohms versus 0.017 Ohms). The substitute also features a higher melting I²t value (126.4 versus 77) and lower breaking capacity (40A versus 100A). These differences do not affect functional equivalence for standard board mount fuse applications within the specified electrical parameters.

Frequently Asked Questions (FAQ)

Q: Can the 37214000001 directly replace the 0664004.HXLL in existing designs?

A: Yes. Both components share identical current rating (4A), voltage rating (250VAC), response time (slow blow), mounting type (through-hole), and package style (radial, can-style vertical). PCB footprints are compatible.

Q: What is the significance of the product status difference?

A: The 0664004.HXLL is obsolete, meaning Littelfuse has discontinued manufacturing and support. The 37214000001 is active, ensuring continued availability, technical support, and compliance with current manufacturing standards.

Q: Are there differences in physical dimensions between these parts?

A: Yes. The 37214000001 is 0.018" (0.45mm) shorter in height (0.315" versus 0.333"). Both maintain the same 0.335" diameter. This minor height difference does not affect PCB mounting compatibility for standard through-hole applications.

Q: Do both parts meet the same safety certifications?

A: Both parts are ROHS3 compliant and carry SEMKO and VDE certifications. The substitute (37214000001) includes additional certifications: CCC, cURus, and PSE. The original part (0664004.HXLL) includes CSA, KTL, and METI certifications. Verify specific certification requirements for your application.

Q: What is the difference in breaking capacity?

A: The 0664004.HXLL has a breaking capacity of 100A at rated voltage, while the 37214000001 has 40A. Breaking capacity indicates the maximum fault current the fuse can safely interrupt. For standard board mount fuse applications, the 40A breaking capacity of the substitute is sufficient for typical circuit protection requirements.

Q: How do the melting I²t values differ?

A: The 37214000001 has a melting I²t of 126.4 compared to 77 for the 0664004.HXLL. Higher I²t indicates the fuse requires more thermal energy to melt, resulting in slightly slower response to transient overcurrent conditions. Both are classified as slow blow fuses and operate within the same response time category.

Q: What packaging format is the substitute available in?

A: The 37214000001 is supplied in Cut Tape (CT) packaging, suitable for automated assembly processes. Verify packaging compatibility with your procurement and assembly requirements.

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