Littelfuse 0664.800ZRLL Board Mount Fuse Equivalent & Substitute Parts

Part Overview

The Littelfuse 0664.800ZRLL is an 800 mA, 250 V AC/DC board mount fuse with radial, can-style vertical mounting. This component belongs to the LT-5™ 664 series and features slow-blow response characteristics suitable for circuit protection applications requiring controlled inrush current tolerance.

The 0664.800ZRLL is classified as obsolete. Identifying equivalent and substitute parts is necessary to maintain design continuity, ensure supply chain availability, and support ongoing production or maintenance requirements for systems utilizing this fuse specification.

Substiute Parts

0664.800ZRLL

Littelfuse Inc.In Stock: 9430664.800ZRLL Datasheet

Current PartRFQ

37208000001

Littelfuse Inc.In Stock: 309737208000001 Datasheet

MFR RecommendedRFQ

0034.6914

SCHURTER Inc.In Stock: 12200034.6914 Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the 0664.800ZRLL is determined by strict alignment with the following electrical and mechanical parameters:

• Current Rating: 800 mA (exact match required)
• Voltage Rating (AC): 250 V (exact match required)
• Response Time: Slow Blow (exact match required)
• Mounting Type: Through Hole (exact match required)
• Fuse Type: Board Mount, Cartridge Style Excluded (exact match required)
• Package / Case: Radial, Can, Vertical (exact match required)
• Operating Temperature Range: -40°C ~ 85°C (exact match required)
• RoHS Compliance: ROHS3 Compliant (exact match required)

Two substitute parts meet these criteria:

1. 37208000001 (Littelfuse Inc., TR5® 372 series) – MFR Recommended substitute with active product status
2. 0034.6914 (SCHURTER Inc., MXT 250 series) – Direct manufacturer alternative with active product status

Parameter Comparison

Engineering Selection Recommendations

Both substitute parts satisfy the mandatory electrical and mechanical parameters for direct replacement of the obsolete 0664.800ZRLL.

37208000001 (Littelfuse TR5® 372) is designated as the MFR Recommended substitute. This part maintains Littelfuse manufacturer continuity and carries active product status, ensuring long-term availability and supply chain stability. The part holds ROHS3 compliance and REACH Unaffected status. Dimensional variation is minimal (height difference of 0.018" / 0.45mm). The higher melting I²t value (5.76 vs. 2.2) indicates a slightly different thermal response profile within the slow-blow classification.

0034.6914 (SCHURTER MXT 250) provides an alternative from a different manufacturer with active product status. This part matches the breaking capacity specification (100A) of the original 0664.800ZRLL and carries ROHS3 compliance with REACH Unaffected status. Dimensional variation is minimal (height difference of 0.002" / 0.05mm). The lower melting I²t value (1.5 vs. 2.2) indicates a faster thermal response within the slow-blow classification.

Selection between these substitutes depends on design requirements regarding thermal response characteristics, manufacturer preference, and supply chain considerations. Both parts are electrically and mechanically compatible with the original specification.

Frequently Asked Questions (FAQ)

Q: Can 37208000001 and 0034.6914 be used interchangeably with the 0664.800ZRLL?

A: Both parts meet all mandatory electrical and mechanical parameters: 800 mA current rating, 250 V AC voltage rating, slow-blow response, through-hole mounting, radial can-style vertical package, and -40°C to 85°C operating temperature range. Physical dimensions are within acceptable tolerance for standard PCB footprints. Both are ROHS3 compliant. Interchangeability is confirmed for these core specifications.

Q: What is the significance of the different melting I²t values?

A: Melting I²t describes the thermal energy required to melt the fuse element. The 0664.800ZRLL specifies 2.2, while 37208000001 specifies 5.76 and 0034.6914 specifies 1.5. All three remain classified as slow-blow fuses. The variation reflects different fuse element designs within the slow-blow category. Circuit protection performance depends on the specific inrush current profile and duration of the protected application. Verify that the substitute's I²t value is appropriate for your circuit's transient behavior.

Q: What is the difference between the breaking capacity ratings?

A: Breaking capacity indicates the maximum fault current the fuse can safely interrupt at rated voltage. The 0664.800ZRLL and 0034.6914 both specify 100A breaking capacity, while 37208000001 specifies 35A. For applications where fault currents may exceed 35A, the 0034.6914 or continued use of 0664.800ZRLL stock is required. For typical low-fault-current applications, 37208000001 is adequate.

Q: Are there packaging differences between the substitutes?

A: Yes. The 0664.800ZRLL packaging is listed as "-" (unspecified). The 37208000001 is supplied in Cut Tape (CT) packaging, while 0034.6914 is supplied in Bulk packaging. Packaging affects order quantities, handling, and integration into automated assembly processes. Confirm packaging compatibility with your procurement and assembly requirements.

Q: Which substitute has better long-term availability?

A: Both 37208000001 and 0034.6914 carry active product status, indicating ongoing manufacturer support. The 37208000001 is designated as the MFR Recommended substitute by Littelfuse, suggesting prioritized support within the Littelfuse product portfolio. For critical applications requiring maximum supply chain certainty, the MFR Recommended part is the preferred choice.

Q: Do all parts meet the same regulatory certifications?

A: No. The 0664.800ZRLL lists CSA, KTL, SEMKO, UL, and VDE approvals. The 37208000001 lists CCC, cURus, SEMKO, and VDE approvals. The 0034.6914 lists CCC, cURus, KC, and VDE approvals. Verify that the substitute's certification set meets your application's regulatory requirements, particularly if UL or CSA certification is mandatory.