Equivalent & Substitute Parts for 0665.250ZRLL

Part Overview

The Littelfuse 0665.250ZRLL is a 250 mA, 250 V AC/DC board mount radial fuse from the LT-5™ 665 series. This component is classified as obsolete, making identification of active equivalent parts essential for ongoing design support and procurement. The part operates within a -40°C to 85°C temperature range and meets ROHS3 compliance requirements. Due to its obsolete status, active substitute parts from current manufacturing lines are necessary for new designs and production continuity.

Substiute Parts

0665.250ZRLL

Littelfuse Inc.In Stock: 11070665.250ZRLL Datasheet

Current PartRFQ

37402500000

Littelfuse Inc.In Stock: 236337402500000 Datasheet

DirectRFQ

0034.7109

SCHURTER Inc.In Stock: 8230034.7109 Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the 0665.250ZRLL is determined by strict equivalence across the following critical parameters:

• Current Rating: 250 mA (exact match required)
• Voltage Rating (AC): 250 V (exact match required)
• Fuse Type: Board Mount, Through Hole configuration
• Package / Case: Radial, Can, Vertical form factor
• Response Time: Slow Blow characteristic
• Breaking Capacity: 50A @ rated voltage
• Operating Temperature: -40°C ~ 85°C range
• RoHS Compliance: ROHS3 Compliant

Two active substitute parts meet these criteria: the Littelfuse 37402500000 (TR5® 374 series) and the SCHURTER 0034.7109 (MSTU 250 series). Both parts maintain identical electrical ratings and mechanical compatibility with the original design.

Parameter Comparison

Engineering Selection Recommendations

Both substitute parts are active products with current manufacturing support, providing design continuity for applications previously using the obsolete 0665.250ZRLL.

The Littelfuse 37402500000 (TR5® 374 series) maintains Littelfuse manufacturer continuity and carries dual CSA and cULus certifications. This part exhibits a lower melting I²t value (0.17 versus 0.258), indicating faster thermal response characteristics within the slow-blow classification. Height dimension is reduced to 8.00mm compared to the original 8.45mm. This substitute is suitable for designs where manufacturer consistency and certification scope are prioritized.

The SCHURTER 0034.7109 (MSTU 250 series) provides cross-manufacturer substitution with cULus certification. This part maintains identical melting I²t (0.258) and physical diameter (8.50mm) as the original, with height matching at 8.50mm. This substitute is suitable for designs where thermal response characteristics and dimensional consistency with the original part are critical.

Both parts satisfy all mandatory electrical and mechanical parameters. Selection between them depends on specific design requirements regarding thermal response, certification scope, and dimensional constraints within the PCB layout.

Frequently Asked Questions (FAQ)

Q: Can the Littelfuse 37402500000 be used as a direct replacement for the 0665.250ZRLL?

A: Yes. Both parts share identical current rating (250 mA), voltage rating (250 V AC), response time (Slow Blow), breaking capacity (50A), and operating temperature range (-40°C ~ 85°C). The 37402500000 is an active product with current manufacturing support. Minor dimensional variation in height (8.00mm versus 8.45mm) must be verified against PCB layout constraints.

Q: What is the difference between the Littelfuse and SCHURTER substitutes?

A: The Littelfuse 37402500000 exhibits lower melting I²t (0.17) compared to both the original part and the SCHURTER 0034.7109 (0.258), resulting in faster thermal response within the slow-blow classification. The SCHURTER part maintains identical melting I²t and closer dimensional alignment to the original. Both meet all electrical specifications and certifications required for 250 mA, 250 V applications.

Q: Are there packaging considerations when selecting a substitute?

A: Yes. The Littelfuse 37402500000 is supplied in Cut Tape (CT) packaging, while the SCHURTER 0034.7109 is supplied in Bulk packaging. Procurement volume and assembly line requirements should guide packaging selection.

Q: Do all substitute parts meet RoHS compliance?

A: Yes. Both the Littelfuse 37402500000 and SCHURTER 0034.7109 are ROHS3 Compliant, matching the compliance status of the original 0665.250ZRLL.

Q: What certifications apply to each substitute part?

A: The Littelfuse 37402500000 carries CSA and cULus certifications. The SCHURTER 0034.7109 carries cULus certification. Both certifications are recognized for board mount fuse applications in the specified voltage and current range.