RUE800 Polymeric PTC Resettable Fuse Equivalent & Substitute Parts

Part Overview

The RUE800 is a polymeric PTC resettable fuse manufactured by Littelfuse, rated for 30V at 8A hold current with a radial, disc package configuration. This component is classified as obsolete, making equivalent and substitute parts necessary for ongoing system support and new designs. The RUE800 operates across a temperature range of -40°C to 85°C and provides automatic protection through polymeric PTC technology, resetting after fault conditions are cleared.

Substiute Parts

RUE800

LittelfuseIn Stock: 1066RUE800 Datasheet

Current PartRFQ

30R800UH

Littelfuse Inc.In Stock: 297130R800UH Datasheet

DirectRFQ

RUEF800

Littelfuse Inc.In Stock: 3194RUEF800 Datasheet

DirectRFQ

MF-R800

Bourns Inc.In Stock: 3880MF-R800 Datasheet

DirectRFQ

PFRA.800

SCHURTER Inc.In Stock: 806PFRA.800 Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution for the RUE800 is determined by strict electrical and mechanical parameter matching. All substitute parts must maintain the following core specifications: 30V maximum voltage rating, 8A hold current, 16A trip current, 5 mOhms minimum initial resistance, and radial disc through-hole mounting with 0.402" lead spacing. The operating temperature range of -40°C to 85°C and time-to-trip specification of 18.8 seconds are additional critical parameters for functional equivalence.

The substitute parts listed below meet these electrical requirements. Variations in post-trip resistance (R1), maximum current ratings, and physical dimensions (length and height) do not affect substitution eligibility when the core protection parameters remain within specification. Product status and compliance certifications are secondary considerations that may influence selection based on application requirements.

Parameter Comparison

Engineering Selection Recommendations

All four substitute parts—30R800UH, RUEF800, MF-R800, and PFRA.800—meet the core electrical and mechanical requirements for RUE800 replacement. Selection should be based on product availability, compliance certifications, and application-specific regulatory requirements.

For applications requiring RoHS3 compliance, all substitute parts qualify. The 30R800UH, RUEF800, and MF-R800 are available in higher quantities and carry broader certification coverage. The RUEF800 offers the highest maximum current rating at 100A, providing additional margin in applications with transient current conditions. The MF-R800 and PFRA.800 feature slightly elevated post-trip resistance specifications (30 mOhms maximum) compared to the RUE800 and 30R800UH (20 mOhms maximum), which may be relevant in low-impedance circuit designs.

Lead spacing tolerances are consistent across all parts at 0.402" (10.20mm), with the exception of RUEF800 at 0.400" (10.15mm), representing a negligible 0.05mm difference suitable for standard through-hole PCB layouts.

Frequently Asked Questions (FAQ)

Q: Can the 30R800UH directly replace the RUE800 in existing designs?

A: Yes. The 30R800UH maintains identical electrical specifications including 30V voltage rating, 8A hold current, 16A trip current, 5 mOhms initial resistance, and 18.8-second trip time. Physical dimensions and lead spacing are compatible with RUE800 PCB layouts. The primary difference is active product status and RoHS3 compliance.

Q: What is the significance of the different post-trip resistance values?

A: The RUE800 and 30R800UH specify 20 mOhms maximum post-trip resistance, while MF-R800 and PFRA.800 specify 30 mOhms. This parameter affects circuit behavior during fault conditions. In applications with sensitive detection circuits or low-impedance paths, the lower post-trip resistance of the RUE800 and 30R800UH may be preferred. For general protection applications, both specifications are functionally equivalent.

Q: Is the RUEF800 suitable for applications requiring higher current margins?

A: The RUEF800 is rated for 100A maximum current compared to 40A for other parts. This higher rating does not affect the 8A hold current or 16A trip current specifications. The RUEF800 is suitable for applications where transient currents may exceed 40A without affecting the fuse's primary protection function.

Q: Are there PCB layout considerations when substituting these parts?

A: Lead spacing is 0.402" (10.20mm) for RUE800, 30R800UH, MF-R800, and PFRA.800. The RUEF800 has 0.400" (10.15mm) spacing, a 0.05mm difference that does not require PCB redesign for standard through-hole applications. Physical length and height variations are minor and do not affect mounting compatibility.

Q: Which substitute part offers the best compliance coverage?

A: The RUEF800 carries the broadest certification coverage with CQC, CSA, TUV, and UL approvals. All substitute parts are RoHS3 compliant and REACH unaffected. Selection should align with specific regulatory requirements for the target application and market.