RXE040 Equivalent & Substitute Parts

Part Overview

The RXE040 is a polymeric PTC resettable fuse manufactured by Littelfuse Inc., rated for 72V maximum voltage and 400 mA hold current. This component is classified as obsolete, making equivalent and substitute parts necessary for ongoing system support and new designs. The RXE040 belongs to the PolySwitch® RXE series and is designed for through-hole radial mounting in disc configuration.

Substiute Parts

RXE040

Littelfuse Inc.In Stock: 940RXE040 Datasheet

Current PartRFQ

RXEF040

LittelfuseIn Stock: 2349RXEF040 Datasheet

DirectRFQ

60R040XU

Littelfuse Inc.In Stock: 103460R040XU Datasheet

MFR RecommendedRFQ

0ZRC0040FF1E

Bel Fuse Inc.In Stock: 55930ZRC0040FF1E Datasheet

DirectRFQ

MF-R040

Bourns Inc.In Stock: 11844MF-R040 Datasheet

DirectRFQ

PFRA.040

SCHURTER Inc.In Stock: 1111PFRA.040 Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution for the RXE040 is determined by the following critical parameters:

• Voltage rating must equal or exceed 72V maximum
• Current hold (Ih) must equal 400 mA
• Current trip (It) must equal 800 mA
• Time to trip must equal 3.8 s
• Resistance characteristics (Ri and R1) must match specified ranges
• Mounting type must be through-hole radial disc configuration
• Lead spacing must be compatible with 0.199" (5.05mm) or equivalent mechanical footprint

Substitute parts are grouped into two categories:

Direct Equivalents: Parts meeting all electrical and mechanical parameters with identical or superior voltage ratings and active product status.

Functional Alternatives: Parts with voltage ratings below 72V (60V) that maintain all other electrical characteristics and mechanical compatibility, suitable for applications where the actual operating voltage is lower than the RXE040 maximum rating.

Parameter Comparison

Engineering Selection Recommendations

Primary Recommendation: RXEF040

The RXEF040 is the direct equivalent to the obsolete RXE040. It maintains identical electrical specifications (72V, 400 mA hold current, 3.8 s trip time) and mechanical configuration. The RXEF040 is active product status with ROHS3 compliance and expanded approval agency certifications (CQC, CSA, TUV, UL). This part provides the most direct replacement path with no design modifications required.

Secondary Recommendation: 0ZRC0040FF1E

The 0ZRC0040FF1E from Bel Fuse Inc. exceeds the voltage rating at 90V while maintaining all other electrical parameters. This part is active with AEC-Q200 rating and ROHS3 compliance. The lead spacing tolerance (0.201" vs. 0.199") requires verification for PCB footprint compatibility. This option provides enhanced voltage margin for applications requiring additional safety headroom.

Functional Alternatives: 60R040XU, MF-R040, PFRA.040

These parts operate at 60V maximum voltage, which is 12V below the RXE040 specification. They are suitable only for applications where the actual operating voltage does not exceed 60V. All three maintain the 400 mA hold current, 800 mA trip current, and 3.8 s trip time. Lead spacing is 0.201" (5.10mm), requiring PCB footprint verification. All three are active products with ROHS3 compliance.

Frequently Asked Questions (FAQ)

Q: Can the RXEF040 be used as a direct replacement for RXE040?

A: Yes. The RXEF040 is electrically and mechanically equivalent to the RXE040, with identical voltage (72V), hold current (400 mA), trip current (800 mA), and trip time (3.8 s). The RXEF040 is active product status, making it the recommended replacement for obsolete RXE040 applications.

Q: What is the difference between the 72V-rated parts and the 60V-rated parts?

A: The 72V-rated parts (RXEF040, 0ZRC0040FF1E) maintain the original RXE040 voltage specification. The 60V-rated parts (60R040XU, MF-R040, PFRA.040) have a lower maximum voltage rating. Selection depends on the actual operating voltage in your application. If the circuit operates below 60V, the lower-rated parts are acceptable. If the circuit operates between 60V and 72V, only the 72V-rated parts are suitable.

Q: Are there mechanical compatibility concerns with substitute parts?

A: Lead spacing differs slightly between parts. The RXE040 and RXEF040 specify 0.199" (5.05mm) lead spacing, while 60R040XU, 0ZRC0040FF1E, MF-R040, and PFRA.040 specify 0.201" (5.10mm). Verify PCB footprint dimensions before substitution. The radial disc package configuration is consistent across all parts.

Q: Which substitute part has the best compliance certifications?

A: The RXEF040 carries the broadest approval agency coverage (CQC, CSA, TUV, UL) and ROHS3 compliance. The 0ZRC0040FF1E includes AEC-Q200 automotive qualification. The 60R040XU, MF-R040, and PFRA.040 carry cURus and TUV certifications with ROHS3 compliance.

Q: Can I use the 0ZRC0040FF1E if my application requires 72V operation?

A: Yes. The 0ZRC0040FF1E is rated for 90V maximum voltage, which exceeds the 72V requirement. All other electrical parameters (400 mA hold current, 800 mA trip current, 3.8 s trip time) match the RXE040 specification. Verify lead spacing compatibility (0.201" vs. 0.199") with your PCB design.

Q: What is the difference in initial resistance between parts?

A: Most substitute parts specify 550 mOhms minimum initial resistance, matching the RXE040. The MF-R040 and PFRA.040 specify 520 mOhms minimum, which is within acceptable tolerance for this component category. Post-trip resistance (R1) is 1.29 Ohms maximum across all parts.