RXEF040-AP Polymeric PTC Resettable Fuse - Equivalent & Substitute Parts

Part Overview

The RXEF040-AP is a polymeric PTC resettable fuse manufactured by Littelfuse Inc., part of the PolySwitch® RXEF series. This component is designed for overcurrent protection in electronic circuits operating at 72V with a 400 mA hold current. The device is currently in active production status with 1010 units available in inventory. Substitute parts are identified when electrical and mechanical parameters align within the specified tolerances for this product category, enabling direct replacement in circuit designs without functional degradation.

Substiute Parts

RXEF040-AP

Littelfuse Inc.In Stock: 1067RXEF040-AP Datasheet

Current PartRFQ

72R040XPR

LittelfuseIn Stock: 281872R040XPR Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

The 72R040XPR qualifies as a direct substitute for the RXEF040-AP based on the following critical parameters:

Electrical Equivalence:

• Identical maximum voltage rating: 72V
• Identical hold current (Ih): 400 mA
• Identical trip current (It): 800 mA
• Identical maximum current: 40 A
• Identical time to trip: 3.8 s
• Identical initial resistance (Ri): 550 mOhms minimum
• Identical post-trip resistance (R1): 1.29 Ohms maximum
• Identical operating temperature range: -40°C ~ 85°C

Mechanical Compatibility:

• Identical mounting type: Through Hole
• Identical package type: Radial, Disc
• Lead spacing within acceptable tolerance: 0.199" (5.05mm) vs. 0.201" (5.10mm)
• Physical dimensions compatible for PCB placement

Compliance Alignment:

• Both components are ROHS3 compliant
• Both rated for EAR99 export classification

Parameter Comparison

Engineering Selection Recommendations

Both the RXEF040-AP and 72R040XPR are active production components manufactured by Littelfuse Inc. with full ROHS3 compliance. The 72R040XPR represents the POLY-FUSE® series variant within the same manufacturer's portfolio, while the RXEF040-AP belongs to the PolySwitch® RXEF series. Selection between these parts should be based on:

Availability: The 72R040XPR currently has higher inventory availability (2727 units) compared to the RXEF040-AP (1010 units), making it suitable for high-volume production requirements.

Certification Scope: The RXEF040-AP carries approvals from CQC, CSA, TUV, and UL. The 72R040XPR carries cURus and TUV approvals. Verify that the required certification body for your application is present on the selected part.

Physical Dimensions: Lead spacing differs by 0.002" (0.05mm), which is negligible for standard PCB layouts. Both components maintain identical height and disc diameter specifications.

Both parts are suitable for direct substitution in 72V, 400 mA hold current applications requiring polymeric PTC resettable fuse protection.

Frequently Asked Questions (FAQ)

Q: Can the 72R040XPR replace the RXEF040-AP in existing designs?

A: Yes. All critical electrical parameters are identical, including voltage rating, hold current, trip current, and resistance specifications. The lead spacing difference of 0.002" is within standard PCB manufacturing tolerances and does not affect mechanical compatibility.

Q: Are there differences in approval certifications between these parts?

A: The RXEF040-AP carries CQC, CSA, TUV, and UL approvals. The 72R040XPR carries cURus and TUV approvals. Confirm that your application requirements are met by the certifications present on the selected part before implementation.

Q: What is the significance of the PolySwitch® versus POLY-FUSE® series designation?

A: Both designations refer to Littelfuse's polymeric PTC resettable fuse technology. The series name reflects different product lines within the manufacturer's portfolio, but the electrical and mechanical specifications provided determine functional equivalence.

Q: Are both parts RoHS compliant?

A: Yes. Both the RXEF040-AP and 72R040XPR are ROHS3 compliant and suitable for applications requiring RoHS certification.

Q: What is the lead spacing tolerance, and does it affect PCB design?

A: The RXEF040-AP has 0.199" (5.05mm) lead spacing, while the 72R040XPR has 0.201" (5.10mm) lead spacing. This 0.002" difference is within standard PCB manufacturing tolerances and does not require design modifications for typical through-hole applications.