RXEF375-2 Polymeric PTC Resettable Fuse Equivalent & Substitute Parts

Part Overview

The RXEF375-2 is a polymeric PTC resettable fuse manufactured by Littelfuse, rated for 72V maximum voltage with a 3.75A hold current. This component is classified as obsolete, which necessitates identification of active equivalent alternatives for continued circuit protection applications. The part functions as a self-resetting overcurrent protection device suitable for through-hole radial mounting in electronic assemblies requiring thermal and electrical fault protection.

Key Parameters

Parameter	Value
Voltage - Max	72V
Current - Hold (Ih) (Max)	3.75 A
Current - Trip (It)	7.5 A
Current - Max	40 A
Time to Trip	24 s
Resistance - Initial (Ri) (Min)	30 mOhms
Resistance - Post Trip (R1) (Max)	80 mOhms
Operating Temperature	-40°C ~ 85°C
Mounting Type	Through Hole
Package / Case	Radial, Disc

Substitute Part Grouping Explanation

Substitution eligibility for the RXEF375-2 is determined by strict equivalence across the following critical parameters:

Voltage rating: 72V maximum
Current hold specification: 3.75A
Current trip specification: 7.5A
Resistance characteristics: Initial minimum 30 mOhms, post-trip maximum 80 mOhms
Mounting configuration: Through-hole radial disc package
Operating temperature range: -40°C to 85°C

Both identified substitute parts meet these electrical and mechanical requirements without deviation. Substitution is valid based on functional equivalence within the specified parameter envelope.

Parameter Comparison

Parameter	RXEF375-2 (Main)	72R375XH (Substitute)	RXEF375 (Substitute)
Manufacturer	Littelfuse	Littelfuse Inc.	Littelfuse
Series	PolySwitch®, RXEF	POLY-FUSE®, 72R	PolySwitch®, RXEF
Product Status	Obsolete	Active	Active
Voltage - Max	72V	72V	72V
Current - Hold (Ih) (Max)	3.75 A	3.75 A	3.75 A
Current - Trip (It)	7.5 A	7.5 A	7.5 A
Current - Max	40 A	40 A	40 A
Time to Trip	24 s	24 s	24 s
Resistance - Initial (Ri) (Min)	30 mOhms	30 mOhms	30 mOhms
Resistance - Post Trip (R1) (Max)	80 mOhms	80 mOhms	80 mOhms
Operating Temperature	-40°C ~ 85°C	-40°C ~ 85°C	-40°C ~ 85°C
Mounting Type	Through Hole	Through Hole	Through Hole
Package / Case	Radial, Disc	Radial, Disc	Radial, Disc
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
REACH Status	REACH Unaffected	REACH Unaffected	REACH Unaffected
Approval Agency	CQC, CSA, TUV, UL	cURus, TUV	CQC, CSA, TUV, UL

Engineering Selection Recommendations

Both substitute parts are functionally equivalent to the obsolete RXEF375-2 based on electrical and mechanical parameter alignment.

The RXEF375 is the manufacturer-recommended replacement, maintaining identical physical dimensions (1.071" Dia x 0.118" T), lead spacing (0.400"), and approval certifications (CQC, CSA, TUV, UL). This part carries active product status and is available in bag packaging.

The 72R375XH provides an alternative from the POLY-FUSE® series with marginally different physical dimensions (1.035" Dia x 0.122" T) and lead spacing (0.402"), within tolerance for standard through-hole mounting. This part is active and available in bulk packaging. Approval certifications include cURus and TUV.

Selection between these substitutes should be based on packaging requirements, inventory availability, and specific certification needs for the target application.

Frequently Asked Questions (FAQ)

Q: Can RXEF375-2 be directly replaced with RXEF375?

A: Yes. The RXEF375 is the manufacturer-recommended active equivalent with identical electrical specifications, operating temperature range, and approval certifications. Physical dimensions and lead spacing are identical.

Q: What are the differences between 72R375XH and RXEF375?

A: Both parts meet the electrical requirements for substitution. The 72R375XH has slightly different physical dimensions (1.035" Dia x 0.122" T versus 1.071" Dia x 0.118" T) and lead spacing (0.402" versus 0.400"). The 72R375XH carries cURus and TUV certifications, while RXEF375 includes CQC, CSA, TUV, and UL certifications.

Q: Are there mechanical compatibility concerns with the 72R375XH?

A: The dimensional differences in the 72R375XH are minor and fall within standard through-hole mounting tolerances. Lead spacing variation of 0.002" is negligible for PCB hole patterns designed for radial disc fuses.

Q: Do all substitute parts meet RoHS and REACH compliance?

A: Yes. All three parts are ROHS3 compliant and REACH unaffected.

Q: What is the difference between bag and bulk packaging?

A: Packaging format does not affect electrical or mechanical performance. Selection depends on procurement quantity requirements and inventory management practices.

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