RUEF250-1 Polymeric PTC Resettable Fuse Equivalent & Substitute Parts

Part Overview

The RUEF250-1 is a polymeric PTC resettable fuse manufactured by Littelfuse Inc. in the PolySwitch® RUEF series. This component is rated for 30V maximum voltage with a 2.5A hold current and is designed for through-hole radial mounting in disc configuration. The part is currently listed as obsolete, making identification of active equivalent and substitute parts essential for ongoing design support and procurement.

Key Parameters

Parameter	Value
Voltage - Max	30V
Current - Hold (Ih) (Max)	2.5 A
Current - Trip (It)	5 A
Current - Max	100 A
Time to Trip	10.3 s
Resistance - Initial (Ri) (Min)	20 mOhms
Resistance - Post Trip (R1) (Max)	70 mOhms
Operating Temperature	-40°C ~ 85°C
Mounting Type	Through Hole
Package / Case	Radial, Disc
Size / Dimension	0.449" L x 0.118" W (11.40mm x 3.00mm)
Lead Spacing	0.199" (5.05mm)
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitution of the RUEF250-1 is determined by strict equivalence across the following critical parameters:

Voltage rating: 30V maximum
Hold current (Ih): 2.5A maximum
Trip current (It): 5A
Time to trip: 10.3 seconds
Initial resistance (Ri): 20 mOhms minimum
Post-trip resistance (R1): 70 mOhms maximum
Mounting configuration: Through-hole radial disc
Physical dimensions: 0.449" L x 0.118" W with 0.199" lead spacing
Regulatory compliance: ROHS3 compliant, UL/TUV/CSA approved

Two substitute parts meet these electrical and mechanical specifications. RUEF250 is the direct manufacturer equivalent from Littelfuse with active product status. FRU250-30F from RFE/Fuzetec provides cross-manufacturer compatibility with identical electrical performance and mechanical fit.

Parameter Comparison

Parameter	RUEF250-1 (Main)	RUEF250 (Substitute)	FRU250-30F (Substitute)
Manufacturer	Littelfuse Inc.	Littelfuse Inc.	RFE/Fuzetec
Product Status	Obsolete	Active	Active
Voltage - Max	30V	30V	30V
Current - Hold (Ih) (Max)	2.5 A	2.5 A	2.5 A
Current - Trip (It)	5 A	5 A	5 A
Current - Max	100 A	100 A	100 A
Time to Trip	10.3 s	10.3 s	10.3 s
Resistance - Initial (Ri) (Min)	20 mOhms	20 mOhms	20 mOhms
Resistance - Post Trip (R1) (Max)	70 mOhms	70 mOhms	70 mOhms
Operating Temperature	-40°C ~ 85°C	Not specified	-40°C ~ 85°C
Mounting Type	Through Hole	Through Hole	Through Hole
Package / Case	Radial, Disc	Radial, Disc	Radial, Disc
Size / Dimension	0.449" L x 0.118" W (11.40mm x 3.00mm)	0.449" L x 0.118" W (11.40mm x 3.00mm)	0.449" L x 0.118" W (11.40mm x 3.00mm)
Lead Spacing	0.199" (5.05mm)	0.199" (5.05mm)	0.201" (5.10mm)
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Approval Agency	CQC, CSA, TUV, UL	CQC, CSA, TUV, UL	cUL, TUV, UL

Engineering Selection Recommendations

RUEF250 is the primary substitute for RUEF250-1. Both components are manufactured by Littelfuse Inc., share identical electrical specifications, and maintain the same physical form factor. RUEF250 holds active product status, ensuring long-term availability and supply chain continuity. This part carries the same regulatory certifications (CQC, CSA, TUV, UL) and ROHS3 compliance as the original.

FRU250-30F from RFE/Fuzetec provides a secondary cross-manufacturer alternative. It delivers equivalent electrical performance across all critical parameters and maintains mechanical compatibility with a lead spacing of 0.201" (5.10mm), which is within acceptable tolerance of the original 0.199" (5.05mm) specification. FRU250-30F holds active product status and carries UL, cUL, and TUV certifications. The operating temperature range matches the original specification at -40°C to 85°C.

Both substitutes are ROHS3 compliant and REACH unaffected, meeting modern regulatory requirements. Selection between RUEF250 and FRU250-30F depends on procurement availability, cost considerations, and supply chain preferences.

Frequently Asked Questions (FAQ)

Q: Can RUEF250 be used as a direct replacement for RUEF250-1?

A: Yes. RUEF250 is electrically and mechanically equivalent to RUEF250-1. Both components share identical voltage ratings (30V), hold current (2.5A), trip current (5A), resistance specifications, and physical dimensions. The primary difference is product status: RUEF250-1 is obsolete while RUEF250 is active.

Q: What is the difference between RUEF250 and FRU250-30F?

A: Both parts meet identical electrical specifications for 30V, 2.5A hold current, and 5A trip current. The lead spacing differs slightly: RUEF250 has 0.199" (5.05mm) spacing while FRU250-30F has 0.201" (5.10mm) spacing. This 0.002" difference is within standard PCB tolerance for through-hole radial components. RUEF250 is manufactured by Littelfuse; FRU250-30F is manufactured by RFE/Fuzetec.

Q: Are there packaging differences between these substitutes?

A: Yes. RUEF250-1 and RUEF250 are available in different packaging formats (radial disc configuration). RUEF250 is supplied in bag packaging, while FRU250-30F is supplied in bulk packaging. The component form factor remains identical across all three parts.

Q: Do all three parts have the same regulatory certifications?

A: RUEF250-1 and RUEF250 carry CQC, CSA, TUV, and UL certifications. FRU250-30F carries cUL, TUV, and UL certifications. All three are ROHS3 compliant and REACH unaffected. Verify specific certification requirements for your application before final selection.

Q: What is the operating temperature range for each part?

A: RUEF250-1 and FRU250-30F both specify -40°C to 85°C operating temperature. RUEF250 does not specify an operating temperature range in available documentation. For applications requiring confirmed temperature specifications, RUEF250-1 or FRU250-30F are preferred.

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