Is there a pin-compatible replacement for RUEF250?

Several parts like the RUEF300 share the same radial package and 2-pin layout. However, differences in hold current mean they are not drop-in replacements and require electrical validation.

What risks should I check before replacing RUEF250?

The main risk is using a fuse with a higher hold current (e.g., 4.0A or 5.0A), which may not protect your circuit from overcurrent events as intended. Always verify the hold and trip current of any replacement.

RUEF250 Alternatives, Datasheet & Cross Reference | Littelfuse

Finding a replacement for the RUEF250 PTC resettable fuse involves matching its 2.5A hold current, 30V rating, and radial package. Alternatives exist but require careful review of their current ratings to ensure proper circuit protection.

AI replacement insight

Electrical riskmedium

Hold/trip current differences require validation.

Package risklow

All viable candidates use the same radial package.

Sourcing risklow

Multiple alternatives from different manufacturers are available.

Can it be replaced directly?

No exact drop-in replacement is identified. The RUEF300 is the closest functional alternative but has a 20% higher hold current (3.0A vs 2.5A).

Best replacement path

The RUEF300 from the same Littelfuse series is the most promising path, with only a minor increase in hold current.

Main risk

The primary risk is compromised overcurrent protection from selecting a substitute with a significantly higher hold current.

Recommended alternatives

A resettable PTC fuse in a matching radial package with a slightly higher hold current of 3.0A.

View details

Alternative comparison matrix

Feature / factor	RUEF250	RUEF300	MF-R400	RUEF500	Compatibility / risk
Package	Radial	Radial	Radial	Radial	Radial — Form factor matches.; MF-R400: Form factor matches.; RUEF500: Form factor matches.
Voltage	30V	30V	30V	30V	30V — Voltage rating matches.; MF-R400: Voltage rating matches.; RUEF500: Voltage rating matches.
Current	2.5A	3.0A	4.0A	5.0A	3.0A / 4.0A / 5.0A — Slightly higher hold current may be acceptable.; MF-R400: Hold current is 60% higher, reducing protection sensitivity.; RUEF500: Hold current is 2x higher, significantly reducing protection sensitivity.
Resistance	0.040Ω	0.050Ω	-	-	0.050Ω — Max resistance is slightly higher.
Manufacturer	Littelfuse	-	BOURNS	-	BOURNS — Cross-vendor alternative.
Power	1.2W	-	-	3.0W	3.0W — Higher power dissipation.

Application & sourcing insights

Questions & answers

The Littelfuse RUEF300 is a strong candidate, offering the same package and voltage rating with a slightly higher 3.0A hold current. Engineering verification is advised to ensure it meets your protection needs.