Is there a pin-compatible replacement for RUEF300?

Several PTC fuses share the RUEF300's 2-pin radial package, but key electricals like hold current differ. Pin compatibility does not guarantee a safe replacement.

What risks should I check before replacing RUEF300?

The main risk is using a fuse with a higher hold current (e.g., 4A or 5A), which will not protect a circuit designed for a 3A trip point, risking component damage.

RUEF300 Alternatives, Datasheet & Cross Reference | Littelfuse

Finding a substitute for the Littelfuse RUEF300 PTC fuse requires matching its 3A hold current and 30V rating. Alternatives often have different current ratings, impacting circuit protection.

AI replacement insight

Electrical riskhigh

Using a part with higher hold current will not protect the circuit as intended.

Package risklow

The radial leaded package is common and easy to match.

Can it be replaced directly?

No direct, drop-in replacement for the RUEF300 has been verified. All similar candidates have different current ratings, which impacts circuit protection.

Best replacement path

Search for a PTC resettable fuse with a 3A hold current, >=30V rating, and a compatible radial package. Prioritize matching hold and trip current.

Main risk

Electrical risk from mismatched hold/trip currents, leading to inadequate overcurrent protection.

Recommended alternatives

PTC resettable fuse with identical package and voltage, but a higher 4.0A hold current.

View details

Alternative comparison matrix

Feature / factor	RUEF300	MF-R400	RUEF500	Compatibility / risk
Package	Radial, 2-pin	Radial, 2-pin	Radial, 2-pin	Radial, 2-pin — Form factor matches.; RUEF500: Form factor matches.
Voltage	30V	30V	30V	30V — Voltage rating is identical.; RUEF500: Voltage rating is identical.
Current	3.0A	4.0A	5.0A	4.0A / 5.0A — Hold current is 33% higher, offers less protection.; RUEF500: Hold current is 67% higher, offers less protection.
Power	2.0W	2.5W	3.0W	2.5W / 3.0W — Higher power dissipation is acceptable.; RUEF500: Higher power dissipation is acceptable.

Application & sourcing insights

Questions & answers

No drop-in replacement is confirmed. Alternatives like Bourns MF-R400 have higher hold currents (4A) and require engineering review to ensure circuit safety.