LITTELFUSE PolySwitch RUEF Series Resettable Fuse, 30V, 3A

The LITTELFUSE RUEF Series PolySwitch is a radial-leaded, resettable fuse (PPTC) that provides robust and reliable overcurrent protection for a wide array of modern electronic circuits. Engineered for a 30V voltage rating and holding currents up to 9A, this device represents one of the most comprehensive PPTC solutions available, designed for high-volume electronics assembly.

Its core function is to limit excessive current; in the event of an overcurrent fault, the device 'trips' into a high-resistance state, effectively breaking the circuit. Once the fault is cleared and power is cycled, it automatically resets, restoring normal operation. This eliminates the need for manual replacement, reducing maintenance costs and downtime. The RUEF300 variant features a 3.00A hold current (IH) and a 6.00A trip current (IT), with a maximum time to trip of 10.8 seconds at 15A.

Key Features & Construction

The fuse is constructed from cured, flame-retardant epoxy polymers that meet the stringent UL 94V-0 standard for insulating materials, ensuring safety and reliability. It offers a low initial resistance range of 0.020 to 0.050 ohms and is fitted with standard 24AWG leads for easy integration. With a compact rectangular form factor, it is suitable for space-constrained applications on PCBs.

Performance & Reliability

Capable of withstanding a maximum interrupt current (Imax) of 100A DC or 70A AC RMS, this fuse is built for demanding conditions. It operates reliably across an extensive temperature range from -40°C to +85°C, making it suitable for use in challenging environments. The typical power dissipation is 2.00W.

Versatile Applications

This PolySwitch device is ideal for protecting sensitive electronics in numerous sectors. Common applications include satellite video receivers, industrial control systems, computer motherboards, modems, and USB hubs. It is also perfectly suited for use