72R040XU

Ptc Resettable Fuses Overview

The Littelfuse 72R040XU is a PolySwitch resettable PTC fuse designed for overcurrent protection. It features a radial leaded form factor suitable for PCB mounting. The device maintains a holding current of 400 mA and trips at 800 mA. It supports a maximum voltage of 72 VDC with a fault current rating of 40 A. Initial resistance is 550 mOhms minimum, rising to 1.29 Ohms maximum after tripping. Power dissipation is 560 mW. Operating temperature ranges from -40°C to +85°C. Dimensions are 7.6 mm diameter by 3.1 mm height.

Ptc Resettable Fuses Feature Summary

• Provides reliable overcurrent protection through polymer positive temperature coefficient technology
• Automatically resets to low resistance state after fault conditions clear
• Radial leaded construction facilitates through-hole PCB integration

Ptc Resettable Fuses Applications

• Circuit protection for automotive electronics
• Overcurrent safeguarding in telecom equipment
• Protection for power supply components

Ptc Resettable Fuses Procurement Notes

Verify the specific suffix against official Littelfuse documentation to confirm package type and reel specifications. Ensure the selected variant matches the required thermal and electrical ratings for the target application environment. Cross-reference part numbers with authorized distributors to confirm availability and authenticity.

Ptc Resettable Fuses Selection Notes

Select this component when a 400 mA holding current and 72 VDC rating align with circuit requirements. Consider the 1.29 Ohms trip resistance for voltage drop calculations. Evaluate the 560 mW power dissipation limit against ambient thermal conditions to ensure stable operation without nuisance tripping during normal load cycles.

Ptc Resettable Fuses Part Context

This device belongs to the 72R series of PolySwitch resettable fuses manufactured by Littelfuse. The series offers various current ratings and form factors including surface mount and radial leaded options. These components serve as reusable alternatives to traditional one-time fuses in electronic circuit protection designs.

Ptc Resettable Fuses Replacement Considerations

• RXEF040
• RXEF040-2
• RXEF040S
• RXEF040S-2

Ptc Resettable Fuses FAQ

What is the maximum fault current rating?

The maximum fault current rating is 40 A.

Does the device require replacement after a fault event?

No, it is a resettable fuse that returns to a low-resistance state once the fault is removed and the device cools down.