ST1R005B

Overview

The ST1R005B is a radial lead inrush current limiter (ICL) manufactured by Littelfuse Inc. This component features a nominal resistance of 1 Ohm with a tolerance of ±30%. It is rated for a maximum steady-state current of 5 Amperes and has a body diameter of 12.95 mm (0.510 inches). The device is designed to limit initial surge currents during power-up sequences, protecting downstream electronic components from thermal stress. This specific part number is currently listed as no longer manufactured.

Feature Summary

• Provides high initial resistance to restrict inrush current flow upon circuit energization
• Automatically reduces resistance as the device heats up during normal operation
• Radial leaded package design facilitates through-hole mounting on printed circuit boards

Applications

• Power supply input stages
• Transformer primary windings
• Capacitor bank charging circuits

Procurement Notes

Verify availability status carefully as this component is marked as obsolete or non-manufactured. Sourcing may require checking secondary market distributors or surplus inventory holders. Confirm that the replacement strategy accounts for the end-of-life status to ensure long-term supply chain stability for production runs.

Selection Notes

Select based on required steady-state current handling and initial resistance values. Ensure the physical dimensions fit the available board space. Consider thermal derating requirements for ambient operating temperatures. Evaluate if resettable behavior aligns with system restart protocols and fault recovery needs.

Part Context

This component belongs to the ST series of inrush current limiters from Littelfuse. These devices utilize positive temperature coefficient materials to dynamically adjust resistance. The series offers various resistance and current ratings to suit different power levels and surge protection requirements across industrial and consumer electronics.

Replacement Considerations

Consult official Littelfuse documentation for direct cross-reference substitutes. Verify that any alternative ICL matches the 1 Ohm nominal resistance, 5A current rating, and 12.95mm diameter constraints to maintain circuit performance and mechanical fit.