ST5R005B

Overview

The ST5R005B is a radial lead inrush current limiter (ICL) manufactured by Littelfuse Inc. This component functions as a thermistor designed to restrict high initial current during power-up phases. It features a nominal resistance of 5 Ohms with a tolerance of ±20%. The device supports a maximum steady-state current of 5 Amperes and has a physical diameter of 17.14 mm (0.675 inches). These specifications define its electrical and dimensional parameters for circuit protection applications.

Feature Summary

• Thermistor-based construction for automatic inrush current limitation
• Radial lead configuration for through-hole mounting
• Designed to protect sensitive components from startup surge currents

Applications

• Power supply input stages
• Transformer primary circuits
• Capacitive load protection

Procurement Notes

Verify the specific Littelfuse part number against official distributor catalogs to confirm availability, as this model may be classified as obsolete or end-of-life. Ensure that the replacement component matches the required 5 Ohm resistance and 5 A current rating. Cross-reference the package dimensions and lead spacing to guarantee mechanical compatibility with existing PCB layouts before finalizing procurement orders.

Selection Notes

Select this component when designing circuits requiring passive inrush current control without active switching elements. The 5 Ohm resistance value must align with the system's voltage drop requirements during startup. Consider the thermal dissipation capabilities and ambient operating temperature range to ensure reliable performance under continuous load conditions while maintaining effective surge suppression.

Part Context

This component belongs to the ST series of inrush current limiters produced by Littelfuse Inc. The series utilizes positive temperature coefficient thermistors to provide non-linear resistance characteristics. These devices are engineered for general-purpose circuit protection, offering a cost-effective solution for managing transient currents in various electronic assemblies compared to more complex active limiting solutions.

Replacement Considerations

Public confirmed substitute part numbers: None available.