ST1R020B

Overview

The ST1R020B is an inrush current limiter (ICL) manufactured by Littelfuse Inc. It features a nominal resistance of 1 Ohm with a tolerance of ±15% at 25°C. The device supports a maximum steady-state current of 20 A and has a body length of 1.201 inches (30.50 mm). Lead spacing is specified at 0.310 inches (7.87 mm). This component belongs to the category of circuit protection devices designed for managing initial power surge currents.

Feature Summary

• Provides inrush current limiting functionality
• Utilizes positive temperature coefficient characteristics
• Designed for axial lead mounting configurations

Applications

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

Procurement Notes

Verify the specific Littelfuse datasheet for thermal derating curves and reset time specifications. Confirm that the 20 A rating aligns with your system's continuous operating requirements. Ensure the 1 Ohm resistance value meets the voltage drop constraints of your design. Check moisture sensitivity level classifications if surface mount alternatives are considered later.

Selection Notes

Select this component when managing high initial surge currents is critical for protecting downstream sensitive electronics. The 1 Ohm resistance offers a balance between effective current limiting and minimal steady-state power loss. Consider the physical dimensions of 30.50 mm for PCB layout clearance. Evaluate the thermal environment to ensure reliable operation within the rated 20 A limit.

Part Context

This part is categorized under Littelfuse's circuit protection portfolio, specifically within inrush current limiters. It serves as a passive component to mitigate electrical stress during power-up phases. The product line focuses on enhancing reliability in electronic systems by controlling transient currents without requiring active control logic.

Replacement Considerations

Consult official Littelfuse documentation for direct cross-reference part numbers. Verify compatibility regarding resistance values, current ratings, and physical footprint before substitution.