ST2R503B

Overview

The ST2R503B is a negative temperature coefficient (NTC) thermistor inrush current limiter manufactured by Littelfuse Inc. Designed to mitigate high initial surge currents during circuit power-up, this component features a nominal resistance of 2.5 ohms with a tolerance of 20%. It supports a maximum steady-state current of 3A and utilizes a leaded package with a body diameter of 15.24mm. The device operates as a self-resetting protection element, transitioning from high resistance at cold start to low resistance during normal operation.

Feature Summary

• Reduces initial surge current when a circuit is powered on
• Functions as a self-resetting inrush current limiter
• Utilizes NTC thermistor technology for automatic resistance adjustment

Applications

• Power supply input stages
• Electronic equipment requiring surge protection
• Circuit protection systems

Procurement Notes

Verify the specific Littelfuse datasheet for precise thermal characteristics and derating curves. Confirm that the 3A steady-state current rating aligns with your application's operational requirements. Ensure the 15.24mm leaded form factor fits within your PCB layout constraints. Check regulatory compliance status such as RoHS if required for your manufacturing process.

Selection Notes

Select this component based on the required 2.5-ohm cold resistance to effectively limit inrush current for your specific load. Consider the 3A current handling capability to ensure safe operation under continuous load conditions. Evaluate the physical size of the 15.24mm body against available board space. Compare alternative NTC thermistors if different resistance values or package styles are necessary for the design.

Part Context

This part belongs to Littelfuse's range of inrush current limiters designed for circuit protection. These components are essential for safeguarding sensitive electronics from damage caused by high startup currents. The product line includes various thermistor types tailored for different current and resistance requirements across industrial and consumer applications.

Replacement Considerations

Public confirmed substitute part numbers are not provided in the available documentation. Consult Littelfuse technical resources for equivalent NTC thermistor alternatives with matching electrical specifications.