ST33001D

Overview

The ST33001D is an inrush current limiter (ICL) manufactured by Littelfuse Inc. It features a nominal resistance of 33 Ohms with a tolerance of ±20%. The device supports a maximum steady-state current of 500 mA and exhibits a hot resistance of 1.485 Ohms at rated current. The component has a cylindrical diameter of 0.449 inches (11.40 mm) and a lead spacing of 0.200 inches (5.08 mm). It complies with RoHS standards and is lead-free.

Feature Summary

• Provides inrush current limiting functionality to protect electronic circuits from high initial surge currents during power-up.
• Utilizes a thermistor-based design that automatically adjusts resistance based on temperature changes.
• Features a compact axial leaded package suitable for through-hole mounting on printed circuit boards.

Applications

• Power supply input stages
• Transformer protection circuits
• Motor drive inputs

Procurement Notes

Verify the specific Littelfuse datasheet revision for the ST33001D to confirm electrical characteristics and mechanical dimensions. Ensure compatibility with the target PCB layout regarding lead spacing and thermal requirements. Check for RoHS compliance documentation if required by project specifications. Confirm that the 500 mA steady-state current rating meets the application's operational needs without excessive self-heating.

Selection Notes

Select this component when a 33 Ohm initial resistance is required to limit inrush current effectively. Consider the 500 mA continuous current rating to ensure the device does not overheat during normal operation. Evaluate the physical size constraints, specifically the 11.40 mm diameter, to fit within the designated area on the circuit board. Assess the thermal environment to determine if additional cooling or spacing is necessary for reliable performance.

Part Context

The ST33001D belongs to the ST series of inrush current limiters produced by Littelfuse Inc. This series is designed for general-purpose circuit protection against surge currents. The part is commonly used in consumer electronics and industrial equipment where reliable power-up sequencing is critical. It serves as a passive component to enhance system longevity by reducing stress on downstream components.

Replacement Considerations

No public confirmed substitute part numbers are available in the provided documentation. Verify cross-reference options directly with Littelfuse technical support or authorized distributors for equivalent parts with matching electrical and mechanical specifications.