BD433S

Overview

The BD433S is a medium power NPN epitaxial silicon transistor manufactured by Fairchild Semiconductor. It features a collector-emitter voltage rating of 22 V and a continuous collector current capacity of 4 A. The device is designed for through-hole mounting in the TO-126-3 package, which supports a maximum power dissipation of 36 W. Key electrical specifications include a transition frequency of 3 MHz and a DC current gain suitable for general-purpose amplification and switching applications.

Feature Summary

• NPN epitaxial silicon construction for reliable medium-power operation
• High current handling capability with 4 A continuous collector current
• Through-hole TO-126-3 package design for robust thermal management

Applications

• General-purpose linear amplification circuits
• Medium-power switching applications
• Audio amplifier output stages

Procurement Notes

Verify component authenticity as this part is discontinued by Fairchild Semiconductor. Sourcing from authorized distributors or certified surplus suppliers is recommended to ensure reliability. Check datasheet revisions and manufacturing dates carefully, as obsolete components may have varying quality standards depending on the production batch and storage history.

Selection Notes

Select the BD433S when a medium-power NPN transistor with 22 V breakdown and 4 A current capacity is required in a TO-126 package. Ensure thermal management strategies account for the 36 W power dissipation limit. Consider availability constraints due to discontinuation status and evaluate alternative equivalents if long-term supply stability is critical for the design.

Part Context

The BD433S belongs to the family of medium-power NPN transistors produced by Fairchild Semiconductor. It is an obsolete component no longer in active production. The TO-126-3 package provides a balance of power handling and ease of integration for legacy and specific industrial designs requiring through-hole mounting solutions.

Replacement Considerations

Public confirmed substitute part numbers are not available in the provided documentation. Due to the discontinued status, engineers should consult manufacturer cross-reference guides or equivalent generic NPN transistor specifications matching 22 V, 4 A, and TO-126 requirements.