BCY59VIII

Overview

The BCY59VIII is an NPN silicon epitaxial planar transistor manufactured by STMicroelectronics, designed for general-purpose switching and amplification applications. It is housed in a TO-18 metal can package, providing robust mechanical stability and thermal performance. The device features a collector-emitter breakdown voltage of 45 V and a continuous collector current rating of 200 mA. With a transition frequency of 200 MHz and a maximum power dissipation of 390 mW at 25°C ambient temperature, it supports high-frequency operations. The component operates within a junction temperature range up to 175°C and exhibits a DC current gain (hFE) of at least 180 under specified test conditions.

Feature Summary

• NPN epitaxial planar construction for reliable switching performance
• TO-18 metal can package offering high thermal resistance and durability
• High transition frequency suitable for RF and audio amplifier stages
• Extended operating junction temperature capability

Applications

• General-purpose low-power switching circuits
• Audio frequency amplification stages
• Radio frequency signal processing
• Driver circuits for small loads

Procurement Notes

Verify the specific suffix VIII against the manufacturer's official datasheet to confirm pinout compatibility and electrical tolerances. Ensure the component meets RoHS 3 compliance requirements if applicable to your assembly process. Check for obsolescence status as legacy through-hole components may have limited availability from primary sources.

Selection Notes

Select this component when a hermetically sealed metal package is required for harsh environments or high reliability. Compare the 45V breakdown and 200mA current limits against circuit demands to ensure adequate headroom. Consider the TO-18 footprint constraints during PCB layout planning compared to modern plastic surface-mount alternatives.

Part Context

This part belongs to the BCY59 family of NPN switching transistors produced by STMicroelectronics. It serves as a discrete semiconductor solution for analog and digital switching tasks. The TO-18 package distinguishes it from modern SMD variants, targeting applications where leaded mounting and metal casing provide necessary shielding or heat sinking benefits.

Replacement Considerations

Direct replacements include the BCY59VII or generic equivalents like 2N3904 if voltage and current ratings align with system requirements. Verify that substitute parts match the TO-18 package dimensions and pin configuration to ensure physical compatibility without redesigning the host board.