The BD170S is a silicon NPN epitaxial planar transistor from Freescale Semiconductor (now NXP). It's designed for use in a variety of general-purpose amplifier and switching applications. This transistor is known for its robust characteristics and reliability in various electronic circuits.

Applications:

• General-purpose amplification
• Switching circuits
• Audio amplifiers
• Power supplies
• Driver stages in electronic circuits

Features:

• NPN Epitaxial Planar Transistor
• High Collector-Emitter Voltage (VCEO)
• High Collector Current (IC)
• Low Saturation Voltage
• High Transition Frequency (fT)

Benefits:

• Provides reliable amplification in various circuits.
• Efficient switching capabilities for power control.
• Suitable for both low and medium power applications.
• Easy to integrate into existing circuit designs.
• Offers a cost-effective solution for general-purpose transistor needs.

Additional Details:

The BD170S is typically available in a TO-126 package. Key specifications include a Collector-Emitter Voltage (VCEO) of around 60V, a Collector Current (IC) of approximately 2A, and a power dissipation of about 12.5W. The transition frequency (fT) is typically around 50 MHz, making it suitable for audio and other medium-frequency applications. It's designed to operate over a wide temperature range.

This transistor is commonly used in linear power supplies as a series regulator pass element. It’s also employed as a driver for higher-power transistors in audio amplifiers. Its robust design ensures a long operational life and stable performance in demanding environments. Proper heat sinking is recommended for applications with higher power dissipation to ensure that the maximum junction temperature is not exceeded.