STMicroelectronics

BC817-40

BC817-40 Description

The BC817-40 from STMicroelectronics is an NPN bipolar junction transistor (BJT) designed for general-purpose amplification and switching applications. Packaged in a compact SOT-23 surface-mount form factor, it offers a collector-emitter breakdown voltage (VCEO) of 45V and a maximum collector current (Ic) of 500mA, making it suitable for low-to-medium power circuits. With a transition frequency (fT) of 100MHz, it delivers reliable high-frequency performance. The device operates within a junction temperature (TJ) range of up to 150°C and features a low VCE saturation voltage of 700mV @ 500mA, ensuring efficient switching.

BC817-40 Features

• High Current Gain (hFE): 250 (min) @ 100mA, 1V, ensuring strong signal amplification.
• Low Leakage Current: 100nA (ICBO) max, enhancing power efficiency.
• Compact & Reliable: SOT-23 package with MSL 1 (unlimited) moisture sensitivity, ideal for automated assembly.
• RoHS3 & REACH Compliant: Meets environmental and safety standards.
• Optimized for Switching: Low saturation voltage (700mV @ 500mA) minimizes power loss.
• Wide Operating Temperature: -55°C to +150°C (TJ), suitable for harsh environments.

BC817-40 Applications

• Signal Amplification: Audio preamps, sensor interfaces, and RF stages.
• Switching Circuits: Relay drivers, LED drivers, and load switches.
• Power Management: DC-DC converters, voltage regulators, and battery-powered systems.
• Portable Electronics: Smartphones, wearables, and IoT devices due to its small footprint.
• Automotive & Industrial: Robust performance under high-temperature conditions.

Conclusion of BC817-40

The BC817-40 stands out as a versatile, high-performance NPN transistor, combining high current gain, low saturation voltage, and compact packaging. Its 45V breakdown voltage and 500mA current handling make it ideal for both analog and digital applications. While marked as obsolete, it remains a reliable choice for legacy designs or replacements. Engineers favor it for its efficiency in switching and amplification, particularly in space-constrained or temperature-sensitive environments. For modern alternatives, consider checking STMicroelectronics' updated BJT portfolio while leveraging this model's proven reliability.