Taiwan Semiconductor

BC857B

BC857B Description

The BC857B from Taiwan Semiconductor Corporation is a PNP bipolar junction transistor (BJT) housed in a compact SOT-23 surface-mount package. Designed for general-purpose amplification and switching applications, it offers a collector-emitter voltage (Vce) rating of -45V and a maximum collector current (Ic) of -100mA, making it suitable for low-power circuits. With a transition frequency (fT) of 100MHz, it ensures efficient high-frequency performance. The transistor exhibits a low Vce saturation voltage of 650mV @ 5mA, 100mA, minimizing power loss in switching applications. Its DC current gain (hFE) ranges from 220 @ 2mA, 5V, ensuring reliable signal amplification.

BC857B Features

• High Voltage Tolerance: Supports up to -45V Vce, ideal for circuits requiring moderate voltage handling.
• Low Saturation Voltage: 650mV @ 5mA, 100mA ensures energy-efficient switching.
• High Transition Frequency: 100MHz fT enables stable performance in RF and high-speed applications.
• Low Leakage Current: 100nA (ICBO) cutoff current minimizes power wastage.
• Compact & RoHS Compliant: SOT-23 package with ROHS3 compliance suits modern, eco-conscious designs.
• Reliable Gain: hFE of 220 @ 2mA, 5V guarantees consistent amplification.

BC857B Applications

The BC857B excels in:

• Signal Amplification: Audio preamps, sensor interfaces, and low-noise analog circuits.
• Switching Circuits: Load drivers, relay controllers, and low-power DC-DC converters.
• High-Frequency Systems: RF modules, oscillators, and communication devices (up to 100MHz).
• Portable Electronics: Battery-operated devices due to low leakage and saturation losses.
• Automotive & Industrial Systems: Robust performance in harsh environments (REACH unaffected).

Conclusion of BC857B

The BC857B stands out as a versatile, high-performance PNP transistor, combining low power dissipation, compact packaging, and reliable gain. Its 100MHz transition frequency and low saturation voltage make it superior to generic BJTs in high-speed or efficiency-critical designs. Whether for amplification, switching, or RF applications, this transistor delivers consistent performance, backed by Taiwan Semiconductor’s quality and ROHS3/REACH compliance. Ideal for engineers seeking a balance of cost, size, and functionality in modern electronics.