Infineon Technologies

BC857B  

Single Bipolar Transistors

BC857B Description

The BC857B from Infineon Technologies is a PNP bipolar junction transistor (BJT) designed for general-purpose amplification and switching applications. Encased in a compact SOT23-3 surface-mount package, 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 delivers reliable high-frequency performance. The transistor operates within a junction temperature (TJ) range of up to 150°C, ensuring stability in demanding environments. Although marked as obsolete, it remains a viable choice for legacy designs due to its high DC current gain (hFE ≥ 220 @ 2mA, 5V) and low saturation voltage (650mV @ 5mA, 100mA).

BC857B Features

• High Voltage Tolerance: 45V Vce breakdown voltage for robust performance in low-voltage circuits.
• Low Leakage Current: 15nA (ICBO) cutoff current minimizes power loss in standby modes.
• Optimized Gain: hFE ≥ 220 ensures efficient signal amplification.
• Compact & RoHS Compliant: SOT23-3 package saves board space while meeting environmental standards.
• Low Saturation Voltage: 650mV @ 100mA enhances efficiency in switching applications.
• Wide Temperature Range: Operates reliably up to 150°C TJ.

BC857B Applications

Ideal for:

• Signal amplification in audio and RF stages.
• Load switching in portable electronics (e.g., sensors, IoT devices).
• Interface circuits requiring low saturation voltage.
• Driver stages for relays or LEDs in automotive/industrial systems.
• Legacy designs where high gain and low leakage are critical.

Conclusion of BC857B

The BC857B is a versatile PNP transistor offering balanced performance in amplification and switching roles. Its high gain, low saturation voltage, and compact form factor make it a pragmatic choice for space-constrained, low-power designs. While obsolete, its reliability and compliance with RoHS3 ensure continued relevance in maintenance cycles and niche applications. Engineers valuing cost-effective, proven solutions may still find it advantageous for specific use cases.

BC857B Documents

Download datasheets and manufacturer documentation for BC857B

Datasheets :

BC857B