BC850 NPN Transistor Technical Summary

Overview

The BC850 is a general-purpose NPN bipolar junction transistor (BJT) housed in a compact SOT323 plastic package. Designed for low-power applications, this transistor is optimized for low current and low voltage operations, making it suitable for a variety of amplification and switching tasks in electronic circuits. Its small form factor and reliable performance make it a popular choice for space-constrained designs.

Features

• Low Current Operation: Maximum collector current (Ic) of 100 mA, ideal for low-power applications.
• Low Voltage Rating: Maximum collector-emitter voltage (V_CEO) of 45 V, suitable for low-voltage circuits.
• Compact Package: SOT323 surface-mount package enables high-density PCB designs.
• High Current Gain (h_FE): Provides good amplification characteristics for signal processing.
• Low Noise: Suitable for audio and RF applications where signal integrity is critical.
• RoHS Compliant: Meets environmental standards for lead-free manufacturing.

Applications

The BC850 transistor is versatile and finds use in a broad range of electronic applications, including:

• Signal Amplification: Used in audio preamplifiers, RF stages, and sensor interfaces.
• Switching Circuits: Functions as a switch in low-power digital and analog circuits.
• Oscillators: Employed in LC and RC oscillator designs for clock generation.
• Driver Stages: Drives small relays, LEDs, and other low-current loads.
• Consumer Electronics: Found in portable devices, remote controls, and battery-operated gadgets.
• Telecommunication: Used in low-noise amplification stages for communication systems.

Electrical Characteristics

The following table summarizes the key electrical parameters of the BC850 transistor under standard test conditions (unless otherwise specified):

Absolute Maximum Ratings

• Collector-Emitter Voltage (V_CEO): 45 V
• Collector-Base Voltage (V_CBO): 50 V
• Emitter-Base Voltage (V_EBO): 5 V
• Collector Current (I_C): 100 mA
• Total Power Dissipation (P_tot): 250 mW
• Operating Junction Temperature (T_j): -55°C to +150°C
• Storage Temperature (T_stg): -55°C to +150°C

Typical Electrical Characteristics (T_A = 25°C)

• DC Current Gain (h_FE): 110 - 800 (at I_C = 2 mA, V_CE = 5 V)
• Collector-Emitter Saturation Voltage (V_CE(sat)): 0.25 V (max) (at I_C = 10 mA, I_B = 1 mA)
• Base-Emitter Saturation Voltage (V_BE(sat)): 0.9 V (max) (at I_C = 10 mA, I_B = 1 mA)
• Transition Frequency (f_T): 100 MHz (min) (at I_C = 10 mA, V_CE = 5 V)
• Noise Figure (NF): 5 dB (typical) (at f = 1 kHz, I_C = 100 µA, V_CE = 5 V)

Package Information

The BC850 is available in a SOT323 (SC-70) surface-mount package, which is designed for automated assembly processes. The package dimensions and pin configuration are as follows:

SOT323 Package Dimensions

• Package Type: SOT323 (SC-70)
• Body Size: 2.0 mm x 1.25 mm x 0.95 mm (L x W x H)
• Lead Pitch: 1.0 mm
• Pin Count: 3

Pin Configuration

• Pin 1 (Emitter): Connected to the emitter terminal of the transistor.
• Pin 2 (Base): Connected to the base terminal for biasing control.
• Pin 3 (Collector): Connected to the collector terminal, the primary output.

Thermal Characteristics

• Thermal Resistance, Junction-to-Ambient (R_θJA): 357°C/W
• Thermal Resistance, Junction-to-Lead (R_θJL): 125°C/W

Reliability and Compliance

The BC850 transistor is manufactured using high-reliability processes and adheres to industry standards for quality and performance. It is RoHS compliant, ensuring it meets environmental regulations for hazardous substance restrictions.

Conclusion

The BC850 NPN transistor is a reliable and versatile component for low-power amplification and switching applications. Its compact SOT323 package, combined with robust electrical characteristics, makes it an excellent choice for modern electronic designs where space and efficiency are critical. Whether used in consumer electronics, telecommunications, or industrial control systems, the BC850 delivers consistent performance under a wide range of operating conditions.