The BC856 is an industry-standard general-purpose PNP bipolar junction transistor (BJT) housed in a compact SOT-23 surface-mount package. Designed for low-noise, high-voltage switching and linear amplification applications, the BC856 is the PNP complement to the BC846. Featuring a high collector-emitter breakdown voltage of -65V, reliable current gain linearity, and fast switching capability, it is widely utilized in high-side load switching, level translation, audio preamplifier stages, and general discrete analog circuitry.

Specifications

• Brand / Manufacturer: Nexperia / ON Semiconductor / Diodes Inc. / Industry Standard
• Part Number / Marking: BC856 (Common Markings: 3A, 3B, 3D depending on gain grade)
• Transistor Type: PNP Bipolar Junction Transistor (BJT)
• Collector-Emitter Voltage (V_CEO): -65V
• Collector-Base Voltage (V_CBO): -80V
• Emitter-Base Voltage (V_EBO): -5V to -6V
• Continuous Collector Current (I_C): -100mA
• Peak Collector Current (I_CM): -200mA
• DC Current Gain (h_FE): 110 to 800 (BC856A: 110–220, BC856B: 200–450 @ I_C = -2mA, V_CE = -5V)
• Transition Frequency (f_T): 100 MHz (Minimum) / 250 MHz (Typical)
• Collector-Emitter Saturation Voltage (V_CE(sat)): < -300mV @ I_C = -10mA, I_B = -0.5mA / < -650mV @ I_C = -100mA, I_B = -5mA
• Total Power Dissipation (P_tot): 250mW to 300mW (at T_amb = 25°C)
• Operating Junction Temperature: -65°C to +150°C
• Package / Case: SOT-23 (TO-236AB) Surface Mount (Pin 1: Base, Pin 2: Emitter, Pin 3: Collector)

Features

• High Voltage Rating: Withstands collector-emitter voltages up to -65V, making it ideal for industrial 24V/48V control lines and telecom circuits.
• Low Noise Amplification: Offers low-noise characteristics, making it suitable for front-end audio preamplifiers and sensitive analog sensor conditioning.
• Excellent Current Gain Linearity: Maintains stable h_FE across a wide operating current range for predictable linear gain performance.
• PNP Complement to BC846: Pairs perfectly with the BC846 NPN transistor for push-pull output stages, complementary amplifiers, and H-bridge drive networks.
• Miniature Surface-Mount Footprint: Compact SOT-23 casing saves valuable board real estate in high-density automated SMT production.

Common Applications

• High-Side Switching: Gating sub-circuits, indicator LEDs, buzzers, and small relays from the positive power rail.
• Audio Preamplifier Stages: Low-noise discrete preamplification and input buffer stages.
• Push-Pull Output Stages: Complementary Class-AB audio amplifiers paired with the BC846 NPN transistor.
• Level Shifting & Inversion: Converting control logic signals between different voltage domains.
• Current Mirrors & Constant Current Sources: Building precision active current sources and dynamic loads in analog circuits.

Usage Tips

• High-Side Configuration: Connect the Emitter (Pin 2) to the positive supply voltage (V_CC) and the Collector (Pin 3) to the load. Pulling the Base (Pin 1) low (towards GND) turns the transistor ON.
• Base Current Limiting: Always include a series base resistor (R_B) sized to ensure sufficient base current (I_B ≈ I_C / 10 to I_C / 20) for full saturation when used as a switch.
• Base Pull-Up Resistor: Place a 10kΩ to 100kΩ pull-up resistor between the Base and Emitter (V_CC) to guarantee the transistor remains fully OFF during microcontroller power-up or high-impedance states.
• Inductive Kickback Protection: When driving inductive components such as relay coils, always place a flyback diode across the load to protect against high reverse-voltage inductive spikes.

Datasheet