Infineon Technologies BC 857B B5003

Overview

BC857B from Nexperia is a PNP silicon small-signal transistor designed for audio-frequency input stages and driver circuits. It delivers high DC current gain (h_FE = 220–480 at I_C = 2 mA), low V_CE(sat) (max 300 mV at I_C = 10 mA / I_B = 0.5 mA), and low noise (1 dB typical at 1 kHz, 0.2 mA). It is AEC-Q101 qualified and RoHS-compliant in SOT23 package.

For engineers reviewing the BC857B datasheet, BC857B pinout, BC857B application, or BC857B equivalent, key selection criteria include its PNP polarity, 45 V V_CEO, 100 mA I_C, SOT23 footprint compatibility, and suitability for low-noise AF amplification and switching in automotive and industrial control modules.

Technical Context

The BC857B operates as a general-purpose PNP bipolar junction transistor with fixed-emitter biasing capability in linear and saturated switching modes. Its h_FE grouping (B) guarantees 220–480 gain at 2 mA collector current and 5 V V_CE, enabling stable biasing in discrete amplifier stages and level-shifting interfaces.

It features low base-emitter saturation voltage (V_BE(sat) ≤ 850 mV at I_C = 100 mA), low collector-base capacitance (C_cb = 1.5 pF typ), and f_T = 250 MHz - supporting reliable operation up to mid-VHF while maintaining low distortion in audio-band applications.

Key Specifications

Pinout & Package

BC857B is housed in a standard SOT23 plastic surface-mount package with gull-wing leads, optimized for automated placement and reflow soldering on 0.65 mm pitch PCBs.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar PNP small-signal transistor applications.

Compared with BC857BW and MMBT857, BC857B offers guaranteed AEC-Q101 compliance and SOT23 mechanical robustness for high-volume automotive assembly, while maintaining identical gain, voltage, and noise performance - making it the default choice for qualified production programs.

Availability

BC857B is available at Aetrix Electronics and suitable for automotive body electronics, industrial sensor interfaces, and audio signal conditioning requiring stable component supply and long-term lifecycle support.

Supply support for BC857B includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Nexperia is a global semiconductor expert focused on high-volume, high-reliability discrete and logic devices, with leadership in automotive-qualified components and energy-efficient solutions.

The BC856–BC860 series targets general-purpose PNP/NPN switching and amplification in space-constrained, thermally demanding environments - especially automotive infotainment, lighting, and power management subsystems.

FAQ

Is BC857B pin-compatible with BC847B?

No - BC857B is PNP while BC847B is NPN. They share identical SOT23 pinout (1=Base, 2=Emitter, 3=Collector), but polarity reversal means direct substitution will invert circuit behavior. Swapping requires redesigning bias networks and verifying current direction in all connected nodes.

What is the maximum operating temperature for BC857B in continuous operation?

The BC857B has a maximum junction temperature (T_j) of 150°C and a storage temperature range of –65°C to +150°C. At ambient temperatures above 71°C, power dissipation must be derated per the P_tot vs. T_S curve, with full 330 mW rated only when solder-point temperature stays ≤71°C.

Does BC857B support pulse operation beyond its DC ratings?

Yes - the datasheet specifies permissible pulse load curves showing P_tot(max)/P_tot(DC) ratios up to 10× for pulse widths ≤100 µs (duty cycle ≤5%). This enables short-duration peak currents up to 200 mA without exceeding thermal limits, provided average power remains within 330 mW.

Can BC857B replace BC857BL3 in the same PCB footprint?

No - BC857BL3 uses TSLP-3-1 package (0.65 mm pitch, 1.0 × 0.6 mm), while BC857B uses standard SOT23 (1.3 × 2.9 mm, 0.95 mm pitch). The footprints are mechanically incompatible; re-layout is required. Electrical specs are nearly identical, but thermal resistance differs (R_thJS = 60 K/W for BL3 vs. 240 K/W for B).