onsemi BC857BMTF

Overview

BC857BMTF from ON Semiconductor is a PNP epitaxial silicon transistor in SOT-23 package, rated for -45 V V_CEO, -100 mA I_C, and 310 mW power dissipation, with h_FE of 200–450 at -5 V V_CE and -2 mA I_C, used in low-noise amplifier and general-purpose switching circuits in portable power management and signal conditioning stages.

For engineers reviewing the BC857BMTF datasheet, pinout, applications, or equivalent options, key selection criteria include verified h_FE classification (B-grade), SOT-23 terminal mapping, V_CE(sat) ≤ −250 mV at −10 mA/−0.5 mA, noise figure of 2 dB (1 kHz), and compatibility with automated SMT assembly in space-constrained consumer and industrial PCBs.

Technical Context

This device operates as a discrete PNP bipolar junction transistor with epitaxial base construction, optimized for linear amplification and saturated switching. Its DC current gain (h_FE) is binned to 200–450, and its f_T reaches 150 MHz at −5 V V_CE and −10 mA I_C, supporting audio-frequency and low-speed digital signal handling.

Thermal performance is defined by a 150 °C maximum junction temperature and −65 to 150 °C storage range. The device exhibits low output capacitance (C_ob = 6 pF at −10 V V_CB) and specified saturation voltages: V_CE(sat) ≤ −250 mV and V_BE(sat) ≤ −700 mV under standard test conditions.

Key Specifications

Pinout & Package

SOT-23 surface-mount plastic package with 3-terminal configuration, footprint compatible with JEDEC TO-236AB standard, designed for high-density automated placement and reflow soldering.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BC857BMTF, BC857BW trades thermal robustness for miniaturization, while MMBT857 offers identical performance with updated branding and supply chain alignment-both require no schematic or layout changes when substituting in existing SOT-23 footprints.

Availability

BC857BMTF is available at Aetrix Electronics and suitable for portable audio preamps, LED driver switches, and level-shifting interfaces requiring stable component supply, consistent h_FE binning, and SOT-23 tape-and-reel logistics support.

Supply support for BC857BMTF 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

ON Semiconductor (formerly Fairchild Semiconductor) is a global supplier of energy-efficient semiconductor components, specializing in power management, analog, and discrete devices for automotive, industrial, and consumer markets.

The BC857BMTF belongs to the BC856–BC860 family of PNP epitaxial transistors, engineered for high-volume SMT applications demanding tight h_FE grading, low noise, and reliability in compact portable and battery-powered systems.

FAQ

What is the h_FE range for BC857BMTF?

The BC857BMTF is binned to a DC current gain (h_FE) range of 200 to 450 when measured at V_CE = −5 V and I_C = −2 mA. This B-grade specification ensures predictable biasing in amplifier and switching circuits without requiring external gain compensation. The h_FE value is laser-trimmed during manufacturing and marked as "9BB" on the SOT-23 package. BC857BMTF maintains this gain consistency across its operating temperature range.

What is the maximum collector-emitter voltage rating for BC857BMTF?

The BC857BMTF has a maximum collector-emitter voltage (V_CEO) rating of −45 V under DC conditions at T_A = 25 °C. This rating applies in common-emitter configuration with base open and defines the upper limit for safe operation before avalanche breakdown. Derating is required above 25 °C ambient, following the device's thermal resistance curve. BC857BMTF is not rated for repetitive or single-pulse overvoltage beyond this limit.

Does BC857BMTF support automated SMT assembly?

Yes, BC857BMTF is supplied in SOT-23 package with tape-and-reel packaging (3000 units per reel), fully compliant with IPC-7351 and JEDEC TO-236AB standards. Its 1.3 mm × 2.9 mm footprint, 0.95 mm lead pitch, and matte-finish molding compound ensure reliable pick-and-place accuracy and solder joint formation during reflow. BC857BMTF is qualified for Class 2 and Class 3 IPC-A-610 assembly processes.

What is the noise figure of BC857BMTF and at what conditions is it specified?

The BC857BMTF has a noise figure (NF) of 2 dB, measured at V_CE = −5 V, I_C = −200 µA, R_G = 2 kΩ, and f = 1 kHz. This low-noise performance is confirmed for the BC857 variant group (including BC857BMTF) and makes it suitable for front-end amplification in audio and sensor signal paths. NF degrades at higher frequencies and currents, so BC857BMTF should be biased within its specified low-noise operating region for optimal results.

How does BC857BMTF differ from BC857AMTF and BC857CMTF?

BC857BMTF differs from BC857AMTF and BC857CMTF solely in its h_FE bin: BC857AMTF is A-grade (110–220), BC857BMTF is B-grade (200–450), and BC857CMTF is C-grade (420–800). All share identical package (SOT-23), absolute ratings, pinout, and electrical characteristics except h_FE. The "B" suffix in BC857BMTF directly corresponds to the 200–450 gain range, and all variants use the same die process and marking format ("9BB" for BC857BMTF).