onsemi BC859BMTF

Overview

BC859BMTF from Fairchild Semiconductor is a PNP epitaxial silicon transistor optimized for low-noise amplifier and general-purpose switching applications, with h_FE = 200–450, V_CEO = −30 V, I_C = −100 mA, and f_T = 150 MHz. It operates in SOT-23 package and is used in bias networks, signal inversion stages, and sensor interface front-ends.

For engineers reviewing the BC859BMTF datasheet, pinout, applications, or equivalent options, key selection criteria include verified DC current gain range, low-noise performance at 1 kHz, collector-emitter saturation voltage under defined drive conditions, and SOT-23 thermal derating behavior in high-density PCB layouts.

Technical Context

The BC859BMTF implements a planar PNP epitaxial structure with base-emitter junction optimized for stable h_FE across temperature and low 1/f noise. Its V_BE(sat) = −700 mV at I_C = −10 mA / I_B = −0.5 mA and Cob = 6 pF at V_CB = −10 V support fast switching in low-power logic interfaces and analog gain blocks.

It belongs to the BC856–BC860 family designed as complementary pairs to BC846–BC850 NPN devices. The BC859BMTF variant is specifically characterized for low-noise operation (NF = 1.2 dB at 30–15 kHz) and exhibits V_CE(sat) ≤ −300 mV at I_C = −100 mA / I_B = −5 mA, enabling efficient active-load configurations.

Key Specifications

Pinout & Package

SOT-23 plastic surface-mount package with gull-wing leads, 1.90 mm × 1.30 mm footprint, 1.14 mm max height, and JEDEC-compliant thermal pad layout.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BC859BMTF, BC857BMTF offers higher voltage headroom but trades 1.2 dB audio-band noise performance for it, while MMBT3906LT1G delivers superior f_T and lower capacitance at the cost of unverified low-noise behavior and looser h_FE binning.

Availability

BC859BMTF is available at Aetrix Electronics and suitable for audio preamplifiers, sensor interface circuits, and digital level-shifting applications requiring stable component supply, consistent h_FE binning, and low-noise analog performance.

Supply support for BC859BMTF 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

Fairchild Semiconductor was a U.S.-based semiconductor company specializing in power management, analog, and discrete components before its acquisition by ON Semiconductor in 2016.

The BC859BMTF belongs to the BC856–BC860 family of general-purpose PNP transistors engineered for low-noise amplification and reliable switching in space-constrained consumer and industrial electronics.

FAQ

What is the guaranteed h_FE range for BC859BMTF?

The BC859BMTF is binned to h_FE = 200–450 at V_CE = −5 V and I_C = −2 mA, confirmed per Fairchild's Rev. B datasheet ordering table. This B-grade specification applies to all BC859BMTF units marked "9DB" on the SOT-23 package, ensuring predictable bias point stability in production designs without individual device screening. The BC859BMTF h_FE range supports robust operation across temperature and supply variations in amplifier and switching circuits.

Does BC859BMTF support low-noise audio applications?

Yes, BC859BMTF is explicitly characterized for low-noise performance: NF = 1.2 dB measured at V_CE = −5 V, I_C = −200 µA, R_G = 2 kΩ, and f = 30–15,000 Hz. This specification is documented in the "Noise Figure" table of the BC856–BC860 datasheet and distinguishes BC859/BC860 variants from BC856–BC858. The BC859BMTF achieves this via optimized epitaxial base doping and junction geometry, making it suitable for electret microphone preamps and instrumentation front-ends.

What are the absolute maximum ratings for BC859BMTF?

The BC859BMTF has V_CBO = −30 V, V_CEO = −30 V, V_EBO = −5 V, I_C = −100 mA, P_C = 310 mW, T_J = 150°C, and T_STG = −65 to 150°C. These values are defined at T_A = 25°C unless otherwise noted and represent hard limits beyond which device reliability degrades. Derating curves apply above 25°C ambient, and pulse testing uses ≤300 µs width and ≤2% duty cycle. All BC859BMTF units comply with these absolute maximums per the official Fairchild datasheet.

Is BC859BMTF pin-compatible with other SOT-23 PNP transistors?

BC859BMTF uses standard SOT-23 pinout (1=Base, 2=Emitter, 3=Collector), matching industry convention for PNP devices in this package. However, pin compatibility alone does not guarantee functional interchangeability-BC859BMTF's h_FE binning, noise figure, and saturation characteristics differ from non-B-grade or non-BC859 variants. For example, substituting BC857BMTF requires verifying V_CEO margin and noise impact. Always validate circuit behavior with the exact BC859BMTF parameters before replacement.

What packaging format is supplied for BC859BMTF?

BC859BMTF is supplied in tape-and-reel format per the "MTF" suffix, with 3000 units per reel. The SOT-23 package conforms to JEDEC MO-178 standards, features gull-wing leads, and measures 1.90 mm × 1.30 mm × 1.14 mm max. This packaging enables direct integration into automated SMT lines without manual handling, and the matte finish ("M" suffix) reduces reflectivity during optical inspection. Each BC859BMTF reel is traceable and ESD-safe per ANSI/ESD S20.20.