onsemi BC858BMTF

Overview

BC858BMTF from Fairchild Semiconductor is a PNP epitaxial silicon transistor in SOT-23 package, rated for V_CEO = −30 V, I_C = −100 mA, and P_C = 310 mW, with h_FE = 200–450 at I_C = −2 mA, used in low-noise amplifier and general-purpose switching circuits.

For engineers reviewing the BC858BMTF datasheet, pinout, applications, or equivalent options, key selection criteria include its guaranteed h_FE bin (B), low V_CE(sat) (−250 mV @ I_C = −10 mA), noise figure (2 dB @ 1 kHz), SOT-23 footprint compatibility, and complementary pairing with BC847–BC850 NPN devices.

Technical Context

The BC858BMTF operates as a discrete PNP bipolar junction transistor with epitaxial base construction, optimized for linear amplification and saturated switching. Its DC current gain is binned to 200–450 (h_FE Class B), and it delivers low saturation voltage (−250 mV) under standard test conditions (I_C = −10 mA, I_B = −0.5 mA).

It features low output capacitance (C_ob = 6 pF @ V_CB = −10 V), moderate f_T = 150 MHz, and specified noise performance (NF = 2 dB @ V_CE = −5 V, I_C = −200 µA, R_G = 2 kΩ, f = 1 kHz), making it suitable for audio preamplifier stages and signal conditioning where low distortion and stable gain are required.

Key Specifications

Pinout & Package

SOT-23 plastic surface-mount package with gull-wing leads, 1.90 mm × 1.30 mm body size, 0.95 mm lead pitch, and JEDEC MO-215 compliant dimensions.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BC858BMTF, BC858BW offers identical performance with added wafer traceability, while MMBT858 provides cross-manufacturer supply resilience without layout or bias redesign-both require no PCB changes and maintain full functional equivalence in linear and switching modes.

Availability

BC858BMTF is available at Aetrix Electronics and suitable for audio preamplifiers, logic-level translators, and current mirror reference circuits requiring stable component supply and consistent h_FE binning.

Supply support for BC858BMTF 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 designer and manufacturer of analog and discrete semiconductors, acquired by ON Semiconductor in 2016; known for robust, industry-standard small-signal transistors.

The BC858BMTF belongs to the BC856–BC860 family of PNP epitaxial silicon transistors engineered for general-purpose amplification and switching in space-constrained, cost-sensitive consumer and industrial electronics.

FAQ

What is the h_FE range guaranteed for BC858BMTF?

The BC858BMTF is binned to h_FE Class B, guaranteeing a DC current gain of 200–450 when measured at V_CE = −5 V and I_C = −2 mA. This binning ensures predictable biasing behavior in amplifier and switching circuits without requiring gain-dependent design margins. The BC858BMTF specification sheet explicitly defines this range in its h_FE Classification table.

Is BC858BMTF pin-compatible with BC847 or BC848 NPN transistors?

No, BC858BMTF is not pin-compatible with BC847 or BC848 because it is a PNP device while those are NPN-pin 1 is Base for both, but polarity and internal junction orientation differ. However, BC858BMTF shares the same SOT-23 footprint and pinout assignment (1=Base, 2=Emitter, 3=Collector), enabling mechanical compatibility in layouts designed for complementary pairs. The BC858BMTF datasheet confirms pin definitions on page 2.

What is the maximum power dissipation of BC858BMTF at room temperature?

The BC858BMTF has a maximum collector power dissipation (P_C) of 310 mW at T_A = 25°C, as stated in the Absolute Maximum Ratings table. Derating is required above 25°C at 2.48 mW/°C, per the thermal resistance specification. This value applies to the SOT-23 package in free-air conditions and is confirmed in the August 2006 Rev. B datasheet.

Does BC858BMTF support low-noise audio applications?

Yes, BC858BMTF is specified for low-noise operation with a noise figure of 2 dB at V_CE = −5 V, I_C = −200 µA, R_G = 2 kΩ, and f = 1 kHz-explicitly noted in the Electrical Characteristics table. This makes the BC858BMTF suitable for microphone preamplifiers and sensor interface stages where signal integrity is critical.

What does the "TF" suffix in BC858BMTF indicate?

Per the Ordering Information table in the BC856–BC860 datasheet, the "TF" suffix denotes tape-and-reel packaging, with 3000 units per reel. It does not affect electrical performance or reliability. The BC858BMTF marking "9CB" on the device body corresponds to this h_FE Class B, SOT-23, tape-and-reel variant.