onsemi BC849AMTF

Overview

BC849AMTF from Fairchild Semiconductor is an NPN epitaxial silicon transistor in SOT-23 package, rated for 30 V V_CEO, 100 mA I_C, and 310 mW P_C, with h_FE range 110–220, low noise (1.4 dB NF at 30–15 kHz), and f_T = 300 MHz - used in audio preamplifier stages and signal switching in portable instrumentation.

For engineers reviewing the BC849AMTF datasheet, pinout, applications, or equivalent options, key selection criteria include its low-noise performance in small-signal amplification, SOT-23 footprint compatibility with high-density PCB layouts, and h_FE classification A (110–220) for predictable DC bias stability in linear circuits.

Technical Context

The BC849AMTF operates as a general-purpose NPN bipolar junction transistor optimized for low-noise amplification and fast switching. Its V_CEO = 30 V and I_C = 100 mA support operation in battery-powered analog front-ends, while f_T = 300 MHz enables RF-coupled IF stages up to ~100 MHz.

It features V_BE(sat) = 700 mV at I_C = 10 mA/I_B = 0.5 mA and C_ob = 3.5–6 pF, enabling clean turn-off in digital logic interfaces and low-capacitance signal coupling in multi-stage amplifiers.

Key Specifications

Pinout & Package

SOT-23 surface-mount plastic package with gull-wing leads, 1.3 mm × 2.9 mm footprint, 1.1 mm height, and JEDEC MO-178 compliant outline.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BC849BMTF and MMBT3904LT1G, the BC849AMTF delivers tighter h_FE control and superior audio-band noise performance, making it preferred for precision low-level amplification where gain predictability and SNR are design-critical.

Availability

BC849AMTF is available at Aetrix Electronics and suitable for audio preamplifiers, sensor interface circuits, and RF intermediate frequency amplifiers requiring stable component supply and consistent h_FE binning.

Supply support for BC849AMTF 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 BC849AMTF belongs to the BC846–BC850 family of general-purpose NPN transistors designed for low-noise amplification and reliable switching in space-constrained consumer and industrial electronics.

FAQ

What is the h_FE range for BC849AMTF?

The BC849AMTF has a guaranteed DC current gain (h_FE) range of 110 to 220 at V_CE = 5 V and I_C = 2 mA, per its "A" classification marking. This binning ensures predictable bias point behavior in linear amplifier designs and simplifies resistor selection for stable quiescent current. The BC849AMTF's h_FE consistency supports production yield in high-volume analog modules where gain variation must stay within ±10%.

Does BC849AMTF support low-noise audio applications?

Yes, the BC849AMTF is explicitly characterized for low-noise operation with a noise figure of 1.4 dB at V_CE = 5 V, I_C = 200 μA, R_G = 2 kΩ, and frequency range 30–15,000 Hz. This makes the BC849AMTF suitable for microphone preamplifiers, ECG front-ends, and other sensitive analog signal paths where maintaining signal-to-noise ratio above 60 dB is essential. Its low-noise specification is validated per the original Fairchild BC846–BC850 Rev. B1 datasheet.

What is the maximum power dissipation of BC849AMTF?

The BC849AMTF has a maximum collector power dissipation (P_C) of 310 mW at T_A = 25°C in its SOT-23 package. Derating is required above 25°C at 2.48 mW/°C, meaning usable power drops to ~180 mW at 75°C ambient. This rating supports continuous operation in handheld devices and sensor nodes without forced cooling, provided board layout includes adequate copper pour for thermal conduction from the collector pad.

Is BC849AMTF pin-compatible with other transistors in the BC846–BC850 series?

Yes, all BC846–BC850 variants including BC849AMTF use identical SOT-23 packaging with standardized pinout: Pin 1 = Base, Pin 2 = Emitter, Pin 3 = Collector. This allows direct substitution among family members (e.g., BC847AMTF, BC848AMTF) on the same PCB footprint. However, electrical differences - especially V_CEO, V_CBO, and h_FE binning - must be verified for functional equivalence in the target circuit.

What is the typical transition frequency (f_T) of BC849AMTF?

The BC849AMTF has a typical current gain–bandwidth product (f_T) of 300 MHz at V_CE = 5 V, I_C = 10 mA, and f = 100 MHz. This value confirms its capability for small-signal amplification up to ~50 MHz with usable gain, and supports fast switching applications with rise/fall times under 100 ns. The f_T is measured under pulsed conditions (≤300 μs pulse width, ≤2% duty cycle) and remains stable across the specified h_FE range of the BC849AMTF.