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Home > Products > Discrete Semiconductor Products > Transistors > Bipolar (BJT) > Single Bipolar Transistors

onsemi BC549TF

Name: BC549TF
Brand: onsemi
SKU: BC549TF
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: BC549TF

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

Package:: TO-226-3, TO-92-3 (TO-226AA) Formed Leads

Datasheet:: BC549TF.pdf

Description:: TRANS NPN 30V 0.1A TO-92-3

Quantity:: RFQ Add To RFQ list

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Product details

Overview

BC549TF from ON Semiconductor is an NPN epitaxial silicon transistor optimized for low-noise amplification and general-purpose switching in analog signal paths, with V_CEO = 30 V, h_FE = 420–800 (Class C), and f_T = 300 MHz - used in audio preamplifiers, sensor interface stages, and low-power linear regulators.

For engineers reviewing the BC549TF datasheet, pinout, applications, or equivalent options, key selection criteria include noise figure (1.4–4.0 dB at 30–15 kHz), TO-92 package thermal resistance, saturation voltage behavior at I_C = 10 mA / I_B = 0.5 mA, and h_FE classification consistency across production lots.

Technical Context

This device belongs to the BC546–BC550 family of through-hole NPN transistors fabricated using epitaxial base technology. It operates with V_EB0 = 5 V maximum, supports DC collector current up to 100 mA, and delivers low-noise performance specifically validated for V_CE = 5 V, I_C = 200 μA, R_G = 2 kΩ, and f = 30–15,000 Hz.

The BC549TF variant uses a TO-92 3-lead molded package with straight leads in tape-and-reel packaging (EIA-481-D compliant), and shares identical absolute maximum ratings and thermal limits (T_J = 150 °C, P_C = 500 mW) with other members of the family.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	30 V - Maximum safe collector-emitter voltage before breakdown; defines usable supply headroom in low-voltage amplifier stages.
h_FE (Class C)	420–800 - High DC current gain enables high-input-impedance common-emitter amplifiers with minimal base drive current.
f_T	300 MHz - Unity-gain bandwidth supports stable small-signal amplification up to mid-VHF range with proper biasing.
Noise Figure	1.4–4.0 dB - Measured at 30–15,000 Hz with V_CE = 5 V, I_C = 200 μA, R_G = 2 kΩ; critical for microphone preamps and instrumentation front-ends.
V_CE(sat)	90–250 mV @ I_C = 10 mA / I_B = 0.5 mA - Low saturation voltage reduces power loss and improves efficiency in switching applications.
P_C	500 mW - Maximum continuous power dissipation at T_A = 25 °C; derates linearly above 25 °C per 5.0 mW/°C junction-to-ambient thermal resistance.

Pinout & Package

BC549TF is housed in a JEDEC TO-92 3-lead plastic package with straight lead configuration (bulk/ammo/tape-and-reel variants). The package provides mechanical robustness, standard PCB mounting compatibility, and thermal performance suitable for low-power discrete designs.

Pin/Terminal	Circuit Role	Design Meaning
1 (Top View)	Collector	Main current output terminal; connects to load or next stage; requires heatsinking only under sustained >300 mW dissipation.
2 (Center)	Base	Control input; bias current here sets operating point; sensitive to ESD - requires series resistor in most layouts.
3 (Bottom)	Emiter	Current return path; typically grounded in common-emitter config; establishes reference for V_BE and h_FE stability.

Key Features

Feature	Design Value
Low-noise amplification	Validated NF = 1.4–4.0 dB in audio band (30–15 kHz), enabling high-fidelity signal conditioning without external noise filtering.
High h_FE Class C grading	Guaranteed h_FE ≥ 420 at I_C = 2 mA ensures predictable gain in bias-sensitive circuits like active filters and current mirrors.
TO-92 tape-and-reel packaging	EIA-481-D compliant reel format supports automated SMT-compatible through-hole placement and traceable lot-controlled assembly.
Complementary PNP pairing	Designed as direct complement to BC559 (same V_CEO, h_FE grading, and TO-92 footprint) for push-pull and differential pair implementations.

Applications

Audio Preamp Stage	Sensor Signal Conditioning
Use Scenario: Amplifying weak signals from electret microphones or piezoelectric sensors before ADC sampling. IC Role / Device Role / Timing Role: Discrete NPN transistor configured in common-emitter topology for voltage gain and impedance transformation. Use Value: Low 1.4–4.0 dB noise figure preserves SNR; h_FE ≥ 420 ensures stable bias with high-resistance voltage-divider networks.	Use Scenario: Converting low-level bridge outputs (e.g., load cells, RTDs) into amplified single-ended signals. IC Role / Device Role / Timing Role: Active element in discrete instrumentation amplifier front-end or emitter-follower buffer stage. Use Value: V_CEO = 30 V allows operation from ±15 V rails; f_T = 300 MHz supports wideband response up to 100 kHz without phase degradation.
Linear Voltage Regulator Pass Element	General-Purpose Switching Node
Use Scenario: Acting as series pass transistor in adjustable low-dropout regulators for embedded microcontroller supplies. IC Role / Device Role / Timing Role: Current-controlled linear regulator element with feedback via op-amp error amplifier. Use Value: V_CE(sat) ≤ 250 mV at I_C = 10 mA minimizes dropout voltage; P_C = 500 mW supports up to ~150 mA load at 3.3 V output.	Use Scenario: Driving LEDs, relays, or small solenoids from MCU GPIO pins in industrial control panels. IC Role / Device Role / Timing Role: Digital switch in common-emitter configuration with base current limiting and collector flyback protection. Use Value: Guaranteed h_FE ≥ 420 ensures full saturation with ≤1 mA base drive; TO-92 footprint simplifies manual prototyping and repair.

Audio Preamp Stage

Sensor Signal Conditioning

Use Scenario: Amplifying weak signals from electret microphones or piezoelectric sensors before ADC sampling.

IC Role / Device Role / Timing Role: Discrete NPN transistor configured in common-emitter topology for voltage gain and impedance transformation.

Use Value: Low 1.4–4.0 dB noise figure preserves SNR; h_FE ≥ 420 ensures stable bias with high-resistance voltage-divider networks.

Use Scenario: Converting low-level bridge outputs (e.g., load cells, RTDs) into amplified single-ended signals.

IC Role / Device Role / Timing Role: Active element in discrete instrumentation amplifier front-end or emitter-follower buffer stage.

Use Value: V_CEO = 30 V allows operation from ±15 V rails; f_T = 300 MHz supports wideband response up to 100 kHz without phase degradation.

Linear Voltage Regulator Pass Element

General-Purpose Switching Node

Use Scenario: Acting as series pass transistor in adjustable low-dropout regulators for embedded microcontroller supplies.

IC Role / Device Role / Timing Role: Current-controlled linear regulator element with feedback via op-amp error amplifier.

Use Value: V_CE(sat) ≤ 250 mV at I_C = 10 mA minimizes dropout voltage; P_C = 500 mW supports up to ~150 mA load at 3.3 V output.

Use Scenario: Driving LEDs, relays, or small solenoids from MCU GPIO pins in industrial control panels.

IC Role / Device Role / Timing Role: Digital switch in common-emitter configuration with base current limiting and collector flyback protection.

Use Value: Guaranteed h_FE ≥ 420 ensures full saturation with ≤1 mA base drive; TO-92 footprint simplifies manual prototyping and repair.

Equivalent & Alternatives

The following parts are listed as comparable options for similar NPN general-purpose transistor applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
BC549CTA	Same electrical specs and TO-92 package; differs only in packing method (ammo vs. tape-and-reel).	No functional difference; selected when manual or semi-automated insertion is preferred over pick-and-place.	Choose BC549CTA for low-volume prototyping or repair where reel handling is impractical.
2N3904	Lower h_FE (min 100 vs. 420), higher V_CEO (40 V vs. 30 V), and higher noise figure (5 dB typical); same TO-92 footprint.	Less suitable for low-noise audio or high-gain analog stages; better for digital switching with wider supply margin.	Choose 2N3904 when V_CEO > 30 V is required or when h_FE consistency is less critical than cost or availability.

Compared with BC549CTA, BC549TF offers identical performance but enables automated assembly via EIA-481-D tape-and-reel; versus 2N3904, BC549TF delivers superior noise performance and guaranteed high h_FE, making it preferable for precision analog signal chains despite tighter V_CEO margin.

Availability

BC549TF is available at Aetrix Electronics and suitable for audio preamplifier design, sensor interface circuitry, and low-power linear regulator implementation requiring stable component supply, consistent h_FE grading, and low-noise transistor performance.

Supply support for BC549TF 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 is a global semiconductor manufacturer specializing in energy-efficient power management, analog, and discrete devices for automotive, industrial, and consumer applications.

The BC549TF belongs to ON Semiconductor's legacy general-purpose transistor product line, originally developed by Fairchild and maintained for cost-sensitive, high-reliability linear and switching applications requiring proven TO-92 performance.

FAQ

What is the h_FE range for BC549TF, and how is it binned?

The BC549TF is classified as Class C, with a guaranteed DC current gain (h_FE) range of 420 to 800 when measured at V_CE = 5 V and I_C = 2 mA. This binning is performed during final test and marked on the device body as "C". Each BC549TF unit meets this specification, ensuring predictable gain behavior in amplifier and current-mirror designs without post-selection.

Does BC549TF have the same pinout as BC547 or BC550?

Yes, BC549TF uses the standard TO-92 pinout: Pin 1 = Collector, Pin 2 = Base, Pin 3 = Emitter - identical to BC546, BC547, BC548, BC550, and complementary BC556–BC560 series. This uniformity allows direct substitution in existing layouts where voltage and gain requirements align, though V_CEO and noise performance differ across the family.

What is the maximum operating temperature for BC549TF?

The BC549TF has a maximum junction temperature (T_J) of 150 °C and a storage temperature range of –65 °C to +150 °C. Its thermal resistance θ_JA is approximately 200 °C/W in free-air conditions, meaning power dissipation must be limited to ≤250 mW at ambient temperatures above 25 °C to maintain safe junction operation - a key constraint in enclosed or high-density PCB designs.

Is BC549TF suitable for RF applications?

The BC549TF has a current gain–bandwidth product (f_T) of 300 MHz, indicating capability for small-signal amplification up to VHF frequencies when properly biased and matched. However, it is not characterized for RF power gain, S-parameters, or stability beyond 30 MHz in official documentation; thus, BC549TF is best applied in low-noise IF/audio-frequency amplifiers rather than intentional RF transmitter or receiver front-ends.

How does BC549TF compare to BC549BTF in terms of specifications?

BC549TF and BC549BTF are identical in all electrical, thermal, and mechanical specifications - both are Class B (h_FE = 200–450), TO-92 packaged, tape-and-reel variants. The "F" suffix denotes tape-and-reel packaging per EIA-481-D; "TF" and "BTF" reflect historical Fairchild nomenclature where "T" = tape, "F" = reel, and "B" indicates Class B gain grade. BC549TF is the ON Semiconductor–updated designation replacing BC549BTF post-integration.

BC549TF Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

Package/Case:: TO-226-3, TO-92-3 (TO-226AA) Formed Leads

Packaging:: Tape & Reel (TR)

Product Status:: Obsolete

Transistor Type:: NPN

Current - Collector (Ic) (Max):: 100 mA

Voltage - Collector Emitter Breakdown (Max):: 30 V

Vce Saturation (Max) @ Ib, Ic:: 600mV @ 5mA, 100mA

Current - Collector Cutoff (Max):: 15nA (ICBO)

DC Current Gain (hFE) (Min) @ Ic, Vce:: 110 @ 2mA, 5V

Power - Max:: 500 mW

Frequency - Transition:: 300MHz

Operating Temperature:: 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-92-3

BC549TF FAQ

1.How can I place an order for BC549TF through Aetrix?

Please submit a Request for Quotation (RFQ) for BC549TF on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for BC549TF reliable?

The price and inventory of BC549TF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BC549TF is usually 5 days.

3.What payment methods are accepted for BC549TF?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BC549TF transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for BC549TF?

BC549TF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your BC549TF order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for BC549TF?

For technical support, including BC549TF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BC549TF requirements.

6.How does Aetrix verify that BC549TF is sourced from the original manufacturer or authorized distributors?

All BC549TF products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that BC549TF meets industry standards.

7.What is the process for return or replacement of BC549TF?

All BC549TF units undergo pre-shipment inspection (PSI). If there is an issue with BC549TF, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The BC549TF part is unused and in its original packaging.

Return procedure for BC549TF:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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