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

onsemi BC550BTA

Name: BC550BTA
Brand: onsemi
SKU: BC550BTA
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: BC550BTA

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

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

Datasheet:: BC550BTA.pdf

Description:: TRANS NPN 45V 0.1A TO-92-3

Quantity:: RFQ Add To RFQ list

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Product details

Overview

BC550BTA from ON Semiconductor is a low-noise NPN epitaxial silicon transistor in TO-92 package, rated for V_CEO = 45 V, I_C = 100 mA, and h_FE = 200–450 (Class B), with f_T = 300 MHz and NF = 1.4–3.0 dB at 1 kHz. It serves as a general-purpose amplifier or switching device in audio preamplifier stages and signal conditioning circuits.

For engineers reviewing the BC550BTA datasheet, pinout, applications, or equivalent options, key selection criteria include its low-noise performance, TO-92 mechanical compatibility, DC current gain classification, saturation voltage behavior under 10 mA/0.5 mA drive, and junction temperature limit of 150°C.

Technical Context

This transistor operates as a discrete bipolar junction device with epitaxial base construction optimized for low-noise amplification. Its h_FE range (200–450) and specified noise figure (1.4–3.0 dB) are validated at V_CE = 5 V, I_C = 200 μA, R_G = 2 kΩ, and f = 1 kHz - conditions aligned with small-signal audio front-end design.

The BC550BTA shares absolute maximum ratings with the BC549/BC550 family: V_CBO = 50 V, V_EBO = 5 V, P_C = 500 mW, and T_J = 150°C. Its f_T of 300 MHz supports stable operation up to mid-VHF frequencies when biased appropriately.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	45 V - Maximum collector-emitter voltage before breakdown; defines safe operating range in common-emitter amplifier configurations.
h_FE (Class B)	200–450 - DC current gain range at V_CE = 5 V, I_C = 2 mA; determines base drive requirements for linear or saturated operation.
f_T	300 MHz - Current gain bandwidth product; indicates usable frequency limit for small-signal amplification with unity-gain stability margin.
Noise Figure	1.4–3.0 dB - Measured at V_CE = 5 V, I_C = 200 μA, R_G = 2 kΩ, f = 1 kHz; enables high-fidelity audio preamp stage design with minimal added noise.
V_CE(sat)	90–250 mV - Collector-emitter saturation voltage at I_C = 10 mA, I_B = 0.5 mA; defines conduction loss and thermal rise in switching applications.
P_C	500 mW - Maximum power dissipation at T_A = 25°C; sets thermal derating curve for PCB layout and heatsinking decisions.

Pinout & Package

BC550BTA is housed in a JEDEC TO-92 3-lead molded plastic package with straight leads (ammo pack format). Pin identification follows standard TO-92 orientation: flat side facing user, leads down, left-to-right = Emitter (1), Base (2), Collector (3).

Pin/Terminal	Circuit Role	Design Meaning
1 (Left)	Emitter	Current output terminal; connects to ground or bias network in common-emitter configuration; polarity defines NPN operation.
2 (Center)	Base	Control input; requires current-limited drive (e.g., via resistor) to achieve target h_FE-dependent collector current.
3 (Right)	Collector	Current input terminal; connects to load or supply rail; voltage swing limited by V_CEO = 45 V rating.

Key Features

Feature	Design Value
Low-noise amplification	1.4–3.0 dB noise figure at audio frequencies enables use in microphone preamps and sensor signal conditioning without significant SNR degradation.
High DC current gain	h_FE = 200–450 (Class B) reduces required base drive current, easing interface with microcontroller GPIO or op-amp outputs.
TO-92 mechanical standardization	JEDEC-compliant 3-lead through-hole package ensures compatibility with legacy PCB footprints and manual assembly workflows.
300 MHz f_T	Supports stable small-signal amplification up to ~100 MHz with proper biasing and layout, suitable for RF detector and IF amplifier stages.

Applications

Audio Preamp Stage	Signal Conditioning Circuit
Use Scenario: Amplifying weak signals from electret microphones or piezoelectric sensors before ADC sampling. IC Role / Device Role / Timing Role: Low-noise NPN transistor configured in common-emitter topology for voltage gain. Use Value: 1.4–3.0 dB noise figure preserves signal integrity at sub-mV levels, minimizing audible hiss in consumer audio systems.	Use Scenario: Buffering and level-shifting analog sensor outputs (e.g., thermistor, photodiode) into microcontroller input ranges. IC Role / Device Role / Timing Role: Linear amplifier with adjustable gain via emitter degeneration resistor. Use Value: h_FE = 200–450 allows predictable gain setting and stable DC bias point across temperature.
Switching Load Driver	RF Detector Stage
Use Scenario: Driving LEDs, relays, or small solenoids from logic-level control signals. IC Role / Device Role / Timing Role: Saturated switch with low V_CE(sat) (90–250 mV) to minimize power loss. Use Value: 500 mW power rating and 150°C junction temperature support intermittent duty-cycle loads without thermal shutdown.	Use Scenario: Demodulating AM signals or detecting RF envelope in low-cost receivers. IC Role / Device Role / Timing Role: Nonlinear junction used as diode-connected detector with f_T = 300 MHz bandwidth. Use Value: High f_T enables detection up to ~50 MHz while maintaining adequate sensitivity and linearity.

Audio Preamp Stage

Signal Conditioning Circuit

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

IC Role / Device Role / Timing Role: Low-noise NPN transistor configured in common-emitter topology for voltage gain.

Use Value: 1.4–3.0 dB noise figure preserves signal integrity at sub-mV levels, minimizing audible hiss in consumer audio systems.

Use Scenario: Buffering and level-shifting analog sensor outputs (e.g., thermistor, photodiode) into microcontroller input ranges.

IC Role / Device Role / Timing Role: Linear amplifier with adjustable gain via emitter degeneration resistor.

Use Value: h_FE = 200–450 allows predictable gain setting and stable DC bias point across temperature.

Switching Load Driver

RF Detector Stage

Use Scenario: Driving LEDs, relays, or small solenoids from logic-level control signals.

IC Role / Device Role / Timing Role: Saturated switch with low V_CE(sat) (90–250 mV) to minimize power loss.

Use Value: 500 mW power rating and 150°C junction temperature support intermittent duty-cycle loads without thermal shutdown.

Use Scenario: Demodulating AM signals or detecting RF envelope in low-cost receivers.

IC Role / Device Role / Timing Role: Nonlinear junction used as diode-connected detector with f_T = 300 MHz bandwidth.

Use Value: High f_T enables detection up to ~50 MHz while maintaining adequate sensitivity and linearity.

Equivalent & Alternatives

The following parts are listed as comparable options for similar NPN low-noise transistor applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
BC549BTA	Identical V_CEO, V_EBO, P_C, and h_FE class; same noise figure (1.4–4.0 dB), but rated for lower V_CBO (30 V vs. 50 V).	Less suitable in higher-voltage collector bias networks where V_CB may exceed 30 V.	Select BC549BTA only if V_CB remains below 30 V and identical noise performance is acceptable.
2N3904	Higher V_CEO (40 V), lower h_FE (100–300), higher noise figure (5 dB typ.), and no Class B gain binning.	Not recommended for low-noise audio; better suited for general-purpose switching where gain consistency is less critical.	Choose 2N3904 only when cost or availability outweighs noise and gain-bin requirements.

Compared with BC549BTA and 2N3904, BC550BTA offers superior noise performance and tighter h_FE binning for precision analog designs, while maintaining full TO-92 footprint compatibility and 45 V collector-emitter blocking capability.

Availability

BC550BTA is available at Aetrix Electronics and suitable for audio preamplifiers, sensor signal conditioning circuits, and low-power switching loads requiring stable component supply and consistent low-noise transistor performance.

Supply support for BC550BTA 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 and signal management solutions, with roots in Fairchild Semiconductor's discrete transistor legacy.

The BC550BTA belongs to ON Semiconductor's legacy general-purpose bipolar transistor product line, designed for cost-sensitive, high-reliability analog and switching applications in consumer, industrial, and communications equipment.

FAQ

What is the maximum collector-emitter voltage rating for BC550BTA?

The BC550BTA has a maximum collector-emitter voltage (V_CEO) rating of 45 V at T_A = 25°C. This value defines the upper limit for safe DC operation in common-emitter configurations. Exceeding this voltage risks avalanche breakdown and permanent device damage. Derating is required above 25°C ambient per the datasheet thermal curves.

Does BC550BTA have a specified noise figure, and under what conditions is it measured?

Yes, BC550BTA has a noise figure of 1.4–3.0 dB, measured at V_CE = 5 V, I_C = 200 μA, source resistance R_G = 2 kΩ, and frequency f = 1 kHz. This specification confirms its suitability for low-noise small-signal amplification, particularly in audio front-end stages where signal integrity is critical.

What is the h_FE range for BC550BTA, and how is it binned?

The BC550BTA is classified as Class B, with a guaranteed DC current gain (h_FE) range of 200 to 450 at V_CE = 5 V and I_C = 2 mA. This binning is performed during final test and marked on the device body as "BC550B". It ensures predictable base drive requirements across production lots.

Is BC550BTA compatible with standard TO-92 footprints, and what is its pin configuration?

Yes, BC550BTA uses a JEDEC-standard TO-92 3-lead package with straight leads. When viewed with the flat side facing the user and leads pointing downward, the pin order left-to-right is Emitter (1), Base (2), Collector (3). This matches industry-standard TO-92 layouts and supports drop-in replacement in existing designs.

What is the power dissipation limit of BC550BTA, and how does junction temperature affect it?

BC550BTA has a maximum collector power dissipation (P_C) of 500 mW at T_A = 25°C. Its maximum junction temperature is 150°C. Above 25°C ambient, P_C must be linearly derated - typically by 4.5 mW/°C - to prevent thermal runaway. Proper PCB copper area and airflow are essential for sustained operation near rated limits.

BC550BTA Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

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

Packaging:: Tape & Box (TB)

Product Status:: Obsolete

Transistor Type:: NPN

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

Voltage - Collector Emitter Breakdown (Max):: 45 V

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

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

DC Current Gain (hFE) (Min) @ Ic, Vce:: 200 @ 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

BC550BTA FAQ

1.How can I place an order for BC550BTA through Aetrix?

Please submit a Request for Quotation (RFQ) for BC550BTA 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 BC550BTA reliable?

The price and inventory of BC550BTA are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BC550BTA is usually 5 days.

3.What payment methods are accepted for BC550BTA?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BC550BTA transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for BC550BTA?

BC550BTA orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your BC550BTA 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 BC550BTA?

For technical support, including BC550BTA datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BC550BTA requirements.

6.How does Aetrix verify that BC550BTA is sourced from the original manufacturer or authorized distributors?

All BC550BTA 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 BC550BTA meets industry standards.

7.What is the process for return or replacement of BC550BTA?

All BC550BTA units undergo pre-shipment inspection (PSI). If there is an issue with BC550BTA, 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 BC550BTA part is unused and in its original packaging.

Return procedure for BC550BTA:

1.Submit a request within 90 days.

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

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