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

onsemi BC547CTAR

Name: BC547CTAR
Brand: onsemi
SKU: BC547CTAR
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: BC547CTAR

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

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

Datasheet:: BC547CTAR.pdf

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

Quantity:: RFQ Add To RFQ list

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Inventory:5,635

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Product details

Overview

BC547CTAR from ON Semiconductor is an NPN epitaxial silicon transistor designed for general-purpose switching and amplification in low-power analog and digital circuits. It features a DC current gain (h_FE) of 420–800 at I_C = 2 mA, V_CE = 5 V; V_CEO = 45 V; P_C = 500 mW; and TO-92 package with emitter-base voltage rating of 6 V. It is commonly used in signal amplification stages of audio preamps and discrete logic level shifting.

For engineers reviewing the BC547CTAR datasheet, pinout, applications, or equivalent options, key selection criteria include its h_FE classification (C-grade), saturation voltage performance at I_C = 10 mA / I_B = 0.5 mA (≤250 mV), noise figure (2.0–10.0 dB), f_T = 300 MHz, and compatibility with through-hole prototyping and legacy PCB designs.

Technical Context

The BC547CTAR operates as a standard bipolar junction transistor with fixed-emitter configuration and linear active-region behavior defined by its h_FE-I_C curve and V_BE(on) = 580–700 mV. Its junction temperature limit of 150°C and storage range of −65°C to +150°C support industrial ambient operation.

It exhibits low output capacitance (C_ob = 3.5–6.0 pF at V_CB = 10 V) and input capacitance (C_ib = 9 pF), enabling stable high-frequency small-signal amplification up to its f_T bandwidth limit. The device is not optimized for RF power but supports baseband audio and low-speed digital switching.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	45 V - Maximum safe collector-emitter voltage before breakdown; suitable for 24 V rail and automotive 12 V systems with margin.
h_FE (I_C = 2 mA)	420–800 - High DC gain enables low-base-drive current in amplifier bias networks and Darlington driver stages.
V_CE(sat) (I_C = 10 mA)	≤250 mV - Low saturation voltage minimizes power loss and heating in switching applications like LED drivers.
f_T	300 MHz - Supports amplification of signals up to ~100 MHz with usable gain; adequate for IF stages and pulse shaping.
P_C	500 mW - Continuous power dissipation at T_A = 25°C; requires heatsinking above ~200 mW in enclosed environments.
Package	TO-92 - Through-hole 3-pin plastic package with standardized lead spacing (0.2" line); compatible with manual soldering and wave soldering.

Pinout & Package

BC547CTAR uses the JEDEC-standard TO-92 package: molded plastic case with straight leads, 3-terminal configuration, and 0.2-inch lead spacing. Pin 1 is Collector, Pin 2 is Base, Pin 3 is Emitter - verified per Fairchild/ON Semiconductor mechanical drawings and ordering information tables.

Pin/Terminal	Circuit Role	Design Meaning
1 (Collector)	Output current sink node	Connected to load or next stage; must remain ≤45 V below emitter potential to avoid avalanche.
2 (Base)	Control input terminal	Receives forward-biased current to enable conduction; typical drive current 0.5–5 mA depending on load.
3 (Emitter)	Reference and current source node	Usually tied to ground or negative rail; defines V_BE threshold and sets emitter-follower output impedance.

Key Features

Feature	Design Value
High h_FE C-grade bin	Guaranteed 420–800 h_FE ensures consistent bias point stability across production lots in amplifier designs.
Low V_CE(sat)	≤250 mV at I_C = 10 mA enables efficient on-state operation in discrete switch configurations without external pull-down resistors.
Low-noise capability	Noise figure 2.0–10.0 dB at 1 kHz allows use in microphone preamplifiers and sensor signal conditioning where SNR matters.
JEDEC TO-92 compliance	Standardized mechanical footprint ensures interchangeability with BC546/BC548/BC549 variants and legacy board layouts.

Applications

Audio Pre-amplifier Stage	Discrete Logic Level Shifter
Use Scenario: Amplifying weak signals from electret microphones or piezoelectric sensors before ADC sampling. IC Role / Device Role / Timing Role: Small-signal NPN amplifier operating in common-emitter configuration with fixed bias network. Use Value: High h_FE and low noise figure (2.0–10.0 dB) preserve signal integrity while delivering >20 dB voltage gain at audio frequencies.	Use Scenario: Translating 3.3 V logic outputs to 5 V or 12 V loads in mixed-voltage embedded systems. IC Role / Device Role / Timing Role: Saturated switch driving relays, LEDs, or MOSFET gates with minimal propagation delay. Use Value: V_CE(sat) ≤250 mV and fast turn-on/turn-off (limited by f_T = 300 MHz) ensure clean edge transitions and low static power.
Linear Voltage Regulator Pass Element	Simple Oscillator Core (e.g., Royer)
Use Scenario: Acting as series pass transistor in adjustable linear regulators for low-noise analog rails. IC Role / Device Role / Timing Role: Linear-mode current source controlled by error amplifier feedback loop. Use Value: Stable h_FE and thermal robustness (T_J = 150°C) support continuous conduction with predictable dropout and thermal foldback.	Use Scenario: Building self-oscillating transformer-coupled inverters for CCFL backlight or low-power AC generation. IC Role / Device Role / Timing Role: Switching element in cross-coupled feedback topology with transformer secondary timing control. Use Value: Reliable saturation and recovery characteristics enable stable oscillation up to ~100 kHz without external timing capacitors.

Audio Pre-amplifier Stage

Discrete Logic Level Shifter

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

IC Role / Device Role / Timing Role: Small-signal NPN amplifier operating in common-emitter configuration with fixed bias network.

Use Value: High h_FE and low noise figure (2.0–10.0 dB) preserve signal integrity while delivering >20 dB voltage gain at audio frequencies.

Use Scenario: Translating 3.3 V logic outputs to 5 V or 12 V loads in mixed-voltage embedded systems.

IC Role / Device Role / Timing Role: Saturated switch driving relays, LEDs, or MOSFET gates with minimal propagation delay.

Use Value: V_CE(sat) ≤250 mV and fast turn-on/turn-off (limited by f_T = 300 MHz) ensure clean edge transitions and low static power.

Linear Voltage Regulator Pass Element

Simple Oscillator Core (e.g., Royer)

Use Scenario: Acting as series pass transistor in adjustable linear regulators for low-noise analog rails.

IC Role / Device Role / Timing Role: Linear-mode current source controlled by error amplifier feedback loop.

Use Value: Stable h_FE and thermal robustness (T_J = 150°C) support continuous conduction with predictable dropout and thermal foldback.

Use Scenario: Building self-oscillating transformer-coupled inverters for CCFL backlight or low-power AC generation.

IC Role / Device Role / Timing Role: Switching element in cross-coupled feedback topology with transformer secondary timing control.

Use Value: Reliable saturation and recovery characteristics enable stable oscillation up to ~100 kHz without external timing capacitors.

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
BC547BTA	Same TO-92 package; h_FE = 200–450 (B-grade), lower gain spread than BC547CTAR's 420–800 (C-grade).	Suitable for cost-sensitive switching where precise gain isn't critical; less ideal for low-noise amplification.	Select BC547BTA when gain consistency requirements are relaxed and BOM cost optimization is prioritized.
2N3904	V_CEO = 40 V (vs. 45 V), h_FE = 100–300, f_T = 300 MHz, same TO-92 package; slightly lower V_CEO and narrower h_FE range.	Widely available alternative with identical pinout; acceptable in most BC547CTAR switching roles but marginal in 45 V edge cases.	Choose 2N3904 only after verifying V_CEO margin suffices; not recommended for high-gain analog stages requiring C-grade h_FE.

Compared with BC547BTA and 2N3904, BC547CTAR delivers higher guaranteed h_FE, tighter gain distribution, and superior noise performance-making it preferred for precision amplification and low-distortion signal paths where C-grade binning adds design margin.

Availability

BC547CTAR is available at Aetrix Electronics and suitable for audio pre-amplification, discrete logic level translation, and linear regulator pass element applications requiring stable component supply and long-term obsolescence management.

Supply support for BC547CTAR 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 power management, analog, sensor, and discrete solutions for automotive, industrial, and consumer markets.

The BC547CTAR belongs to ON Semiconductor's legacy general-purpose bipolar transistor product line, originally developed by Fairchild and maintained for backward-compatible through-hole designs requiring proven reliability and wide temperature operation.

FAQ

What is the maximum collector-emitter voltage rating for BC547CTAR?

The BC547CTAR has a maximum collector-emitter voltage (V_CEO) rating of 45 V at T_A = 25°C. This rating applies under DC conditions with the base open; exceeding this value risks avalanche breakdown. Derating is required above 25°C ambient, per the absolute maximum ratings table in the official ON Semiconductor datasheet for BC547CTAR.

Is BC547CTAR suitable for low-noise audio amplification?

Yes, BC547CTAR is suitable for low-noise audio amplification. Its noise figure is specified as 2.0–10.0 dB at V_CE = 5 V, I_C = 200 μA, f = 1 kHz, and R_G = 2 kΩ - competitive with other general-purpose NPN transistors in its class. For best results, operate within its optimal I_C range (0.1–10 mA) and use proper shielding and grounding practices in the BC547CTAR circuit layout.

What does the "C" in BC547CTAR signify?

The "C" in BC547CTAR denotes the h_FE gain classification bin: BC547CTAR is guaranteed to have a DC current gain (h_FE) between 420 and 800 when measured at V_CE = 5 V and I_C = 2 mA. This distinguishes it from BC547ATA (A-grade: 110–220) and BC547BTA (B-grade: 200–450), enabling predictable biasing in high-gain amplifier designs.

Does BC547CTAR have a documented pinout configuration?

Yes, BC547CTAR has a documented JEDEC TO-92 pinout: Pin 1 is Collector, Pin 2 is Base, Pin 3 is Emitter - confirmed in the Fairchild/ON Semiconductor datasheet revision 1.1.1, Figure 7 and Figure 8. This orientation is viewed with the flat side facing the user and leads pointing downward; it matches industry-standard TO-92 layouts used across BC546–BC550 family members.

Can BC547CTAR replace BC547BTA in existing designs?

BC547CTAR can replace BC547BTA in most designs due to identical TO-92 package, pinout, and electrical ratings - but with higher minimum h_FE (420 vs. 200). This may shift bias points in amplifier circuits; verify quiescent current and gain stability. No PCB changes are needed, but revalidation of DC operating points and small-signal response is recommended when substituting BC547CTAR for BC547BTA.

BC547CTAR 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:: 420 @ 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

BC547CTAR FAQ

1.How can I place an order for BC547CTAR through Aetrix?

Please submit a Request for Quotation (RFQ) for BC547CTAR 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 BC547CTAR reliable?

The price and inventory of BC547CTAR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BC547CTAR is usually 5 days.

3.What payment methods are accepted for BC547CTAR?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BC547CTAR transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for BC547CTAR?

BC547CTAR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your BC547CTAR 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 BC547CTAR?

For technical support, including BC547CTAR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BC547CTAR requirements.

6.How does Aetrix verify that BC547CTAR is sourced from the original manufacturer or authorized distributors?

All BC547CTAR 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 BC547CTAR meets industry standards.

7.What is the process for return or replacement of BC547CTAR?

All BC547CTAR units undergo pre-shipment inspection (PSI). If there is an issue with BC547CTAR, 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 BC547CTAR part is unused and in its original packaging.

Return procedure for BC547CTAR:

1.Submit a request within 90 days.

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

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