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onsemi BC549BTF
- Part No.:
- BC549BTF
- Manufacturer:
- onsemi
- Category:
- Single Bipolar Transistors
- Package:
- TO-226-3, TO-92-3 (TO-226AA) Formed Leads
- Datasheet:
-
BC549BTF.pdf
- Description:
- TRANS NPN 30V 0.1A TO-92-3
- Quantity:
- Payment:
- Shipping:
Inventory:12,226
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Product details
Overview
BC549BTF from ON Semiconductor is a low-noise NPN epitaxial silicon transistor in TO-92 package, rated for VCEO = 30 V, IC = 100 mA, and hFE = 200–450 (Class B), optimized for audio preamplifier and signal amplification stages where noise figure ≤ 4.0 dB at 200 µA/5 V is critical.
For engineers reviewing the BC549BTF datasheet, pinout, applications, or equivalent options, this page delivers verified pin configuration, low-noise design context, TO-92 terminal mapping, and two validated alternative transistors with documented hFE and noise performance differences.
Technical Context
This device operates as a general-purpose bipolar junction transistor with fixed NPN polarity, fabricated using epitaxial silicon process to achieve low base spreading resistance and controlled minority-carrier lifetime. Its low-noise specification (NF = 1.4–4.0 dB) is validated at VCE = 5 V, IC = 200 µA, RG = 2 kΩ, f = 30–15,000 MHz - distinct from BC546/BC547 variants.
It shares absolute maximum ratings with BC548/BC549 family members: VCEO = 30 V, VEBO = 5 V, PC = 500 mW, TJ = 150 °C. The hFE classification (B: 200–450) and fT = 300 MHz at IC = 10 mA confirm suitability for mid-frequency analog gain stages, not RF power switching.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCEO | 30 V - Maximum collector-emitter voltage before breakdown; defines safe linear operation ceiling in amplifier bias networks. |
| hFE (Class B) | 200–450 - DC current gain range at VCE = 5 V, IC = 2 mA; enables predictable bias point stability in common-emitter amplifiers. |
| Noise Figure | 1.4–4.0 dB - Measured at VCE = 5 V, IC = 200 µA, RG = 2 kΩ, 30–15,000 MHz; qualifies BC549BTF for low-noise audio front-end use. |
| fT | 300 MHz - Current gain–bandwidth product at VCE = 5 V, IC = 10 mA; supports stable gain up to ~10–50 MHz depending on circuit Q. |
| VCE(sat) | 90–250 mV @ IC = 10 mA, IB = 0.5 mA - Low saturation voltage ensures minimal voltage drop in active-load or switching applications. |
| Cob | 3.5–6.0 pF @ VCB = 10 V - Output capacitance limits high-frequency gain roll-off and affects Miller effect in common-emitter configurations. |
Pinout & Package
BC549BTF uses JEDEC-standard TO-92 3-lead plastic package with straight lead configuration (bulk/ammo/tape-and-reel variants). Lead identification is fixed: Pin 1 = Collector, Pin 2 = Base, Pin 3 = Emitter - confirmed per Fairchild BC546–BC550 Rev. 1.1.1 physical dimensions and marking diagrams.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (Collector) | Main current output terminal | Connected to load or next stage input; must remain within 30 V VCEO limit and 100 mA IC rating under all operating conditions. |
| 2 (Base) | Control input for minority-carrier injection | Requires current-limited drive (e.g., via 10–100 kΩ resistor); base-emitter forward voltage is 580–700 mV at IC = 2 mA. |
| 3 (Emitter) | Current return path and reference node | Typically tied to ground or emitter degeneration resistor; VEBO = 5 V max defines reverse-bias safety margin. |
Key Features
| Feature | Design Value |
|---|---|
| Low-noise amplification | 1.4–4.0 dB NF at audio/mid-band frequencies enables use in microphone preamps and sensor signal conditioning without added noise floor. |
| Controlled hFE spread (Class B) | 200–450 gain range allows predictable DC biasing in discrete amplifier designs without individual transistor matching. |
| High fT (300 MHz) | Supports stable small-signal gain beyond audio band into VHF region, suitable for IF amplifiers and oscillator buffer stages. |
| TO-92 compatibility | Standardized footprint and thermal resistance (RθJA ≈ 200 °C/W) enable drop-in replacement in legacy through-hole PCB layouts. |
Applications
| Audio Preamp Stage | Signal Conditioning Amplifier |
|---|---|
|
Use Scenario: Amplifying weak signals from electret microphones or piezoelectric sensors in battery-powered voice recorders. IC Role / Device Role / Timing Role: NPN small-signal amplifier in common-emitter configuration with emitter degeneration. Use Value: 1.4–4.0 dB noise figure preserves signal-to-noise ratio; hFE = 200–450 ensures stable 20–40 dB voltage gain with minimal distortion. |
Use Scenario: Boosting analog outputs from temperature or light sensors before ADC sampling in industrial monitoring nodes. IC Role / Device Role / Timing Role: Linear gain block with DC-coupled input and output, biased for low quiescent current. Use Value: VCEO = 30 V and PC = 500 mW allow operation from 12 V rails with thermal margin; Cob = 3.5–6.0 pF minimizes bandwidth loss. |
| Low-Power Oscillator Buffer | Discrete Logic Level Shifter |
|
Use Scenario: Isolating and driving crystal oscillator outputs to multiple downstream clock inputs in embedded MCU systems. IC Role / Device Role / Timing Role: Emitter-follower buffer providing low-output-impedance drive without loading the oscillator core. Use Value: fT = 300 MHz ensures flat response up to 10 MHz; VCE(sat) ≤ 250 mV maintains logic-high level integrity across temperature. |
Use Scenario: Translating 3.3 V logic signals to 5 V or 12 V levels for legacy peripherals in mixed-voltage control panels. IC Role / Device Role / Timing Role: Saturated switch in common-emitter configuration with base current limiting. Use Value: IC = 100 mA rating supports ≥20 mA output drive; VEBO = 5 V permits safe reverse-base operation during level transitions. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar NPN small-signal transistor applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| BC549CTF | hFE = 420–800 (Class C), identical VCEO = 30 V, NF = 1.4–4.0 dB | Higher gain enables lower base drive current but reduces bias stability margin in temperature-sensitive circuits | Select BC549CTF when higher open-loop gain is required and thermal drift compensation is implemented |
| 2N3904TA | VCEO = 40 V, hFE = 100–300, NF = 5.0 dB (typical), fT = 300 MHz | Higher voltage rating but higher noise and narrower hFE range; not specified for low-noise audio use | Choose 2N3904TA only when VCEO > 30 V is mandatory and noise < 4 dB is not required |
Compared with BC549BTF, BC549CTF offers higher gain at same noise performance but reduced bias predictability, while 2N3904TA trades noise and hFE consistency for greater voltage headroom - making BC549BTF optimal for precision low-noise amplification where gain stability matters.
Availability
BC549BTF is available at Aetrix Electronics and suitable for audio preamplifier circuits, sensor signal conditioning modules, and low-power oscillator buffer designs requiring stable component supply and full traceability.
Supply support for BC549BTF 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 (formerly Fairchild Semiconductor) is a global semiconductor manufacturer specializing in power management, analog, and discrete devices for automotive, industrial, and consumer markets.
The BC549BTF belongs to the BC546–BC550 family of general-purpose NPN transistors designed specifically for low-noise audio amplification and reliable linear signal processing in cost-sensitive through-hole applications.
FAQ
What is the pin configuration of BC549BTF?
The BC549BTF uses standard TO-92 pinout: Pin 1 is Collector, Pin 2 is Base, and Pin 3 is Emitter - confirmed in Fairchild's BC546–BC550 Rev. 1.1.1 datasheet Figure 7 and 8. This configuration is consistent across all BC546–BC550 variants and matches JEDEC TO-92 mechanical specifications. No alternate pinouts exist for BC549BTF.
What does the 'B' in BC549BTF signify?
The 'B' in BC549BTF denotes hFE classification: BC549B has a DC current gain range of 200–450 at VCE = 5 V and IC = 2 mA. This distinguishes it from BC549A (110–220) and BC549C (420–800). The 'TF' suffix indicates tape-and-reel packaging per Fairchild ordering nomenclature.
Is BC549BTF suitable for low-noise audio applications?
Yes, BC549BTF is explicitly characterized for low-noise operation: its noise figure is 1.4–4.0 dB at VCE = 5 V, IC = 200 µA, RG = 2 kΩ, and f = 30–15,000 MHz - a specification highlighted in the "Features" section of the BC546–BC550 datasheet. This makes BC549BTF appropriate for microphone preamplifiers and sensor front-ends.
How does BC549BTF differ from BC547BTF?
BC549BTF and BC547BTF share TO-92 packaging and Class B hFE (200–450), but differ critically in voltage ratings and noise: BC549BTF has VCEO = 30 V and NF = 1.4–4.0 dB, while BC547BTF has VCEO = 45 V and NF = 2.0–10.0 dB. Thus, BC549BTF is optimized for low-noise, BC547BTF for higher-voltage general-purpose use.
What is the maximum power dissipation of BC549BTF?
The BC549BTF has a maximum collector power dissipation (PC) of 500 mW at TA = 25 °C, as specified in the Absolute Maximum Ratings table. Derating is required above 25 °C - approximately 4.5 mW/°C - to maintain junction temperature below 150 °C. This value applies identically across all BC546–BC550 variants in TO-92 packages.
BC549BTF 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:
- 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
BC549BTF FAQ
1.How can I place an order for BC549BTF through Aetrix?
Please submit a Request for Quotation (RFQ) for BC549BTF 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 BC549BTF reliable?
The price and inventory of BC549BTF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BC549BTF is usually 5 days.
3.What payment methods are accepted for BC549BTF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BC549BTF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for BC549BTF?
BC549BTF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your BC549BTF 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 BC549BTF?
For technical support, including BC549BTF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BC549BTF requirements.
6.How does Aetrix verify that BC549BTF is sourced from the original manufacturer or authorized distributors?
All BC549BTF 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 BC549BTF meets industry standards.
7.What is the process for return or replacement of BC549BTF?
All BC549BTF units undergo pre-shipment inspection (PSI). If there is an issue with BC549BTF, 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 BC549BTF part is unused and in its original packaging.
Return procedure for BC549BTF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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