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onsemi BC549BTFR
- Part No.:
- BC549BTFR
- Manufacturer:
- onsemi
- Category:
- Single Bipolar Transistors
- Package:
- TO-226-3, TO-92-3 (TO-226AA) Formed Leads
- Datasheet:
-
BC549BTFR.pdf
- Description:
- TRANS NPN 30V 0.1A TO-92-3
- Quantity:
- Payment:
- Shipping:
Inventory:6,798
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Product details
Overview
BC549BTFR from ON Semiconductor is an NPN epitaxial silicon transistor optimized for low-noise amplification and general-purpose switching in analog signal paths, with VCEO = 30 V, IC = 100 mA, hFE = 420–800 (Class C), and NF = 1.4–4.0 dB at 30–15 kHz. It operates in TO-92 package and is commonly used in audio preamplifiers, sensor interface stages, and low-power linear regulators.
For engineers reviewing the BC549BTFR datasheet, pinout, applications, or equivalent options, key selection criteria include noise figure at 200 µA bias, hFE classification consistency across temperature, saturation voltage under 10 mA/0.5 mA drive, and TO-92 mechanical compatibility with legacy BC-series layouts.
Technical Context
This device belongs to the BC546–BC550 family of through-hole NPN transistors, sharing identical TO-92 packaging, pinout (C-B-E), and absolute maximum ratings across variants. Its low-noise design targets small-signal amplification where VCE = 5 V, IC = 200 µA, and RG = 2 kΩ define the reference test condition.
Unlike BC546/BC547, BC549 specifies tighter noise performance (1.4–4.0 dB) and lower VCEO (30 V), while maintaining compatible DC gain behavior and thermal limits (TJ = 150 °C, PC = 500 mW). It is electrically complementary to BC559 PNP transistors in push-pull configurations.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCEO | 30 V - Maximum safe collector-emitter voltage before breakdown; defines usable supply headroom in amplifier stages. |
| hFE (Class C) | 420–800 - Confirmed DC current gain range at VCE = 5 V, IC = 2 mA; ensures predictable bias stability in emitter-follower or common-emitter designs. |
| NF | 1.4–4.0 dB - Measured noise figure at f = 30–15,000 MHz, VCE = 5 V, IC = 200 µA, RG = 2 kΩ; critical for high-fidelity audio and precision sensor front-ends. |
| VCE(sat) | 250–600 mV - Collector-emitter saturation voltage at IC = 100 mA, IB = 5 mA; determines conduction loss in switching applications. |
| fT | 300 MHz - Current gain–bandwidth product at VCE = 5 V, IC = 10 mA; supports RF amplification up to ~100 MHz with adequate gain margin. |
| VEBO | 5 V - Maximum reverse emitter-base voltage; constrains base drive circuit design in active-clamp or level-shifted configurations. |
Pinout & Package
BC549BTFR is housed in a JEDEC TO-92 3-lead molded plastic package with straight leads (tape-and-reel packing format). Dimensions conform to standard TO-92 mechanical outline (0.2" lead spacing).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (Top View, Flat Side Up) | Collector | Main current output terminal; connects to load or next stage; requires heatsinking only above ~500 mW dissipation. |
| 2 | Base | Control input; bias current here sets operating point; sensitive to ESD due to thin oxide layer. |
| 3 | Emitter | Current return path; often tied to ground or negative rail; establishes reference for VBE and hFE calculations. |
Key Features
| Feature | Design Value |
|---|---|
| Low-noise amplification | 1.4–4.0 dB NF at audio and mid-band frequencies enables use in microphone preamps without added op-amp noise penalty. |
| High hFE Class C grading | 420–800 hFE range ensures consistent DC biasing across production lots, reducing need for manual gain binning in volume production. |
| TO-92 mechanical compatibility | Standard 0.2" lead pitch and footprint allows drop-in replacement for BC546–BC550 series in existing PCBs and sockets. |
| Complementary PNP pairing | Designed as direct match to BC559; enables matched differential pairs and Class AB output stages with symmetrical distortion profiles. |
Applications
| Audio Preamp Stage | Sensor Signal Conditioning |
|---|---|
|
Use Scenario: Amplifying weak signals from electret microphones or piezoelectric sensors in battery-powered voice recorders. IC Role / Device Role / Timing Role: Small-signal NPN amplifier in common-emitter configuration with emitter degeneration. Use Value: 1.4 dB minimum noise figure preserves SNR at sub-mV input levels without requiring ultra-low-noise op-amps. |
Use Scenario: Buffering and gain-setting for thermistor or photodiode outputs in industrial monitoring modules. IC Role / Device Role / Timing Role: Transimpedance or voltage follower stage providing isolation and stable DC bias. Use Value: 420–800 hFE ensures predictable gain accuracy across temperature (−55°C to +150°C junction range). |
| Linear Voltage Regulator Pass Element | Discrete Logic-Level Switch |
|
Use Scenario: Low-dropout pass transistor in 5 V fixed-output regulators for embedded MCU power rails. IC Role / Device Role / Timing Role: Series pass element controlled by error amplifier feedback loop. Use Value: 250 mV typical VCE(sat) at 10 mA reduces dropout voltage and improves efficiency at light loads. |
Use Scenario: Driving LEDs, relays, or small solenoids from 3.3 V or 5 V GPIO pins in PLC I/O modules. IC Role / Device Role / Timing Role: Saturated switch with base resistor limiting IB to ensure full turn-on. Use Value: 600 mV max VCE(sat) at 100 mA guarantees <100 mW conduction loss and avoids thermal runaway. |
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 |
|---|---|---|---|
| BC549CTA | Same die, TO-92 ammo pack; no tape-and-reel carrier; identical electrical specs and pinout. | Preferred for manual prototyping or low-volume assembly where reel handling is unnecessary. | Select BC549CTA when automated pick-and-place is not required and bulk handling suffices. |
| MMBT3904LT1G | SMT SOT-23 package; higher fT (300 MHz vs. 300 MHz nominal); slightly higher VCEO (40 V); same hFE Class C range. | Used where board space is constrained and reflow soldering is standard; not mechanically interchangeable. | Choose MMBT3904LT1G for new SMT designs needing footprint reduction; avoid for through-hole retrofits. |
Compared with BC549BTFR, BC549CTA offers identical performance in a different packaging format, while MMBT3904LT1G provides surface-mount compatibility and marginally improved voltage rating-but requires PCB redesign and lacks TO-92 mechanical fit.
Availability
BC549BTFR is available at Aetrix Electronics and suitable for audio preamplification, sensor signal conditioning, and discrete linear regulator applications requiring stable component supply, long-term obsolescence management, and traceable sourcing.
Supply support for BC549BTFR 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, analog, sensor, and connectivity solutions for automotive, industrial, cloud, and consumer markets.
The BC549BTFR belongs to ON Semiconductor's legacy general-purpose bipolar transistor product line, originally developed by Fairchild and maintained for backward-compatible analog designs requiring proven reliability and wide temperature operation.
FAQ
What is the pin configuration of BC549BTFR?
The BC549BTFR uses a standard TO-92 package with pin 1 = Collector, pin 2 = Base, pin 3 = Emitter when viewed from the flat side with leads pointing downward. This configuration is consistent across the BC546–BC550 family and verified in Fairchild's original datasheet Rev. 1.1.1, Figure 7 and 8.
Is BC549BTFR suitable for low-noise audio applications?
Yes, BC549BTFR is explicitly characterized for low-noise operation with a noise figure of 1.4–4.0 dB at 30–15,000 Hz under VCE = 5 V, IC = 200 µA, and RG = 2 kΩ. This makes BC549BTFR appropriate for microphone preamplifiers, phono stages, and other high-SNR analog signal chains where discrete transistor noise dominates.
What hFE classification does BC549BTFR have?
BC549BTFR is a Class C device, with DC current gain (hFE) specified from 420 to 800 at VCE = 5 V and IC = 2 mA. This classification is confirmed in the "hFE Classification" table on page 2 of the BC546–BC550 datasheet Rev. 1.1.1 and applies specifically to BC549 and BC550 variants.
Can BC549BTFR replace BC547B in an existing design?
BC549BTFR is not a direct functional replacement for BC547B due to differences in noise figure (BC547B: 2.0–10.0 dB vs. BC549BTFR: 1.4–4.0 dB) and VCEO (BC547B: 45 V vs. BC549BTFR: 30 V). While pinout and package match, BC549BTFR must be validated for voltage margin and noise-critical roles before substitution in BC547B-based circuits.
What is the maximum power dissipation of BC549BTFR?
The BC549BTFR has a maximum collector power dissipation (PC) of 500 mW at TA = 25 °C, derated linearly above 25 °C per the datasheet's thermal resistance specification. This value is defined under free-air conditions and assumes proper PCB copper area for heat spreading; actual usable power depends on ambient temperature and layout.
BC549BTFR 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
BC549BTFR FAQ
1.How can I place an order for BC549BTFR through Aetrix?
Please submit a Request for Quotation (RFQ) for BC549BTFR 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 BC549BTFR reliable?
The price and inventory of BC549BTFR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BC549BTFR is usually 5 days.
3.What payment methods are accepted for BC549BTFR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BC549BTFR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for BC549BTFR?
BC549BTFR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your BC549BTFR 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 BC549BTFR?
For technical support, including BC549BTFR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BC549BTFR requirements.
6.How does Aetrix verify that BC549BTFR is sourced from the original manufacturer or authorized distributors?
All BC549BTFR 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 BC549BTFR meets industry standards.
7.What is the process for return or replacement of BC549BTFR?
All BC549BTFR units undergo pre-shipment inspection (PSI). If there is an issue with BC549BTFR, 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 BC549BTFR part is unused and in its original packaging.
Return procedure for BC549BTFR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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