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onsemi BC550ABU
- Part No.:
- BC550ABU
- Manufacturer:
- onsemi
- Category:
- Single Bipolar Transistors
- Package:
- TO-226-3, TO-92-3 (TO-226AA)
- Datasheet:
-
BC550ABU.pdf
- Description:
- TRANS NPN 45V 0.1A TO-92-3
- Quantity:
- Payment:
- Shipping:
Inventory:7,176
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Product details
Overview
BC550ABU from ON Semiconductor is a low-noise NPN epitaxial silicon transistor in TO-92 package, rated for VCEO = 45 V, IC = 100 mA, and hFE = 110–220 (Class A), with fT = 300 MHz and NF = 1.4–3.0 dB - used in audio preamplifier stages and signal conditioning circuits where noise performance is critical.
For engineers reviewing the BC550ABU datasheet, pinout, applications, or equivalent options, key selection criteria include verified low-noise operation at 200 µA/5 V, TO-92 mechanical compatibility, hFE classification consistency, and absence of integrated biasing or protection circuitry.
Technical Context
This device operates as a discrete bipolar junction transistor with fixed emitter-base and collector-base junction geometry optimized for linear amplification. Its low-noise design targets 1–15 kHz audio bandwidths, with specified noise figure measured at VCE = 5 V, IC = 200 µA, RG = 2 kΩ, and frequency range up to 15 kHz.
The BC550ABU belongs to the BC546–BC550 family sharing identical TO-92 packaging, pinout (C-B-E), and absolute maximum ratings except for VCBO/VCEO and noise performance. It is explicitly designated as low-noise (vs. BC546/BC547), and complements BC556–BC560 PNP devices.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCEO | 45 V - supports rail voltages up to ±22.5 V in dual-supply amplifier stages without breakdown |
| hFE Class | A (110–220) - ensures predictable DC bias stability in common-emitter gain stages with moderate gain tolerance |
| fT | 300 MHz - enables stable small-signal amplification up to mid-VHF range, sufficient for IF and wideband audio |
| Noise Figure | 1.4–3.0 dB @ 1–15 kHz - meets low-noise requirements for microphone preamps and sensor front-ends |
| PC | 500 mW - allows continuous operation at 100 mA/5 V without heatsinking in ambient PCB layouts |
| VEBO | 5 V - limits base drive voltage swing to prevent emitter-base junction avalanche in high-gain configurations |
Pinout & Package
BC550ABU uses the standard TO-92 3-lead plastic package with straight leads (bulk packing). Dimensions conform to JEDEC TO-92 specifications; lead spacing is 0.2 inch (5.08 mm).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (Top View) | Collector | Main current sink node; connects to load resistor or next stage input; requires thermal relief on PCB if dissipating >200 mW |
| 2 (Center) | Base | Control terminal for current amplification; sensitive to ESD; requires series resistor to limit IB in switching use |
| 3 (Bottom) | Emitter | Current source node; typically tied to ground or negative rail; forms reference for VBE bias network |
Key Features
| Feature | Design Value |
|---|---|
| Low-noise operation | Verified NF = 1.4–3.0 dB at 200 µA/5 V/2 kΩ source impedance - directly reduces audible hiss in analog signal chains |
| TO-92 mechanical standardization | JEDEC-compliant footprint enables drop-in replacement across BC546–BC550 family and legacy Fairchild/ON parts |
| hFE classification (Class A) | Guaranteed 110–220 hFE range - simplifies bias network design without need for trimming or feedback adjustment |
| Complementary PNP pairing | Designed as NPN counterpart to BC556–BC560 series - supports matched differential pair and push-pull output stage implementation |
Applications
| Microphone Preamp Stage | Instrumentation Signal Conditioning |
|---|---|
Use Scenario: Amplifying weak AC-coupled signals from electret condenser microphones in portable voice recorders. IC Role / Device Role / Timing Role: Discrete NPN transconductance amplifier operating in common-emitter configuration with emitter degeneration. Use Value: Low 1.4–3.0 dB noise figure preserves SNR of sub-10 mVRMS inputs without requiring chopper-stabilized ICs. | Use Scenario: Buffering and gain-setting for thermocouple or strain gauge bridge outputs in industrial data loggers. IC Role / Device Role / Timing Role: First-stage low-noise amplifier with DC-coupled input and adjustable gain via collector resistor. Use Value: Stable hFE Class A (110–220) enables predictable gain calibration across temperature without active trimming. |
| Audio Tone Control Circuit | Discrete RF Detector Front-End |
Use Scenario: Implementing passive tone stack (bass/treble) with active buffering in guitar effects pedals. IC Role / Device Role / Timing Role: Unity-gain emitter follower providing high-input / low-output impedance isolation between filter sections. Use Value: 300 MHz fT ensures flat response through 20 kHz with <0.1 dB deviation, preserving tonal fidelity. | Use Scenario: Envelope detection of 10–50 MHz RF carriers in low-cost AM receiver modules. IC Role / Device Role / Timing Role: Base-driven detector diode replacement using forward-biased BE junction with collector open. Use Value: Verified VBE(on) = 580–700 mV at 2 mA ensures consistent turn-on threshold across production lots. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar low-noise NPN transistor applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| BC549BTA | Same family, Class B hFE (200–450); identical noise spec (1.4–4.0 dB); TO-92 ammo pack | Higher hFE enables lower base drive current but increases sensitivity to thermal drift in bias networks | Select when higher DC gain is needed without changing layout or thermal design |
| 2N5088 | Higher VCEO = 30 V (vs. BC550ABU's 45 V); NF = 1.0 dB typical; TO-92, same pinout | Optimized for ultra-low-noise <1 kHz applications (e.g., phono preamps); lower max voltage limits supply headroom | Select when sub-1 dB noise dominates over voltage margin, and supply rails ≤ ±15 V |
Compared with BC550ABU, BC549BTA offers higher hFE at identical noise and voltage ratings, while 2N5088 trades 15 V lower VCEO for marginally better low-frequency noise - both require verification of bias point stability under target operating conditions.
Availability
BC550ABU is available at Aetrix Electronics and suitable for audio preamplifiers, instrumentation signal conditioning, and discrete RF detector front-ends requiring stable component supply and traceable sourcing.
Supply support for BC550ABU 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, sensors, and discrete devices for automotive, industrial, and consumer markets.
The BC550ABU belongs to ON Semiconductor's legacy general-purpose transistor product line, designed for cost-sensitive, high-reliability linear and switching applications in audio, sensing, and interface circuits.
FAQ
What is the maximum collector-emitter voltage rating for BC550ABU?
The BC550ABU has a guaranteed VCEO rating of 45 V at TA = 25°C. This rating applies under DC conditions with no secondary breakdown limitations. Operation above this voltage risks permanent junction damage, and derating is required above 25°C per the datasheet's thermal curves. The BC550ABU must not be substituted for BC546-series parts in 65 V applications.
Does BC550ABU have a specified noise figure, and under what conditions?
Yes, BC550ABU has a noise figure of 1.4–3.0 dB, measured at VCE = 5 V, IC = 200 µA, RG = 2 kΩ, and frequencies from 30 Hz to 15 kHz. This specification distinguishes it from BC546/BC547 variants and confirms its suitability for low-noise analog front-ends. The BC550ABU's noise performance is validated per the original Fairchild/ON Semiconductor characterization methodology.
What is the hFE classification of BC550ABU, and how does it affect circuit design?
The BC550ABU is classified as Class A, with hFE ranging from 110 to 220 at VCE = 5 V and IC = 2 mA. This bounded gain range allows predictable bias point calculation in common-emitter amplifiers without iterative trimming. Designers can rely on BC550ABU's hFE spread to remain within ±20% of nominal values across production lots, reducing calibration overhead in volume manufacturing.
Is BC550ABU pin-compatible with other BC5xx transistors?
Yes, BC550ABU uses the standard TO-92 package with Collector–Base–Emitter pinout (1–2–3, top view), matching all BC546–BC550 variants and complementary BC556–BC560 PNP devices. Mechanical and electrical pin compatibility is confirmed by JEDEC TO-92 compliance and shared ordering documentation. No PCB layout change is required when substituting within the BC5xx family, provided voltage and noise requirements align.
Can BC550ABU be used in switching applications?
BC550ABU is characterized for both switching and amplification per its official features list, with VCE(sat) = 90–250 mV at IC = 10 mA/IB = 0.5 mA and 250–600 mV at IC = 100 mA/IB = 5 mA. However, its primary design emphasis is low-noise linear operation; for high-speed or high-current switching, dedicated switching transistors like BC337 offer superior saturation characteristics and faster recovery.
BC550ABU Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- -
- Package/Case:
- TO-226-3, TO-92-3 (TO-226AA)
- Packaging:
- Bulk
- 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:
- 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
BC550ABU FAQ
1.How can I place an order for BC550ABU through Aetrix?
Please submit a Request for Quotation (RFQ) for BC550ABU 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 BC550ABU reliable?
The price and inventory of BC550ABU are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BC550ABU is usually 5 days.
3.What payment methods are accepted for BC550ABU?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BC550ABU transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for BC550ABU?
BC550ABU orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your BC550ABU 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 BC550ABU?
For technical support, including BC550ABU datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BC550ABU requirements.
6.How does Aetrix verify that BC550ABU is sourced from the original manufacturer or authorized distributors?
All BC550ABU 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 BC550ABU meets industry standards.
7.What is the process for return or replacement of BC550ABU?
All BC550ABU units undergo pre-shipment inspection (PSI). If there is an issue with BC550ABU, 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 BC550ABU part is unused and in its original packaging.
Return procedure for BC550ABU:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
BC550ABU Tags
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