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

NXP Semiconductors BC550C,112

Name: BC550C,112
Brand: NXP Semiconductors
SKU: BC550C,112
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: BC550C,112

Manufacturer:: NXP Semiconductors

Category:: Single Bipolar Transistors

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

Datasheet:: BC550C,112.pdf

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

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Product details

Overview

BC550C,112 from NXP Semiconductors is an NPN general-purpose bipolar junction transistor in TO-92 (SOT54) package, rated for V_CEO = 45 V, I_C = 100 mA, and h_FE = 420–800 at I_C = 2 mA, used in low-noise audio preamplifier stages and signal amplification circuits.

For engineers reviewing the BC550C,112 datasheet, BC550C,112 pinout, BC550C,112 application, or BC550C,112 equivalent, key selection criteria include DC current gain spread, V_CEsat at defined drive conditions, thermal resistance (R_th(j-a) = 250 K/W), noise figure (≤4 dB), and TO-92 mechanical compatibility.

Technical Context

The BC550C,112 operates as a linear amplifying device with fixed-emitter biasing capability, supporting Class-A small-signal amplification where low base-emitter voltage drift (−2 mV/K) and stable h_FE across I_C = 10 μA to 100 mA are critical. Its f_T of 100 MHz enables operation up to mid-audio frequencies without gain roll-off.

Designed for through-hole mounting on FR4 PCBs, it exhibits R_th(j-a) = 250 K/W under standard conditions and maintains V_BE = 580–700 mV at I_C = 2 mA, enabling predictable bias point setting in discrete amplifier topologies.

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 rails.
I_C (DC)	100 mA - Continuous collector current limit; sets upper bound for quiescent bias and output swing capability.
h_FE	420–800 @ I_C = 2 mA - DC current gain spread determines bias stability and stage gain predictability in linear amplifiers.
V_CEsat	90–250 mV @ I_C = 10 mA / I_B = 0.5 mA - Low saturation voltage minimizes power loss and improves efficiency in switching or saturated-stage designs.
f_T	100 MHz - Transition frequency confirms usable bandwidth up to ~10 MHz for small-signal amplification with adequate gain margin.
F (Noise)	≤4 dB @ 1 kHz, 200 μA, 2 kΩ source - Confirmed low-noise performance suitable for microphone preamp and phono-stage inputs.
R_th(j-a)	250 K/W - Thermal resistance value used to calculate junction temperature rise under ambient-limited dissipation (P_tot = 500 mW).

Pinout & Package

BC550C,112 is housed in a plastic single-ended leaded (through-hole) TO-92 package (SOT54, SC-43A), with 3 leads spaced at 2.54 mm pitch and overall dimensions of 4.8 × 4.2 × 14.5 mm (D × E × L).

Pin/Terminal	Circuit Role	Design Meaning
1	Emitter	Reference terminal for bias network; connects to ground or emitter degeneration resistor in common-emitter configuration.
2	Base	Control input node; requires current-limited drive (I_B ≤ 200 mA peak) to avoid damage or nonlinear distortion.
3	Collector	Output node carrying amplified current; connects to load resistor or next-stage input in multi-stage amplifiers.

Key Features

Feature	Design Value
Low-noise operation	Verified noise figure ≤4 dB at 1 kHz supports high-fidelity audio front-end design without added filtering.
Wide h_FE range	420–800 at I_C = 2 mA enables consistent gain across production lots when paired with emitter feedback.
Stable V_BE vs. temperature	Drift of −2 mV/K allows accurate thermal compensation in bias networks using matched transistors or diodes.
TO-92 mechanical standardization	Compatible with legacy through-hole assembly tooling and hand-soldering workflows without adapter requirements.

Applications

Microphone Preamplifier	Audio Tone Control Stage
Use Scenario: Amplifying weak electret microphone signals (1–10 mV) before ADC or active filter stages. IC Role / Device Role / Timing Role: NPN small-signal amplifier in common-emitter configuration with emitter degeneration. Use Value: Low 4 dB noise figure and stable h_FE ensure high SNR and repeatable gain without trimming resistors.	Use Scenario: Implementing passive/active tone-shaping networks in consumer audio equipment. IC Role / Device Role / Timing Role: Discrete gain block with adjustable Q and center frequency via RC feedback. Use Value: 100 MHz f_T and low V_CEsat preserve harmonic integrity up to 15 kHz while minimizing distortion at mid-band frequencies.
LED Driver Switch	Signal Level Shifter
Use Scenario: Driving indicator LEDs from microcontroller GPIO pins with current limiting. IC Role / Device Role / Timing Role: Saturated switch controlling LED anode/cathode current path. Use Value: 90–250 mV V_CEsat ensures minimal voltage drop and predictable LED brightness across supply variations.	Use Scenario: Translating logic levels between 3.3 V MCU outputs and 5 V analog circuitry. IC Role / Device Role / Timing Role: Common-emitter level translator with base resistor biasing. Use Value: Defined V_BE (580–700 mV) and h_FE enable deterministic threshold and fast edge response without external hysteresis.

Microphone Preamplifier

Audio Tone Control Stage

Use Scenario: Amplifying weak electret microphone signals (1–10 mV) before ADC or active filter stages.

IC Role / Device Role / Timing Role: NPN small-signal amplifier in common-emitter configuration with emitter degeneration.

Use Value: Low 4 dB noise figure and stable h_FE ensure high SNR and repeatable gain without trimming resistors.

Use Scenario: Implementing passive/active tone-shaping networks in consumer audio equipment.

IC Role / Device Role / Timing Role: Discrete gain block with adjustable Q and center frequency via RC feedback.

Use Value: 100 MHz f_T and low V_CEsat preserve harmonic integrity up to 15 kHz while minimizing distortion at mid-band frequencies.

LED Driver Switch

Signal Level Shifter

Use Scenario: Driving indicator LEDs from microcontroller GPIO pins with current limiting.

IC Role / Device Role / Timing Role: Saturated switch controlling LED anode/cathode current path.

Use Value: 90–250 mV V_CEsat ensures minimal voltage drop and predictable LED brightness across supply variations.

Use Scenario: Translating logic levels between 3.3 V MCU outputs and 5 V analog circuitry.

IC Role / Device Role / Timing Role: Common-emitter level translator with base resistor biasing.

Use Value: Defined V_BE (580–700 mV) and h_FE enable deterministic threshold and fast edge response without external hysteresis.

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
BC549C,112	V_CEO = 30 V (vs. 45 V); h_FE min = 270 at I_C = 10 μA; otherwise identical package and pinout.	Lower voltage rating restricts use in higher-rail audio supplies (>30 V) and limits headroom in Class-A stages.	Select BC549C,112 only when supply voltage is ≤30 V and lower h_FE tolerance is acceptable.
2N3904,113	V_CEO = 40 V; h_FE = 100–300 @ I_C = 10 mA; R_th(j-a) = 200 K/W; slightly lower noise (F ≈ 3 dB).	Narrower h_FE range reduces gain variability but requires tighter bias design; better thermal performance suits higher ambient environments.	Choose 2N3904,113 when thermal margin is constrained or when tighter h_FE control outweighs need for ultra-low noise.

Compared with BC550C,112, BC549C,112 offers reduced voltage headroom but identical footprint, while 2N3904,113 trades h_FE spread for improved thermal resistance and marginally lower noise-making each suitable for distinct bias stability, supply, and thermal requirements.

Availability

BC550C,112 is available at Aetrix Electronics and suitable for audio preamplifiers, LED driver circuits, signal level shifters, and discrete amplifier modules requiring stable component supply and long-term obsolescence management.

Supply support for BC550C,112 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

NXP Semiconductors is a global semiconductor company headquartered in Eindhoven, Netherlands, specializing in secure connectivity solutions, automotive electronics, and analog/mixed-signal components.

The BC550C,112 belongs to NXP's legacy general-purpose transistor product line, designed specifically for cost-sensitive, high-reliability discrete amplifier and switching applications in consumer audio, industrial controls, and educational electronics.

FAQ

What is the maximum collector-emitter voltage rating for BC550C,112?

The BC550C,112 has a maximum collector-emitter voltage (V_CEO) rating of 45 V under open-base conditions, as specified in the Absolute Maximum Ratings table of the NXP product data sheet dated 2004 Oct 11. This rating defines the upper limit for safe DC operation in common-emitter configurations and must not be exceeded to prevent avalanche breakdown or permanent device failure. Derating is recommended above Tamb = 25 °C.

Does BC550C,112 have a guaranteed minimum h_FE at I_C = 2 mA?

Yes, BC550C,112 guarantees a minimum h_FE of 420 at V_CE = 5 V and I_C = 2 mA, with a typical value of 520 and maximum of 800. This specification is confirmed in the "CHARACTERISTICS" section of the official NXP datasheet and supports reliable bias point design in linear amplifier stages without requiring gain binning or manual selection.

Is BC550C,112 suitable for low-noise audio applications?

Yes, BC550C,112 is explicitly characterized for low-noise operation with a maximum noise figure (F) of 4 dB at 1 kHz, 200 μA collector current, and 2 kΩ source resistance. This performance is validated in the NXP datasheet and makes BC550C,112 appropriate for microphone preamplifiers, phono stages, and other sensitive analog front-ends where signal integrity is critical.

What is the thermal resistance from junction to ambient for BC550C,112?

The thermal resistance from junction to ambient (R_th(j-a)) for BC550C,112 is 250 K/W when mounted on an FR4 printed-circuit board, per note 1 in the NXP thermal characteristics table. This value assumes standard through-hole soldering and no heatsinking, and is used to calculate junction temperature rise under given power dissipation (P_tot = 500 mW max at T_amb ≤ 25 °C).

What package type does BC550C,112 use and what are its key mechanical dimensions?

BC550C,112 uses the TO-92 plastic single-ended leaded (through-hole) package, also designated SOT54 or SC-43A. Key dimensions include overall length L = 14.5 mm, body width D = 4.8 mm, body thickness E = 4.2 mm, lead pitch e = 2.54 mm, and lead diameter b = 0.48 mm - all verified in the NXP package outline drawing dated 2004 Oct 11.

BC550C,112 Specifications

Product attributes: Attribute value

Manufacturer:: NXP Semiconductors

Series:: -

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

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:: 420 @ 2mA, 5V

Power - Max:: 500 mW

Frequency - Transition:: 100MHz

Operating Temperature:: 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-92-3

BC550C,112 FAQ

1.How can I place an order for BC550C,112 through Aetrix?

Please submit a Request for Quotation (RFQ) for BC550C,112 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 BC550C,112 reliable?

The price and inventory of BC550C,112 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BC550C,112 is usually 5 days.

3.What payment methods are accepted for BC550C,112?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BC550C,112 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for BC550C,112?

BC550C,112 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your BC550C,112 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 BC550C,112?

For technical support, including BC550C,112 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BC550C,112 requirements.

6.How does Aetrix verify that BC550C,112 is sourced from the original manufacturer or authorized distributors?

All BC550C,112 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 BC550C,112 meets industry standards.

7.What is the process for return or replacement of BC550C,112?

All BC550C,112 units undergo pre-shipment inspection (PSI). If there is an issue with BC550C,112, 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 BC550C,112 part is unused and in its original packaging.

Return procedure for BC550C,112:

1.Submit a request within 90 days.

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

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