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

onsemi BC239C

Name: BC239C
Brand: onsemi
SKU: BC239C
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: BC239C

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

Package:: TO-226-3, TO-92-3 Long Body

Datasheet:: BC239C.pdf

Description:: TRANS NPN 25V 0.1A TO92

Quantity:: RFQ Add To RFQ list

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Product details

Overview

BC239C from ON Semiconductor is an NPN silicon small-signal amplifier transistor in TO-92 package, rated for V_CEO = 25 V, I_C = 100 mA, P_D = 350 mW at T_A = 25°C, with h_FE = 200–500 (at I_C = 2 mA), and f_T = 140–280 MHz - used in low-noise audio preamplifier stages and RF oscillator circuits.

For engineers reviewing the BC239C datasheet, pinout, applications, or equivalent options, key selection criteria include its guaranteed h_FE binning (C suffix), low noise figure (NF = 2.0 dB at 1 kHz), tight V_CE(sat) (≤0.2 V at I_C/I_B = 10), and TO-92 thermal resistance (R_JA = 357°C/W).

Technical Context

The BC239C operates as a general-purpose NPN bipolar junction transistor optimized for linear amplification rather than switching, with specified DC current gain across three collector current ranges (0.2 mA, 2 mA, and 100 mA) and validated f_T performance up to 280 MHz under defined bias conditions.

Its electrical behavior is characterized by low base-emitter saturation voltage (V_BE(sat) ≤ 0.83 V at I_C/I_B = 10), low collector cutoff current (I_CES ≤ 0.2 nA at V_CE = 50 V), and controlled capacitance values (C_obo = 4.5 pF, C_ibo = 8.0 pF), supporting stable high-frequency small-signal operation.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	25 V - Maximum safe collector-emitter voltage before breakdown in common-emitter configuration.
I_C (max)	100 mA - Continuous collector current limit defining linear operating range and power handling.
h_FE	200–500 - Guaranteed DC current gain range at I_C = 2 mA, V_CE = 5 V, enabling predictable bias design.
f_T	140–280 MHz - Transition frequency confirming usable bandwidth for VHF amplification and oscillator design.
NF	2.0 dB - Noise figure at 1 kHz, 0.2 mA, indicating suitability for low-noise preamplifier front-ends.
R_JA	357°C/W - Junction-to-ambient thermal resistance in TO-92 package, defining self-heating under continuous operation.
V_CE(sat)	≤0.2 V - Saturation voltage at I_C/I_B = 10, ensuring minimal voltage drop in active-linear region use cases.

Pinout & Package

BC239C is housed in a TO-92 (Case 29-11, Style 17) plastic package with standard lead configuration and Pb-free plating option available.

Pin/Terminal	Circuit Role	Design Meaning
1	Collector	Main current output terminal; connected to load or next stage input; requires heat-aware PCB layout due to R_JA = 357°C/W.
2	Base	Control electrode; bias current determines collector current via h_FE; low impedance path critical for stability at >100 MHz.
3	Emitter	Current return path; often grounded or decoupled; defines reference for V_BE and V_CE measurements.

Key Features

Feature	Design Value
Guaranteed h_FE binning (C suffix)	h_FE = 200–500 at I_C = 2 mA, enabling consistent gain matching in multi-stage analog designs.
Low noise figure	NF = 2.0 dB at 1 kHz, supporting high-SNR signal conditioning in microphone and sensor interface circuits.
High f_T performance	f_T ≥ 140 MHz ensures reliable operation in 27 MHz CB radio amplifiers and 100 MHz IF stages.
TO-92 thermal profile	R_JA = 357°C/W allows direct replacement of legacy BC109/BC549 without heatsink in <150 mW applications.

Applications

Audio Preamp Stage	RF Oscillator Core
Use Scenario: First amplification stage in electret microphone biasing circuit with 2.2 kΩ collector load and 10 μF coupling. IC Role / Device Role / Timing Role: Small-signal NPN amplifier providing 30–40 dB voltage gain with minimal added noise. Use Value: NF = 2.0 dB and h_FE ≥ 200 ensure clean signal capture before op-amp buffering, preserving SNR in portable voice recorders.	Use Scenario: Colpitts oscillator generating 27 MHz carrier for short-range telemetry transmitters. IC Role / Device Role / Timing Role: Active device sustaining oscillation via tuned LC tank and capacitive feedback network. Use Value: f_T ≥ 140 MHz and low C_obo (4.5 pF) support stable oscillation with minimal phase drift over temperature.
DC-Coupled Sensor Interface	Low-Power Signal Switch
Use Scenario: Amplifying thermistor bridge output in battery-powered environmental monitor with rail-to-rail supply (3.3 V). IC Role / Device Role / Timing Role: Linear amplifier operating in Class-A with emitter degeneration for offset stability. Use Value: V_CEO = 25 V and V_CE(sat) ≤ 0.2 V allow full swing into 3.3 V rails while maintaining linearity at I_C < 1 mA.	Use Scenario: Enabling/disabling 5 V logic-level LED driver using microcontroller GPIO (3.3 V output). IC Role / Device Role / Timing Role: Low-gain switch with forced β = 10 to ensure saturation under marginal drive conditions. Use Value: Guaranteed h_FE ≥ 200 ensures reliable turn-on with 330 Ω base resistor and 3.3 V drive, minimizing power loss in standby.

Audio Preamp Stage

RF Oscillator Core

Use Scenario: First amplification stage in electret microphone biasing circuit with 2.2 kΩ collector load and 10 μF coupling.

IC Role / Device Role / Timing Role: Small-signal NPN amplifier providing 30–40 dB voltage gain with minimal added noise.

Use Value: NF = 2.0 dB and h_FE ≥ 200 ensure clean signal capture before op-amp buffering, preserving SNR in portable voice recorders.

Use Scenario: Colpitts oscillator generating 27 MHz carrier for short-range telemetry transmitters.

IC Role / Device Role / Timing Role: Active device sustaining oscillation via tuned LC tank and capacitive feedback network.

Use Value: f_T ≥ 140 MHz and low C_obo (4.5 pF) support stable oscillation with minimal phase drift over temperature.

DC-Coupled Sensor Interface

Low-Power Signal Switch

Use Scenario: Amplifying thermistor bridge output in battery-powered environmental monitor with rail-to-rail supply (3.3 V).

IC Role / Device Role / Timing Role: Linear amplifier operating in Class-A with emitter degeneration for offset stability.

Use Value: V_CEO = 25 V and V_CE(sat) ≤ 0.2 V allow full swing into 3.3 V rails while maintaining linearity at I_C < 1 mA.

Use Scenario: Enabling/disabling 5 V logic-level LED driver using microcontroller GPIO (3.3 V output).

IC Role / Device Role / Timing Role: Low-gain switch with forced β = 10 to ensure saturation under marginal drive conditions.

Use Value: Guaranteed h_FE ≥ 200 ensures reliable turn-on with 330 Ω base resistor and 3.3 V drive, minimizing power loss in standby.

Equivalent & Alternatives

The following parts are listed as comparable options for similar NPN small-signal amplifier applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
BC549C	Same h_FE bin (200–450), higher V_CEO = 30 V, lower NF = 1.8 dB, identical TO-92 package.	Preferred for 30 V systems or ultra-low-noise preamps; not qualified for >125°C ambient.	Select BC549C when higher breakdown voltage or marginally lower noise is required; verify thermal derating at >100°C.
2N3904	Lower h_FE range (100–300), same V_CEO = 40 V, higher f_T = 300 MHz, identical pinout and package.	Better for high-speed switching or wideband amplification; less suitable for low-noise audio where h_FE consistency matters.	Choose 2N3904 for digital interface or RF buffer roles; avoid in gain-critical analog stages requiring h_FE ≥ 200.

Compared with BC549C and 2N3904, BC239C offers tighter h_FE control and proven thermal stability up to +150°C, making it preferred for industrial-grade audio and oscillator designs where parameter consistency across temperature is critical.

Availability

BC239C is available at Aetrix Electronics and suitable for audio preamplifier stages, RF oscillator cores, DC-coupled sensor interfaces, and low-power signal switching applications requiring stable component supply and long-term manufacturability.

Supply support for BC239C 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 (now onsemi) is a global semiconductor supplier specializing in energy-efficient power management, analog, sensing, and connectivity solutions for automotive, industrial, and consumer markets.

The BC239C belongs to the BC237/BC239 family of general-purpose NPN transistors designed for cost-sensitive, high-reliability linear amplification in industrial and communications equipment.

FAQ

What is the maximum collector-emitter voltage rating for BC239C?

The BC239C has a maximum collector-emitter voltage (V_CEO) rating of 25 V DC. This value is specified under test condition I_C = 2.0 mA and I_B = 0, and must not be exceeded to prevent avalanche breakdown. Derating is required above 25°C ambient per the 2.8 mW/°C thermal coefficient shown in the datasheet. The BC239C datasheet confirms this rating applies specifically to the BC239 variant, distinguishing it from the BC237's 45 V rating.

Does BC239C have a guaranteed h_FE range, and how is it binned?

Yes, the BC239C carries the "C" suffix to indicate guaranteed DC current gain (h_FE) of 200–500 at I_C = 2.0 mA and V_CE = 5.0 V. This binning is verified during final test and distinguishes it from BC239B (120–270) and BC239 (80–300). The BC239C datasheet explicitly lists this range in the "ON CHARACTERISTICS" table, confirming its use in gain-critical analog circuits where consistency matters.

What is the noise figure of BC239C, and under what conditions is it measured?

The BC239C has a noise figure (NF) of 2.0 dB, measured at I_C = 0.2 mA, V_CE = 5.0 V, R_S = 2.0 kΩ, and f = 1.0 kHz. This value is confirmed in the "DYNAMIC CHARACTERISTICS" section of the BC239C datasheet and reflects its suitability for low-noise audio preamplifier applications. It is not specified at higher frequencies or bias points, and no alternate NF value is provided for f = 200 Hz or other conditions.

Is BC239C available in Pb-free packaging, and how is it marked?

Yes, BC239C is available in Pb-free packaging, designated by the "G" suffix (e.g., BC239CG). Per the BC239C datasheet, Pb-free versions comply with JEDEC J-STD-020 moisture sensitivity level 1 and are marked with a microdot identifier on the package body. The marking diagram in the datasheet shows "BC239C" followed by date code and assembly location, with no additional Pb-free symbol required beyond the "G" in the orderable part number.

What is the thermal resistance (R_JA) of BC239C in its TO-92 package?

The BC239C has a junction-to-ambient thermal resistance (R_JA) of 357°C/W when mounted on a standard FR-4 PCB with no copper pour. This value is listed in the "THERMAL CHARACTERISTICS" table of the BC239C datasheet and applies to the TO-92 (Case 29-11) package. It assumes natural convection only; adding thermal relief or copper area reduces effective R_JA, but the datasheet does not provide derated values for enhanced layouts.

BC239C Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

Package/Case:: TO-226-3, TO-92-3 Long Body

Packaging:: Bulk

Product Status:: Obsolete

Transistor Type:: NPN

Current - Collector (Ic) (Max):: 100 mA

Voltage - Collector Emitter Breakdown (Max):: 25 V

Vce Saturation (Max) @ Ib, Ic:: 600mV @ 5mA, 100mA

Current - Collector Cutoff (Max):: 15nA

DC Current Gain (hFE) (Min) @ Ic, Vce:: 380 @ 2mA, 5V

Power - Max:: 350 mW

Frequency - Transition:: 280MHz

Operating Temperature:: -55°C ~ 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-92 (TO-226)

BC239C FAQ

1.How can I place an order for BC239C through Aetrix?

Please submit a Request for Quotation (RFQ) for BC239C 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 BC239C reliable?

The price and inventory of BC239C are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BC239C is usually 5 days.

3.What payment methods are accepted for BC239C?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BC239C transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for BC239C?

BC239C orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your BC239C 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 BC239C?

For technical support, including BC239C datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BC239C requirements.

6.How does Aetrix verify that BC239C is sourced from the original manufacturer or authorized distributors?

All BC239C 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 BC239C meets industry standards.

7.What is the process for return or replacement of BC239C?

All BC239C units undergo pre-shipment inspection (PSI). If there is an issue with BC239C, 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 BC239C part is unused and in its original packaging.

Return procedure for BC239C:

1.Submit a request within 90 days.

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

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