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

onsemi BC337BU

Name: BC337BU
Brand: onsemi
SKU: BC337BU
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: BC337BU

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

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

Datasheet:: BC337BU.pdf

Description:: TRANS NPN 45V 0.8A TO-92-3

Quantity:: RFQ Add To RFQ list

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Inventory:3,675

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Product details

Overview

BC337BU from ON Semiconductor is a general-purpose NPN epitaxial silicon transistor in TO-92 package, rated for 45 V V_CEO, 800 mA I_C, and 625 mW P_D, optimized for low-voltage switching and audio-frequency amplification in consumer electronics and industrial control circuits.

For engineers reviewing the BC337BU datasheet, pinout, applications, or equivalent options, key selection criteria include h_FE classification (100–250 at 100 mA), V_CE(sat) ≤ 0.7 V at 500 mA/50 mA drive, f_T = 100 MHz, Cob = 12 pF, and TO-92 mechanical compatibility with legacy through-hole designs.

Technical Context

The BC337BU operates as a discrete bipolar junction transistor with fixed emitter-base and collector-emitter junctions, supporting linear amplification and saturated switching modes. Its h_FE range (100–250) and low V_BE(on) (1.2 V at 300 mA) enable predictable biasing in Class-A amplifiers and digital logic interface stages.

Thermal performance is defined by R_θJA = 200 °C/W on standard FR-4 PCB, with derating of 5.0 mW/°C above 25 °C ambient. Absolute maximum ratings include T_J = 150 °C and T_STG = –55 to 150 °C, confirming suitability for non-automotive industrial environments.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	45 V - Maximum safe collector-emitter voltage before breakdown under open-base conditions; sets upper rail limit in 24–36 V DC systems.
I_C (DC)	800 mA - Continuous collector current handling capacity; supports relay drivers and small-signal power stages up to ~300 mW output.
P_D	625 mW - Total dissipation at 25 °C ambient; requires thermal derating above 25 °C per 5.0 mW/°C slope.
h_FE (100 mA)	100–250 - DC current gain at V_CE = 1 V, defining base drive requirements for reliable saturation in switch applications.
f_T	100 MHz - Transition frequency at V_CE = 5 V, IC = 10 mA; enables stable operation up to mid-audio frequencies (~10–20 kHz).
C_ob	12 pF - Output capacitance at V_CB = 10 V; impacts high-frequency response and switching speed in fast-switching configurations.

Pinout & Package

BC337BU uses the JEDEC-standard TO-92 3-lead plastic package with straight leads and bulk packing. Pin 1 is Collector, Pin 2 is Base, Pin 3 is Emitter - verified per Fairchild BC337/BC338 Rev. 1.5 datasheet Figure 1.

Pin/Terminal	Circuit Role	Design Meaning
1 (Collector)	Main current sink terminal	Connected to load or supply rail; carries full switched current; requires heatsinking if operating near P_D limit.
2 (Base)	Control input node	Receives forward-biased current to turn on transistor; typical drive is 5–50 mA for full saturation at I_C ≤ 500 mA.
3 (Emitter)	Current return path	Usually grounded or connected to low-side reference; establishes common node for bias network and feedback paths.

Key Features

Feature	Design Value
Switching & amplification dual use	Validated across V_CE = 1 V (linear) and V_CE(sat) ≤ 0.7 V (switching) operating points per datasheet test conditions.
Complementary pairing with BC327	Matched V_CEO, I_C, and h_FE ranges enable push-pull amplifier and H-bridge driver topologies without redesign.
TO-92 mechanical standardization	JEDEC-compliant footprint ensures drop-in replacement in existing through-hole layouts designed for BC107, BC547, or 2N2222A.
AF-driver stage suitability	Specified f_T = 100 MHz and low Cob = 12 pF support distortion-free operation in preamplifier and headphone driver stages up to 20 kHz.

Applications

Audio Preamp Stage	Microcontroller GPIO Driver
Use Scenario: Low-noise voltage amplification of line-level analog signals (e.g., microphone or DAC output) before ADC sampling. IC Role / Device Role / Timing Role: Discrete NPN transistor configured in common-emitter topology with emitter degeneration for gain stability. Use Value: h_FE = 100–250 and V_BE(on) = 1.2 V ensure consistent bias point across temperature; f_T = 100 MHz preserves signal integrity up to 20 kHz.	Use Scenario: Driving LEDs, relays, or small solenoids from 3.3 V or 5 V microcontroller outputs with limited current capability. IC Role / Device Role / Timing Role: Saturated switch controlled by MCU GPIO pin via series base resistor. Use Value: V_CE(sat) ≤ 0.7 V at I_C/I_B = 500 mA/50 mA minimizes power loss; TO-92 package allows manual prototyping and board-level repair.
Low-Power Output Stage	Signal Level Shifting
Use Scenario: Final amplification stage delivering up to 100 mW into 8 Ω speaker loads in portable audio devices. IC Role / Device Role / Timing Role: Class-A or Class-AB emitter-follower output buffer with local feedback. Use Value: P_D = 625 mW and T_J = 150 °C allow continuous operation at 100 mW with minimal heatsinking; h_FE consistency ensures predictable gain compression.	Use Scenario: Translating logic levels between 3.3 V microcontrollers and 5 V peripherals (e.g., UART lines or sensor interfaces). IC Role / Device Role / Timing Role: Common-emitter level translator with pull-up on collector and base driven by low-voltage source. Use Value: V_CEO = 45 V provides margin against transients; low Cob = 12 pF avoids signal edge degradation at 1–10 Mbps data rates.

Audio Preamp Stage

Microcontroller GPIO Driver

Use Scenario: Low-noise voltage amplification of line-level analog signals (e.g., microphone or DAC output) before ADC sampling.

IC Role / Device Role / Timing Role: Discrete NPN transistor configured in common-emitter topology with emitter degeneration for gain stability.

Use Value: h_FE = 100–250 and V_BE(on) = 1.2 V ensure consistent bias point across temperature; f_T = 100 MHz preserves signal integrity up to 20 kHz.

Use Scenario: Driving LEDs, relays, or small solenoids from 3.3 V or 5 V microcontroller outputs with limited current capability.

IC Role / Device Role / Timing Role: Saturated switch controlled by MCU GPIO pin via series base resistor.

Use Value: V_CE(sat) ≤ 0.7 V at I_C/I_B = 500 mA/50 mA minimizes power loss; TO-92 package allows manual prototyping and board-level repair.

Low-Power Output Stage

Signal Level Shifting

Use Scenario: Final amplification stage delivering up to 100 mW into 8 Ω speaker loads in portable audio devices.

IC Role / Device Role / Timing Role: Class-A or Class-AB emitter-follower output buffer with local feedback.

Use Value: P_D = 625 mW and T_J = 150 °C allow continuous operation at 100 mW with minimal heatsinking; h_FE consistency ensures predictable gain compression.

Use Scenario: Translating logic levels between 3.3 V microcontrollers and 5 V peripherals (e.g., UART lines or sensor interfaces).

IC Role / Device Role / Timing Role: Common-emitter level translator with pull-up on collector and base driven by low-voltage source.

Use Value: V_CEO = 45 V provides margin against transients; low Cob = 12 pF avoids signal edge degradation at 1–10 Mbps data rates.

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
BC547B	Higher h_FE (200–450), same V_CEO = 45 V, but lower I_C = 100 mA max; TO-92 package identical.	Not suitable for >100 mA loads; preferred where low base drive and precision gain are prioritized over current handling.	Select BC547B when designing battery-powered sensor interfaces requiring ultra-low base current.
2N2222A	Higher P_D = 800 mW, higher I_C = 800 mA, but wider h_FE spread (100–300); TO-92 compatible pinout.	Supports higher peak currents and slightly better thermal margin; may require revised base resistor values due to h_FE variance.	Select 2N2222A when replacing BC337BU in legacy industrial controls where extended thermal headroom is needed.

Compared with BC547B and 2N2222A, the BC337BU offers a balanced trade-off of current capability (800 mA), gain consistency (100–250), and proven reliability in cost-sensitive consumer audio and logic interfacing-making it optimal for volume production where design reuse and supply chain stability are critical.

Availability

BC337BU is available at Aetrix Electronics and suitable for audio preamplifiers, microcontroller peripheral drivers, and low-power output stages requiring stable component supply and long-term manufacturability.

Supply support for BC337BU 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 management, analog, sensors, and discrete components for automotive, industrial, and consumer markets.

The BC337BU belongs to ON Semiconductor's legacy general-purpose transistor product line, originally developed by Fairchild and maintained for broad compatibility in cost-sensitive, non-safety-critical linear and switching applications.

FAQ

What is the maximum collector-emitter voltage rating for BC337BU?

The BC337BU has a maximum collector-emitter voltage rating (V_CEO) of 45 V under open-base conditions at 25 °C ambient. This rating decreases with rising junction temperature and must be derated per the device's thermal characteristics. Exceeding 45 V risks avalanche breakdown and permanent damage. The BC337BU datasheet specifies this value explicitly in the Absolute Maximum Ratings table.

Is BC337BU pin-compatible with BC547 or 2N2222A?

Yes, the BC337BU uses the standard TO-92 package with Collector-Base-Emitter pinout (1-2-3), matching BC547 and 2N2222A. However, electrical differences exist: BC337BU supports 800 mA I_C versus 100 mA for BC547B and 800 mA for 2N2222A, while h_FE ranges differ. Physical compatibility does not guarantee functional interchangeability without circuit validation.

What is the typical DC current gain (h_FE) of BC337BU at 100 mA collector current?

The BC337BU is classified as "h_FE1 100–250" at V_CE = 1 V and I_C = 100 mA, per the h_FE Classification table in the BC337/BC338 Rev. 1.5 datasheet. This range reflects manufacturing variation and must be accounted for in base bias design-e.g., using worst-case h_FE = 100 to ensure saturation under all conditions.

Can BC337BU be used in audio amplifier circuits?

Yes, the BC337BU is explicitly recommended for AF-driver stages and low-power output stages. Its f_T = 100 MHz, low Cob = 12 pF, and stable h_FE make it suitable for preamplifier gain blocks and Class-A output buffers up to 20 kHz. Designers should verify thermal performance at target output power using R_θJA = 200 °C/W and derating curves.

What packaging options are available for BC337BU?

The BC337BU is supplied in bulk packaging, as indicated in the Ordering Information table of the BC337/BC338 datasheet. Other variants like BC33716TA use ammo or tape-and-reel, but BC337BU specifically denotes bulk-packed TO-92 units-ideal for prototyping, hand-soldering, and low-volume production runs.

BC337BU 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):: 800 mA

Voltage - Collector Emitter Breakdown (Max):: 45 V

Vce Saturation (Max) @ Ib, Ic:: 700mV @ 50mA, 500mA

Current - Collector Cutoff (Max):: 100nA

DC Current Gain (hFE) (Min) @ Ic, Vce:: 100 @ 100mA, 1V

Power - Max:: 625 mW

Frequency - Transition:: 100MHz

Operating Temperature:: 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-92-3

BC337BU FAQ

1.How can I place an order for BC337BU through Aetrix?

Please submit a Request for Quotation (RFQ) for BC337BU 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 BC337BU reliable?

The price and inventory of BC337BU are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BC337BU is usually 5 days.

3.What payment methods are accepted for BC337BU?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BC337BU transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for BC337BU?

BC337BU orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your BC337BU 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 BC337BU?

For technical support, including BC337BU datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BC337BU requirements.

6.How does Aetrix verify that BC337BU is sourced from the original manufacturer or authorized distributors?

All BC337BU 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 BC337BU meets industry standards.

7.What is the process for return or replacement of BC337BU?

All BC337BU units undergo pre-shipment inspection (PSI). If there is an issue with BC337BU, 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 BC337BU part is unused and in its original packaging.

Return procedure for BC337BU:

1.Submit a request within 90 days.

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

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