Send an Inquiry

To receive a quote for your project, please fill in the following information, and we’ll get back to you promptly.

Submit Inventory List

Please fill in the following information, and we’ll get back to you promptly.

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

onsemi BCW66G

Name: BCW66G
Brand: onsemi
SKU: BCW66G
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

Compare

Part No.:: BCW66G

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

Package:: TO-236-3, SC-59, SOT-23-3

Datasheet:: BCW66G.pdf

Description:: TRANS NPN 45V 1A SOT-23-3

Quantity:: RFQ Add To RFQ list

Payment:

Shipping:

Inventory:4,336

Please send an inquiry. Send us your inquiry, and we will respond immediately.

Product details

Overview

BCW66G from ON Semiconductor is an NPN general-purpose bipolar junction transistor (BJT) designed for amplifier and switching applications up to 500 mA collector current. It features a V_CEO of 45 V, V_CBO of 75 V, h_FE ranging from 50 to 400 (depending on bias), f_T of 100 MHz, and SOT-23 surface-mount package - commonly used in low-power audio preamplifiers and signal switching circuits.

For engineers reviewing the BCW66G datasheet, pinout, applications, or equivalent options, key selection considerations include its DC current gain profile across operating currents, saturation voltage at 500 mA, thermal resistance (357 °C/W), noise figure (10 dB at 1 kHz), and compatibility with SOT-23 footprint-constrained PCB layouts.

Technical Context

The BCW66G operates as a silicon NPN BJT with a maximum junction temperature of +150 °C and storage range from –55 °C to +150 °C. Its breakdown voltages (V_CBO = 75 V, V_CEO = 45 V, V_EBO = 5 V) define safe operating limits under reverse-biased conditions. The device uses Fairchild's Process 13, optimized for general-purpose amplification.

Dynamic performance includes f_T = 100 MHz at V_CE = 10 V and I_C = 20 mA, turn-on time of 100 ns, and turn-off time of 400 ns under specified load conditions. Input and output capacitances (C_ibo = 80 pF, C_obo = 12 pF) support mid-frequency small-signal operation without excessive Miller effect.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	45 V - Maximum collector-emitter voltage before avalanche breakdown; sets upper rail limit in common-emitter amplifier stages.
h_FE (I_C = 100 mA)	160 - DC current gain at medium current; enables stable biasing in Class-A preamp designs without excessive base drive.
f_T	100 MHz - Unity-gain bandwidth; supports audio and low-RF amplification up to ~10–20 MHz with usable gain.
V_CE(sat) @ 500 mA	0.7 V - Low saturation voltage at high current; minimizes power loss in switching applications with <1 W dissipation.
R_θJA	357 °C/W - Junction-to-ambient thermal resistance; requires careful copper pour or derating above 25 °C ambient for continuous 350 mW operation.
Package	SOT-23 - Standard 3-pin surface-mount outline; compatible with automated pick-and-place and reflow processes.

Pinout & Package

SOT-23 plastic surface-mount package with gull-wing leads; 1.90 mm × 1.30 mm body size, 0.95 mm height, and 0.95 mm lead pitch. Marking "EG" identifies BCW66G on top surface.

Pin/Terminal	Circuit Role	Design Meaning
1 (Base)	Control electrode	Receives forward-biased current to modulate collector-emitter conduction; requires current-limiting resistor in most bias networks.
2 (Emitter)	Current source terminal	Common reference node in common-emitter configuration; tied to ground or negative rail in amplifier designs.
3 (Collector)	Output current terminal	Delivers amplified/saturated current to load; connected to supply rail via load resistor or active circuitry.

Key Features

Feature	Design Value
NPN silicon BJT	Enables standard emitter-follower, common-emitter, and switch configurations with predictable β and V_BE behavior.
100 MHz f_T	Supports wideband small-signal amplification up to 10–20 MHz with adequate gain margin.
Low V_CE(sat) (0.7 V @ 500 mA)	Reduces conduction loss in digital logic interface and power-switching roles where efficiency matters at sub-amp levels.
10 dB noise figure @ 1 kHz	Meets requirements for low-noise preamplifier stages in sensor signal conditioning and audio front-ends.
SOT-23 footprint	Enables high-density PCB layouts and compatibility with industry-standard assembly equipment and reflow profiles.

Applications

Audio Preamp Stage	LED Driver Switch
Use Scenario: Amplifying weak microphone or piezoelectric sensor signals before ADC sampling in portable instrumentation. IC Role / Device Role / Timing Role: NPN small-signal amplifier in common-emitter configuration with fixed bias or emitter degeneration. Use Value: h_FE ≥ 110 at 10 mA and 10 dB noise figure ensure clean gain without introducing significant self-noise in 20 Hz–20 kHz band.	Use Scenario: Driving discrete LEDs or LED strings in indicator panels and status displays with microcontroller GPIO control. IC Role / Device Role / Timing Role: Low-side saturated switch turning on/off LED current path between ground and load. Use Value: V_CE(sat) ≤ 0.7 V at 500 mA ensures >90% power efficiency in LED current path and minimal self-heating during continuous operation.
Signal Level Shifter	Current Mirror Reference
Use Scenario: Translating logic-level signals between 3.3 V and 5 V domains in mixed-voltage embedded systems. IC Role / Device Role / Timing Role: Common-emitter level translator with pull-up resistor on collector and base driven by lower-voltage source. Use Value: V_CEO = 45 V and fast switching (t_on/t_off = 100/400 ns) allow reliable translation across multiple logic families with minimal propagation delay.	Use Scenario: Providing matched current reference in analog ICs or discrete op-amp bias networks requiring stable I_C replication. IC Role / Device Role / Timing Role: Active element in two-transistor current mirror topology with matched thermal environment. Use Value: Tight h_FE spread (50–400) and low I_CES (20 nA @ 25 °C) support accurate current ratio tracking over temperature and supply variation.

Audio Preamp Stage

LED Driver Switch

Use Scenario: Amplifying weak microphone or piezoelectric sensor signals before ADC sampling in portable instrumentation.

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

Use Value: h_FE ≥ 110 at 10 mA and 10 dB noise figure ensure clean gain without introducing significant self-noise in 20 Hz–20 kHz band.

Use Scenario: Driving discrete LEDs or LED strings in indicator panels and status displays with microcontroller GPIO control.

IC Role / Device Role / Timing Role: Low-side saturated switch turning on/off LED current path between ground and load.

Use Value: V_CE(sat) ≤ 0.7 V at 500 mA ensures >90% power efficiency in LED current path and minimal self-heating during continuous operation.

Signal Level Shifter

Current Mirror Reference

Use Scenario: Translating logic-level signals between 3.3 V and 5 V domains in mixed-voltage embedded systems.

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

Use Value: V_CEO = 45 V and fast switching (t_on/t_off = 100/400 ns) allow reliable translation across multiple logic families with minimal propagation delay.

Use Scenario: Providing matched current reference in analog ICs or discrete op-amp bias networks requiring stable I_C replication.

IC Role / Device Role / Timing Role: Active element in two-transistor current mirror topology with matched thermal environment.

Use Value: Tight h_FE spread (50–400) and low I_CES (20 nA @ 25 °C) support accurate current ratio tracking over temperature and supply variation.

Equivalent & Alternatives

The following parts are listed as comparable options for similar NPN general-purpose amplifier applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
BC847B	Lower max I_C (100 mA vs. 1 A), higher h_FE min (200), same SOT-23 package	Better suited for low-current signal amplification; not rated for 500 mA switching	Select BC847B when gain consistency at µA–mA levels is prioritized over power handling.
MMBT3904	Identical V_CEO/V_CBO, slightly lower f_T (300 MHz typical but 100 MHz guaranteed), same pinout	Widely available alternative with broader qualification history; identical thermal specs	MMBT3904 offers proven reliability in industrial controls where long-term supply continuity is critical.

Compared with BCW66G, BC847B trades peak current capability for tighter h_FE tolerance at low bias, while MMBT3904 provides equivalent voltage ratings and pinout with marginally higher f_T - making it a drop-in candidate where legacy validation exists.

Availability

BCW66G is available at Aetrix Electronics and suitable for audio preamplifiers, LED driver switches, and logic-level translators requiring stable component supply, consistent parametric performance, and SOT-23 footprint compatibility.

Supply support for BCW66G 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, sensing, and connectivity solutions for automotive, industrial, cloud, and consumer markets.

The BCW66G belongs to ON Semiconductor's general-purpose bipolar transistor product line, engineered for cost-sensitive, high-volume applications demanding reliable amplification and switching up to 500 mA in compact SOT-23 packages.

FAQ

What is the maximum continuous collector current rating for BCW66G?

The BCW66G has a maximum continuous collector current (I_C) rating of 1 A at T_C = 25 °C. However, practical operation at 500 mA is recommended for sustained use due to thermal limitations - its R_θJA of 357 °C/W and P_D of 350 mW require careful PCB thermal design to avoid exceeding 150 °C junction temperature. Always verify derated current against actual board layout and ambient conditions when using BCW66G.

Does BCW66G have a documented pinout compatible with standard SOT-23 footprints?

Yes, BCW66G uses the standard SOT-23 package with confirmed pinout: Pin 1 = Base, Pin 2 = Emitter, Pin 3 = Collector. This matches JEDEC MO-215 and is mechanically and electrically compatible with other SOT-23 NPN transistors like MMBT3904 and BC847 series. The top-mark "EG" is laser-etched per ON Semiconductor's marking standard for BCW66G.

What is the typical noise figure of BCW66G and at what conditions is it specified?

The BCW66G has a noise figure of 10 dB, measured at V_CE = 5 V, I_C = 0.2 mA, R_S = 1 kΩ, f = 1 kHz, and BW = 200 Hz. This value reflects its suitability for low-noise preamplifier stages in audio and sensor signal chains. Note that noise performance degrades at higher currents or frequencies - for BCW66G, optimal noise behavior occurs in the 0.1–1 mA I_C range.

Can BCW66G be used in switching applications, and what are its key timing parameters?

Yes, BCW66G is qualified for switching use with t_on = 100 ns and t_off = 400 ns under I_B1 = I_B2 = 15 mA, I_C = 150 mA, and R_L = 150 Ω. These values indicate moderate-speed performance suitable for PWM dimming, relay drivers, and digital logic interfacing below 1 MHz. For BCW66G, ensure base drive strength exceeds 15 mA to achieve specified switching times and avoid storage-time delays.

Is BCW66G RoHS compliant and halogen-free?

Yes, BCW66G is RoHS compliant and halogen-free per ON Semiconductor's product change notices and material declarations. As a Fairchild-integrated part now manufactured under ON Semiconductor's quality system, BCW66G meets J-STD-609B Class 1 for halogen content and EU Directive 2011/65/EU. Full compliance documentation, including test reports and substance declarations, is available upon request for BCW66G through Aetrix Electronics' technical support portal.

BCW66G Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

Package/Case:: TO-236-3, SC-59, SOT-23-3

Packaging:: Tape & Reel (TR)

Product Status:: Obsolete

Transistor Type:: NPN

Current - Collector (Ic) (Max):: 1 A

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

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

Current - Collector Cutoff (Max):: 20nA

DC Current Gain (hFE) (Min) @ Ic, Vce:: 160 @ 100mA, 1V

Power - Max:: 350 mW

Frequency - Transition:: 100MHz

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

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: SOT-23-3

BCW66G FAQ

1.How can I place an order for BCW66G through Aetrix?

Please submit a Request for Quotation (RFQ) for BCW66G 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 BCW66G reliable?

The price and inventory of BCW66G are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BCW66G is usually 5 days.

3.What payment methods are accepted for BCW66G?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BCW66G transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for BCW66G?

BCW66G orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your BCW66G 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 BCW66G?

For technical support, including BCW66G datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BCW66G requirements.

6.How does Aetrix verify that BCW66G is sourced from the original manufacturer or authorized distributors?

All BCW66G 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 BCW66G meets industry standards.

7.What is the process for return or replacement of BCW66G?

All BCW66G units undergo pre-shipment inspection (PSI). If there is an issue with BCW66G, 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 BCW66G part is unused and in its original packaging.

Return procedure for BCW66G:

1.Submit a request within 90 days.

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

Tech Hub

2026-09-09 Counterfeit Electronic Components: How to Detect, Authenticate, and Test Suspect Parts

Counterfeit components can hide behind convincing markings and passing basic function tests. This engineering reference covers source traceability, external inspection, X-ray, XRF, electrical testing, …

2026-09-08 Obsolete Electronic Components: How to Source and Evaluate Replacements

A practical engineering and sourcing framework covering lifecycle verification, lifetime-buy calculations, replacement qualification, supplier checks and counterfeit-risk controls.

2026-09-07 TTL vs CMOS Logic Levels: 74HC and 74HCT Compatibility Explained

TTL and CMOS logic families differ in thresholds, loading, output drive, power and timing. This engineering guide compares 74HC and 74HCT, calculates noise margins and checks 3.3 V/5 V compatibility.

2026-09-04 Logic Level Shifter: How to Connect 3.3V and 5V Logic Safely

A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.

2026-09-03 74HC595 vs TPIC6B595: Output Drive, Pinout, Current, and Load Selection

The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…

2026-09-02 74HC595 Pinout, Timing, Output Current, and Applications

The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…

2026-09-01 Latch vs Flip-Flop: Timing, Differences and Design Choices

A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…

2026-08-30 D Latch Circuit: Truth Table, Timing, ICs and Applications

A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …

2026-08-28 SR Latch Explained: NOR and NAND Circuits, Truth Tables, and Applications

An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…

2026-08-27 Latch Circuit: SR and D Latches, Truth Tables, Timing, and Applications

Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…