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

Diodes Incorporated BCW66HQTA

Name: BCW66HQTA
Brand: Diodes Incorporated
SKU: BCW66HQTA
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: BCW66HQTA

Manufacturer:: Diodes Incorporated

Category:: Single Bipolar Transistors

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

Datasheet:: BCW66HQTA.pdf

Description:: TRANS NPN 45V 0.8A SOT-23-3

Quantity:: RFQ Add To RFQ list

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Inventory:2,980

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Product details

Overview

BCW66HQTA from Diodes Incorporated is a 45V NPN medium-power bipolar junction transistor in SOT23 package, rated for 800mA continuous collector current and featuring V_CE(sat) < 300mV at 100mA/10mA drive. It delivers h_FE = 100–350 at I_C = 100mA/V_CE = 1V and f_T = 100MHz, supporting linear amplification and switching in DC-DC feedback paths and load drivers.

For engineers reviewing the BCW66HQTA datasheet, BCW66HQTA pinout, BCW66HQTA application, or BCW66HQTA equivalent, key selection criteria include V_CEO = 45V rating, SOT23 thermal resistance (R_θJA = 403°C/W on minimal PCB), low saturation voltage under 100mA load, and complementary pairing with BCW68H for push-pull stages.

Technical Context

This NPN transistor operates as a medium-current gain switch or linear amplifier with defined breakdown limits: V_CEO = 45V, V_CBO = 75V, and V_EBO = 7V. Its h_FE varies from 80 (at 100µA) to 630 (at 500mA), enabling stable biasing across wide current ranges.

Small-signal behavior includes f_T = 100MHz at I_C = 20mA/V_CE = 10V and C_obo = 8–12pF at V_CB = 10V, supporting high-frequency switching up to ~30MHz in practical layouts. Noise figure is 2–10dB at I_C = 0.2mA, suitable for low-noise preamp stages.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	45 V - Maximum safe collector-emitter voltage before avalanche conduction in common-emitter configuration.
I_C (cont.)	800 mA - Continuous DC collector current capability without thermal runaway on standard FR4 layout.
V_CE(sat)	< 300 mV @ I_C = 100mA, I_B = 10mA - Enables low-loss switching in 3.3V/5V logic-driven power stages.
h_FE	100–350 @ I_C = 100mA, V_CE = 1V - Provides predictable DC gain for emitter-follower buffers and current mirrors.
f_T	100 MHz @ I_C = 20mA, V_CE = 10V - Supports RF switching and broadband amplification up to mid-VHF range.
R_θJA	403 °C/W - Junction-to-ambient thermal resistance on minimal 1oz copper pad; dictates max power derating above 25°C ambient.
P_D	310 mW - Maximum steady-state power dissipation at T_A = 25°C with specified PCB copper area.

Pinout & Package

Package: SOT23 - Surface-mount plastic package with matte tin-plated leads, UL 94V-0 rated molding compound, 0.008g mass, and moisture sensitivity level 1 per J-STD-020.

Pin/Terminal	Circuit Role	Design Meaning
1 (Emitter)	Current sink terminal	Reference node for base drive; connects to ground or low-side return path in switching configurations.
2 (Base)	Control input	Receives current-limited drive signal; requires ≥10mA for full saturation at 100mA collector load.
3 (Collector)	Current source terminal	Connects to load or supply rail; handles up to 45V potential swing relative to emitter.

Key Features

Feature	Design Value
High V_CEO rating	45V withstand enables use in 24V industrial control rails and automotive 12V systems with transient margin.
Low V_CE(sat)	<300mV at 100mA reduces conduction loss by >60% vs. general-purpose transistors like BC847.
Complementary PNP pair	BCW68H shares identical SOT23 footprint and matching gain/breakdown specs for push-pull output stages.
Green RoHS compliance	Halogen- and antimony-free (<900ppm Br/Cl, <1000ppm Sb) meets automotive and medical regulatory requirements.

Applications

Motor Driver Stage

DC-DC Feedback Amplifier

Use Scenario: Driving small brushed DC motors (e.g., fans, actuators) in 5–24V embedded systems with PWM control.

IC Role / Device Role / Timing Role: NPN switch controlling motor current path between supply and ground; operated in saturation for minimal power loss.

Use Value: V_CE(sat) < 300mV ensures <150mW loss at 500mA, reducing thermal stress in compact enclosures.

Use Scenario: Amplifying error voltage in isolated flyback or buck converter feedback loops.

IC Role / Device Role / Timing Role: Linear amplifier stage translating optocoupler output into precise reference voltage for PWM controller.

Use Value: h_FE = 100–350 provides stable gain over temperature, minimizing regulation drift across -40°C to +125°C.

LED Constant-Current Sink

Signal-Level Shifter

Use Scenario: Sinking current for high-brightness LEDs in automotive interior lighting or industrial status indicators.

IC Role / Device Role / Timing Role: Current-regulated switch operating in active region with emitter resistor feedback.

Use Value: V_CEO = 45V supports 36V LED strings with headroom for line transients.

Use Scenario: Level-shifting 1.8V/3.3V logic signals to 5V/12V domains in mixed-voltage microcontroller interfaces.

IC Role / Device Role / Timing Role: Common-emitter inverter with fixed bias network, providing clean digital edge translation.

Use Value: f_T = 100MHz allows reliable operation up to 10MHz data rates with controlled rise/fall times.

Equivalent & Alternatives

The following parts are listed as comparable options for similar NPN medium-power transistor applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
BC847B	V_CEO = 45V, I_C = 100mA, h_FE = 200–450 - lower current rating and higher gain variation.	Not suitable for >200mA loads; limited thermal margin in sustained switching.	Select when gain stability at low current (1–10mA) is prioritized over power handling.
MMBT3904	V_CEO = 40V, I_C = 200mA, V_CE(sat) = 0.3V @ 50mA - narrower voltage margin and reduced current capacity.	Requires derating in 24V systems; unsuitable for motor loads >150mA.	Choose only for low-power signal switching where SOT23 footprint compatibility is critical.

Compared with BC847B and MMBT3904, BCW66HQTA offers 4× higher continuous current (800mA vs. ≤200mA), 10% higher V_CEO, and lower thermal resistance-making it uniquely suited for thermally constrained, medium-power analog and switching tasks.

Availability

BCW66HQTA is available at Aetrix Electronics and suitable for motor driver stages, DC-DC feedback amplifiers, LED constant-current sinks, and signal-level shifters requiring stable component supply and automotive-grade reliability.

Supply support for BCW66HQTA 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

Diodes Incorporated is a global manufacturer of discrete semiconductors and analog ICs, specializing in high-reliability components for industrial, automotive, and computing markets.

The BCW66H series belongs to Diodes' medium-power bipolar transistor product line, engineered for robust performance in space-constrained power switching and linear amplification applications across extended temperature ranges.

FAQ

What is the maximum allowable collector-emitter voltage for BCW66HQTA?

The absolute maximum V_CEO is 45V under open-base conditions at T_A = 25°C. Operation above this voltage risks avalanche breakdown and irreversible device failure. Derating is required above 25°C ambient per the datasheet's derating curve, with R_θJA = 403°C/W defining the thermal limit.

Is BCW66HQTA pin-compatible with BCW68HQTA?

No-BCW66HQTA is NPN while BCW68HQTA is its complementary PNP counterpart. Both share identical SOT23 pinout (E-B-C), but polarity reversal means direct substitution would invert circuit function. They are designed for paired use in push-pull or H-bridge topologies, not interchangeability.

Does BCW66HQTA meet automotive qualification standards?

The BCW66HQTA variant is explicitly designated as automotive-compliant per a separate datasheet (BCW66HQ). It meets AEC-Q101 stress test requirements, including temperature cycling, humidity bias, and ESD robustness, making it suitable for under-hood and infotainment applications where standard BCW66H is not qualified.

How does the thermal performance of BCW66HQTA compare between minimum and enhanced PCB layouts?

On a minimal 1oz FR4 pad, R_θJA = 403°C/W limits usable power to ~310mW at 25°C ambient. With a 15mm × 15mm copper area, R_θJA improves to 357°C/W, increasing dissipation to ~350mW. This 13% gain enables higher duty-cycle operation in compact designs without forced cooling.

BCW66HQTA Specifications

Product attributes: Attribute value

Manufacturer:: Diodes Incorporated

Series:: -

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

Packaging:: Tape & Reel (TR)

Product Status:: Active

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):: 20nA

DC Current Gain (hFE) (Min) @ Ic, Vce:: 250 @ 100mA, 1V

Power - Max:: 310 mW

Frequency - Transition:: 100MHz

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

Grade:: Automotive

Qualification:: AEC-Q101

Mounting Type:: Surface Mount

Supplier Device Package:: SOT-23-3

BCW66HQTA FAQ

1.How can I place an order for BCW66HQTA through Aetrix?

Please submit a Request for Quotation (RFQ) for BCW66HQTA 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 BCW66HQTA reliable?

The price and inventory of BCW66HQTA are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BCW66HQTA is usually 5 days.

3.What payment methods are accepted for BCW66HQTA?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BCW66HQTA transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for BCW66HQTA?

BCW66HQTA orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your BCW66HQTA 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 BCW66HQTA?

For technical support, including BCW66HQTA datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BCW66HQTA requirements.

6.How does Aetrix verify that BCW66HQTA is sourced from the original manufacturer or authorized distributors?

All BCW66HQTA 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 BCW66HQTA meets industry standards.

7.What is the process for return or replacement of BCW66HQTA?

All BCW66HQTA units undergo pre-shipment inspection (PSI). If there is an issue with BCW66HQTA, 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 BCW66HQTA part is unused and in its original packaging.

Return procedure for BCW66HQTA:

1.Submit a request within 90 days.

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

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