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

Diodes Incorporated BCW66HTA

Name: BCW66HTA
Brand: Diodes Incorporated
SKU: BCW66HTA
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: BCW66HTA

Manufacturer:: Diodes Incorporated

Category:: Single Bipolar Transistors

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

Datasheet:: BCW66HTA.pdf

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

Quantity:: RFQ Add To RFQ list

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Inventory:19,862

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Product details

Overview

BCW66HTA 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-used in low-voltage switching and linear amplification stages of industrial power supplies, LED drivers, and motor control interfaces.

For engineers reviewing the BCW66HTA datasheet, BCW66HTA pinout, BCW66HTA application, or BCW66HTA equivalent, key selection criteria include V_CEO = 45V, h_FE = 100–630 (IC = 100µA to 500mA), f_T = 100MHz, thermal resistance R_θJA = 403°C/W (min pad), and SOT23-compatible footprint with EH marking.

Technical Context

This NPN BJT operates in active, saturation, and cutoff regions with verified DC gain spanning 100–630 across collector currents from 100µA to 500mA. Its 100MHz transition frequency supports high-speed switching up to ~10MHz square-wave operation under proper drive conditions.

Thermal performance is defined for two PCB mounting conditions: 403°C/W on minimal FR4 pad and 357°C/W on 15mm × 15mm copper area. Saturation voltage remains ≤300mV at IC = 100mA/IB = 10mA, enabling efficient low-side switch operation in 3.3V–24V systems.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	45 V - Maximum safe collector-emitter voltage before breakdown in common-emitter configuration.
I_C (cont.)	800 mA - Continuous collector current rating defining maximum steady-state load-handling capability.
V_CE(sat)	< 300 mV @ IC = 100mA, IB = 10mA - Ensures low conduction loss and minimal self-heating in saturated-switch applications.
h_FE	100–630 - DC current gain range across operating conditions, supporting stable biasing from signal-level to medium-power stages.
f_T	100 MHz - Transition frequency indicating usable bandwidth for small-signal amplification or fast switching.
R_θJA	403 °C/W - Junction-to-ambient thermal resistance on standard single-sided FR4 layout, guiding heatsinking requirements.

Pinout & Package

Package: SOT23 - Surface-mount plastic package with 3-pin leadframe, 0.008g mass, UL 94V-0 rated molding compound, and matte tin-plated leads compliant with MIL-STD-202.

Pin/Terminal	Circuit Role	Design Meaning
1 (Emitter)	E	Current sink node; connects to ground or low-side return path in switching configurations.
2 (Base)	B	Control input requiring ~10mA drive for full saturation at 100mA collector load.
3 (Collector)	C	Current source node; connects to load supply rail in low-side switch topology.

Key Features

Feature	Design Value
High BV_CEO	45 V enables use in 24V industrial bus and 36V automotive auxiliary circuits without derating.
Low V_CE(sat)	<300 mV at 100mA reduces power dissipation to <30mW in saturated switch mode.
Wide h_FE range	100–630 accommodates production spread while maintaining reliable turn-on across temperature (-55°C to +150°C).
Automotive-grade variant	BCW66HQ exists with AEC-Q101 qualification, supporting direct upgrade paths for automotive designs.

Applications

Industrial Power Supply Control

LED Constant-Current Driver

Use Scenario: Regulating feedback loop transistors and auxiliary bias rails in offline AC/DC converters and DC/DC modules.

IC Role / Device Role / Timing Role: NPN switch amplifying optocoupler output to drive PWM controller enable/disable or overcurrent latch signals.

Use Value: 45V V_CEO withstands reflected flyback spikes; 800mA I_C supports direct drive of small-signal MOSFET gates or logic inputs.

Use Scenario: Linear current regulation in low-cost LED lighting modules with analog dimming.

IC Role / Device Role / Timing Role: Emitter-follower configured as adjustable current sink controlling LED string current via base voltage reference.

Use Value: Low V_CE(sat) minimizes dropout voltage, allowing operation down to 2.5V supply while delivering 500mA LED current.

Brushed DC Motor Interface

Signal-Level Amplifier Stage

Use Scenario: Driving small brushed motors (e.g., fans, actuators) in HVAC controls and appliance subsystems.

IC Role / Device Role / Timing Role: Low-side switch controlled by microcontroller GPIO, handling bidirectional PWM at ≤20kHz.

Use Value: 100MHz f_T ensures clean edge fidelity; 403°C/W R_θJA allows 310mW dissipation without heatsink at ambient ≤60°C.

Use Scenario: Pre-amplification of sensor outputs (e.g., thermistor, hall-effect) prior to ADC sampling.

IC Role / Device Role / Timing Role: Common-emitter amplifier with emitter degeneration resistor for stable gain and linearity.

Use Value: h_FE ≥100 at 100µA supports high-input-impedance bias networks; noise figure ≤10dB maintains SNR in µV-range signals.

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
BC817-40	V_CEO = 45V, I_C = 500mA, h_FE = 250–630, R_θJA = 450°C/W	Lower current rating limits use in >500mA loads; higher thermal resistance requires tighter layout control.	Select when lower cost and tighter h_FE tolerance are prioritized over peak current headroom.
MMBT3904	V_CEO = 40V, I_C = 200mA, h_FE = 100–300, f_T = 300MHz	Insufficient V_CEO and I_C for 24V/800mA switching; better suited for signal amplification only.	Choose only for low-power signal gain where 40V rating and 200mA limit are acceptable.

Compared with BC817-40 and MMBT3904, BCW66HTA delivers higher continuous current (800mA vs. 500mA/200mA) and lower saturation voltage at rated load-making it preferable for robust medium-power switching where thermal margin and conduction loss are critical.

Availability

BCW66HTA is available at Aetrix Electronics and suitable for industrial power supply control, LED constant-current drivers, brushed DC motor interfaces, and signal-level amplifier stages requiring stable component supply and RoHS-compliant sourcing.

Supply support for BCW66HTA 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, computing, consumer, and automotive markets.

The BCW66H series belongs to Diodes' general-purpose bipolar transistor product line, designed specifically for cost-sensitive, medium-power switching and amplification applications requiring wide h_FE range and automotive-qualified variants.

FAQ

What is the maximum allowable junction temperature for BCW66HTA?

The BCW66HTA has an operating junction temperature range of –55°C to +150°C. This allows reliable operation in harsh environments such as industrial enclosures and under-hood automotive locations, provided thermal design respects the specified R_θJA and power dissipation limits.

Is BCW66HTA pin-compatible with BCW66G or BCW66F?

Yes-BCW66HTA, BCW66G, and BCW66F share identical SOT23 package and pinout (E-B-C). However, they differ in h_FE bins: BCW66HTA is binned 180–250, BCW66G is 100–160, and BCW66F is 250–400. Electrical substitution requires verifying gain requirements per circuit.

Does BCW66HTA support pulsed operation beyond its DC ratings?

Yes-peak pulse current I_CM is rated at 1000mA with duty cycle ≤2% and pulse width ≤300µs. This supports short-duration surge handling in motor start-up or fault-limited protection circuits, provided average power stays within 310mW limits.

Can BCW66HTA be used in place of a MOSFET for low-side switching?

It can serve as a low-side switch but lacks MOSFET advantages like zero gate drive current and near-zero R_DS(on). With V_CE(sat) <300mV at 100mA, it's viable for moderate-current, cost-sensitive applications where BJT simplicity and proven reliability outweigh efficiency demands.

BCW66HTA 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:: 330 mW

Frequency - Transition:: 100MHz

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

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: SOT-23-3

BCW66HTA FAQ

1.How can I place an order for BCW66HTA through Aetrix?

Please submit a Request for Quotation (RFQ) for BCW66HTA 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 BCW66HTA reliable?

The price and inventory of BCW66HTA are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BCW66HTA is usually 5 days.

3.What payment methods are accepted for BCW66HTA?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BCW66HTA transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for BCW66HTA?

BCW66HTA orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your BCW66HTA 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 BCW66HTA?

For technical support, including BCW66HTA datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BCW66HTA requirements.

6.How does Aetrix verify that BCW66HTA is sourced from the original manufacturer or authorized distributors?

All BCW66HTA 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 BCW66HTA meets industry standards.

7.What is the process for return or replacement of BCW66HTA?

All BCW66HTA units undergo pre-shipment inspection (PSI). If there is an issue with BCW66HTA, 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 BCW66HTA part is unused and in its original packaging.

Return procedure for BCW66HTA:

1.Submit a request within 90 days.

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

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