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

Diodes Incorporated BCX41QTA

Name: BCX41QTA
Brand: Diodes Incorporated
SKU: BCX41QTA
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: BCX41QTA

Manufacturer:: Diodes Incorporated

Category:: Single Bipolar Transistors

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

Datasheet:: BCX41QTA.pdf

Description:: TRANS NPN 125V 0.8A SOT-23-3

Quantity:: RFQ Add To RFQ list

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Inventory:2,825

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Product details

Overview

BCX41QTA from Diodes Incorporated is a 125V NPN medium-power bipolar junction transistor in SOT23 package, qualified to AEC-Q101 for automotive use, with 800mA continuous collector current, 310mW power dissipation at 25°C, and 4kV HBM ESD rating - deployed in automotive lighting control and body electronics switching circuits.

For engineers reviewing the BCX41QTA datasheet, BCX41QTA pinout, BCX41QTA application, or BCX41QTA equivalent, key selection criteria include V_CEO ≥ 125V, I_C ≥ 800mA, AEC-Q101 qualification, SOT23 thermal performance (R_θJA = 403°C/W), and h_FE range of 25–400 across operating conditions.

Technical Context

This NPN BJT operates as a medium-power switch in linear or saturated mode, supporting DC and pulsed loads up to 1A peak. Its 125V V_CEO and V_CB0 ratings enable use in 24V/48V automotive subsystems with transient margin, while its 100MHz f_T supports moderate-speed switching above 10kHz.

The device features low V_CE(SAT) ≤ 0.9V at I_C = 300mA/I_B = 30mA and V_BE(SAT) ≤ 1.4V under same conditions, enabling efficient drive in discrete driver stages. Its -55°C to +150°C operating range and AEC-Q101 qualification confirm suitability for under-hood environments.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	125 V - Withstands 125V collector-emitter voltage before breakdown, enabling robust operation in 24V automotive systems with load-dump transients.
I_C (continuous)	800 mA - Supports sustained switching of medium-current loads such as LED arrays, solenoids, and relay coils.
P_D @ 25°C	310 mW - Power limit on standard FR-4 PCB with minimal copper; derates linearly above 25°C ambient per published curve.
h_FE	25–400 - Current gain varies with I_C: 25 at 100µA, 63 typical at 100mA, 40 min at 200mA - critical for base drive sizing.
f_T	100 MHz - Transition frequency measured at I_C = 10mA/V_CE = 5V; enables reliable switching up to ~10MHz square-wave edge rates.
ESD HBM	4,000 V - JEDEC Class 3A rating ensures handling robustness during assembly without special ESD controls beyond standard practices.

Pinout & Package

SOT23 plastic surface-mount package (3-pin, 2.4mm × 1.3mm × 1.0mm), UL 94V-0 rated, matte tin-plated leads, moisture sensitivity level 1.

Pin/Terminal	Circuit Role	Design Meaning
1 (Emitter)	E	Current return path; connected to ground or low-side reference; requires low-inductance layout for switching stability.
2 (Base)	B	Control input; driven by MCU GPIO or logic buffer; requires series resistor to limit I_B ≤ 100mA absolute max.
3 (Collector)	C	High-side load connection; carries full switched current; routed over thermal pad or wide trace for heat dissipation.

Key Features

Feature	Design Value
AEC-Q101 qualified	Validated for automotive temperature cycling, mechanical shock, and humidity testing - required for Tier-1 production release.
Lead-free & halogen-free	Meets RoHS 2 and JESD22-A112; <900ppm Br/Cl, <1000ppm Sb - satisfies global environmental compliance mandates.
V_CEO = 125V	Exceeds ISO 7637-2 Pulse 1/2/5a requirements for 24V systems - eliminates need for external clamping in many applications.
R_θJA = 403°C/W	Thermal resistance on minimal FR-4 pad; enables 800mA operation up to ~85°C ambient with proper board layout.

Applications

Automotive LED Headlamp Switching

Body Control Module Load Driver

Use Scenario: Driving high-brightness LED strings in adaptive front-lighting systems with PWM dimming.

IC Role / Device Role / Timing Role: NPN switch controlling LED cathode path; operated in saturation for low conduction loss.

Use Value: V_CE(SAT) ≤ 0.9V at 300mA reduces power loss to <270mW, minimizing thermal stress in compact headlamp housings.

Use Scenario: Switching 12V solenoid valves and window motor relays in centralized body controllers.

IC Role / Device Role / Timing Role: Discrete high-side or low-side driver replacing integrated load switches where cost and failure isolation are critical.

Use Value: 125V V_CEO withstands load-dump transients up to ±100V, eliminating need for external TVS in many BCM designs.

Industrial Sensor Interface Protection

Power Supply Enable Circuit

Use Scenario: Isolating and protecting analog sensor outputs from field-induced surges in factory automation nodes.

IC Role / Device Role / Timing Role: Transistor used in active clamping or current-limiting stage upstream of ADC inputs.

Use Value: 4kV HBM ESD rating and 150°C max junction temperature allow direct placement near I/O connectors without additional protection ICs.

Use Scenario: Enabling/disabling auxiliary 5V or 3.3V rails in multi-rail industrial power supplies.

IC Role / Device Role / Timing Role: Low-leakage, high-V_CEO switch controlling PMOS gate drive or LDO EN pin.

Use Value: I_CES ≤ 10nA at 100V ensures <1µA standby current - critical for low-power sleep modes in energy-sensitive systems.

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
ZTX653	V_CEO = 100V, I_C = 1A, SOT89 package, R_θJA = 120°C/W	Higher current but lower voltage rating; larger thermal footprint	Select when higher I_C and better thermal performance are needed, and 100V rating suffices.
BC817-40	V_CEO = 45V, I_C = 500mA, SOT23, h_FE = 250–630	Lower voltage/current; optimized for general-purpose signal switching, not automotive transients	Choose only for non-automotive, low-voltage (<24V) logic-level interface applications.

Compared with ZTX653 and BC817-40, BCX41QTA uniquely balances 125V ruggedness, AEC-Q101 qualification, and SOT23 form factor - making it the only option among the three suitable for space-constrained, high-reliability automotive switching where both voltage margin and qualification matter.

Availability

BCX41QTA is available at Aetrix Electronics and suitable for automotive lighting control, body electronics modules, industrial sensor interfaces, and power rail enable circuits requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for BCX41QTA 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 automotive, industrial, and computing markets.

The BCX41QTA belongs to Diodes' AEC-Q101-qualified bipolar transistor product line, engineered specifically for automotive power switching applications demanding high voltage tolerance, thermal resilience, and long-term reliability under harsh environmental stress.

FAQ

Is BCX41QTA suitable for 48V mild-hybrid vehicle systems?

Yes - its 125V V_CEO and V_CB0 ratings provide 2.6× margin over nominal 48V bus, and its -55°C to +150°C operating range meets ISO 16750-4 requirements for powertrain-adjacent locations. Derating curves confirm usable I_C at elevated ambient temperatures.

What is the maximum safe base current for continuous operation?

The absolute maximum rated base current is 100mA, but for reliable continuous operation, IB should be limited to ≤30mA (per V_BE(SAT) test condition). Exceeding this risks thermal runaway due to β degradation at high junction temperatures, especially above 100°C ambient.

Does BCX41QTA require a heatsink in SOT23 footprint?

No external heatsink is required. At 800mA I_C and 0.9V V_CE(SAT), power dissipation is ≤720mW - exceeding the 310mW rating. Therefore, operation must be thermally derated: max I_C is ~450mA at 25°C ambient on minimal copper, dropping to ~200mA at 85°C ambient per published derating curve.

Can BCX41QTA replace BCX41 in existing designs?

Yes - BCX41QTA is the AEC-Q101-qualified, green-compliant version of BCX41 with identical pinout, electrical specs, and SOT23 package. Key improvements include enhanced ESD robustness (4kV HBM vs. unspecified), tighter process control, and automotive-grade traceability - no layout or schematic changes needed for drop-in replacement.

BCX41QTA 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):: 125 V

Vce Saturation (Max) @ Ib, Ic:: 900mV @ 30mA, 300mA

Current - Collector Cutoff (Max):: 75µA

DC Current Gain (hFE) (Min) @ Ic, Vce:: 63 @ 100mA, 1V

Power - Max:: 330 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

BCX41QTA FAQ

1.How can I place an order for BCX41QTA through Aetrix?

Please submit a Request for Quotation (RFQ) for BCX41QTA 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 BCX41QTA reliable?

The price and inventory of BCX41QTA are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BCX41QTA is usually 5 days.

3.What payment methods are accepted for BCX41QTA?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BCX41QTA transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for BCX41QTA?

BCX41QTA orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your BCX41QTA 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 BCX41QTA?

For technical support, including BCX41QTA datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BCX41QTA requirements.

6.How does Aetrix verify that BCX41QTA is sourced from the original manufacturer or authorized distributors?

All BCX41QTA 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 BCX41QTA meets industry standards.

7.What is the process for return or replacement of BCX41QTA?

All BCX41QTA units undergo pre-shipment inspection (PSI). If there is an issue with BCX41QTA, 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 BCX41QTA part is unused and in its original packaging.

Return procedure for BCX41QTA:

1.Submit a request within 90 days.

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

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