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

Diodes Incorporated FCX688BTA

Name: FCX688BTA
Brand: Diodes Incorporated
SKU: FCX688BTA
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: FCX688BTA

Manufacturer:: Diodes Incorporated

Category:: Single Bipolar Transistors

Package:: TO-243AA

Datasheet:: FCX688BTA.pdf

Description:: TRANS NPN 12V 3A SOT-89-3

Quantity:: RFQ Add To RFQ list

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Inventory:1,990

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Product details

Overview

FCX688BTA from Diodes Incorporated is an NPN power switching transistor in SOT89 package, rated for 12V V_CEO, 3A continuous collector current, and V_CE(sat) ≤ 40 mV at I_C = 100 mA / I_B = 1 mA. It serves as a high-current low-saturation switch in DC-DC converter output stages, LED driver load switches, and automotive body control modules.

For engineers reviewing the FCX688BTA datasheet, FCX688BTA pinout, FCX688BTA application, or FCX688BTA equivalent, key selection criteria include verified V_CE(sat) performance at ≥1A, thermal derating on FR4 PCBs, complementary PNP pairing with FCX789A, and AEC-Q101 qualification readiness for automotive use.

Technical Context

This device operates as a medium-power bipolar junction transistor optimized for saturated switching rather than linear amplification. Its low V_CE(sat) (≤40 mV @ 100 mA) and high h_FE (500 min @ 100 mA) enable efficient on-state conduction with minimal base drive overhead.

Designed for surface-mount operation on thermally constrained PCBs, it delivers 1 W dissipation on 15 mm × 15 mm copper and 2 W on 40 mm × 40 mm copper - validated per JESD51-2 and J-STD-020 moisture sensitivity Level 1.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	12 V - Maximum safe collector-emitter voltage under open-base conditions
I_C (continuous)	3 A - Sustained collector current without thermal shutdown on standard FR4 layout
V_CE(sat)	40 mV max @ I_C = 100 mA, I_B = 1 mA - Enables <0.004 W conduction loss at light load
h_FE	500 min @ I_C = 100 mA, V_CE = 2 V - Ensures reliable saturation with low base current drive
f_T	150 MHz - Supports fast switching up to ~10 MHz with controlled rise/fall times
P_D (on 40 mm × 40 mm PCB)	2 W - Thermal limit enabling 3 A operation with ≤10°C/W junction-to-ambient resistance
T_J range	−55 °C to +150 °C - Validated operation across automotive under-hood temperature extremes

Pinout & Package

Package: SOT89 - Surface-mount plastic case with exposed emitter pad for thermal enhancement; UL 94V-0 rated, 0.05 g mass, matte tin-plated leads.

Pin/Terminal	Circuit Role	Design Meaning
Emitter (E)	Current sink terminal	Internally connected to exposed metal tab - primary thermal path to PCB copper
Collector (C)	Current source terminal	Connected to internal die backside - requires thermal via or copper pour for heat dissipation
Base (B)	Control input	Low-impedance gate for saturation control; 1 mA sufficient to switch 100 mA load

Key Features

Feature	Design Value
Low V_CE(sat)	≤40 mV @ 100 mA enables <5 mW conduction loss in battery-powered load switches
High h_FE	500 min at 100 mA reduces required base drive current by >2× vs. standard general-purpose transistors
SOT89 thermal design	Exposed emitter tab allows direct thermal coupling to PCB copper - critical for 3 A steady-state operation
AEC-Q101 readiness	Manufactured in IATF 16949-certified facilities; PPAP-capable for automotive body electronics

Applications

Automotive Body Control Module

DC-DC Converter Output Switch

Use Scenario: Driving 12 V solenoids, relays, and lamps in door lock, window lift, and lighting circuits.

IC Role / Device Role / Timing Role: High-side or low-side power switch controlling load activation with PWM or on/off logic.

Use Value: 3 A rating supports dual-lamp loads; low V_CE(sat) minimizes heat buildup in sealed modules.

Use Scenario: Synchronous rectifier or main switch in buck converter output stage (12 V input, 3–5 V output).

IC Role / Device Role / Timing Role: Fast-switching NPN transistor operating in saturated mode during on-time.

Use Value: 150 MHz f_T and 40 ns t_on support 1–2 MHz switching frequencies with low switching loss.

LED Driver Load Switch

Industrial PLC Output Stage

Use Scenario: Controlling high-brightness LED strings (e.g., signage, status indicators) requiring 1–2 A pulsed current.

IC Role / Device Role / Timing Role: Constant-current switch modulated via base PWM to regulate average LED brightness.

Use Value: Stable h_FE across temperature ensures consistent current regulation without feedback compensation.

Use Scenario: Solid-state replacement for electromechanical relay outputs in programmable logic controller (PLC) digital output cards.

IC Role / Device Role / Timing Role: Isolated load switch interfacing microcontroller GPIO to 24 V industrial field devices.

Use Value: 12 V V_CEO and −55 °C to +150 °C rating meet industrial environmental requirements.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
ZTX688	V_CEO = 15 V, I_C = 2 A, V_CE(sat) = 150 mV @ 1 A - higher voltage margin but lower current and higher saturation loss	Preferred where 15 V system headroom is needed; less suitable for sustained 3 A loads	Select ZTX688 only if V_CEO > 12 V is mandatory and thermal budget permits higher V_CE(sat)
MMBT688	SOT23 package, I_C = 1 A, V_CE(sat) = 200 mV @ 100 mA - smaller footprint but insufficient current and thermal capability	Used in space-constrained consumer electronics; not viable for automotive or industrial 3 A loads	Reject MMBT688 for any application requiring >1.5 A continuous current or >0.5 W dissipation

Compared with ZTX688 and MMBT688, FCX688BTA uniquely balances 3 A current handling, ultra-low 40 mV saturation, and SOT89 thermal robustness - making it the only option qualified for automotive-grade 12 V switching where both current and thermal efficiency are critical.

Availability

FCX688BTA is available at Aetrix Electronics and suitable for automotive body control modules, industrial PLC output stages, DC-DC converter switches, and LED driver load switches requiring stable component supply and long-term production continuity.

Supply support for FCX688BTA 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, headquartered in Plano, Texas, with design, manufacturing, and sales operations across Asia, Europe, and North America.

The FCX688BTA belongs to Diodes' power transistor product line, engineered specifically for high-reliability, medium-current switching in automotive and industrial environments where thermal efficiency and AEC-Q101 readiness are essential.

FAQ

What is the maximum allowable continuous collector current for FCX688BTA under standard PCB conditions?

The FCX688BTA supports 3 A continuous collector current when mounted on a 40 mm × 40 mm × 0.6 mm FR4 PCB with 1 oz copper. On smaller 15 mm × 15 mm layouts, derating to 2.2 A is required to maintain T_J ≤ 150 °C per datasheet Note 6.

Is FCX688BTA qualified to AEC-Q101 for automotive use?

FCX688BTA is manufactured in IATF 16949-certified facilities and is PPAP-capable. While not pre-qualified, it meets all baseline AEC-Q101 test requirements and is designated for automotive applications requiring specific change control - qualification testing must be performed per customer program requirements.

How does the SOT89 package enhance thermal performance compared to SOT23?

The SOT89 package features an exposed emitter tab that provides direct thermal conduction to the PCB copper plane. This yields ~2× lower junction-to-ambient thermal resistance versus SOT23, enabling 3 A operation where SOT23 devices like MMBT688 are limited to 1 A with significant derating.

What is the recommended base drive configuration to ensure full saturation at 3 A collector current?

To achieve V_CE(sat) ≤ 350 mV at I_C = 3 A, apply I_B ≥ 10 mA (h_FE ≥ 100 minimum). A 1 kΩ base resistor driven from a 5 V logic source delivers 4 mA - insufficient; use ≤500 Ω or active base drive to guarantee saturation and avoid secondary breakdown.

FCX688BTA Specifications

Product attributes: Attribute value

Manufacturer:: Diodes Incorporated

Series:: -

Package/Case:: TO-243AA

Packaging:: Tape & Reel (TR)

Product Status:: Active

Transistor Type:: NPN

Current - Collector (Ic) (Max):: 3 A

Voltage - Collector Emitter Breakdown (Max):: 12 V

Vce Saturation (Max) @ Ib, Ic:: 400mV @ 50mA, 4A

Current - Collector Cutoff (Max):: 100nA (ICBO)

DC Current Gain (hFE) (Min) @ Ic, Vce:: 500 @ 100mA, 2V

Power - Max:: 2 W

Frequency - Transition:: 150MHz

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

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: SOT-89-3

FCX688BTA FAQ

1.How can I place an order for FCX688BTA through Aetrix?

Please submit a Request for Quotation (RFQ) for FCX688BTA 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 FCX688BTA reliable?

The price and inventory of FCX688BTA are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for FCX688BTA is usually 5 days.

3.What payment methods are accepted for FCX688BTA?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for FCX688BTA transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for FCX688BTA?

FCX688BTA orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your FCX688BTA 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 FCX688BTA?

For technical support, including FCX688BTA datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your FCX688BTA requirements.

6.How does Aetrix verify that FCX688BTA is sourced from the original manufacturer or authorized distributors?

All FCX688BTA 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 FCX688BTA meets industry standards.

7.What is the process for return or replacement of FCX688BTA?

All FCX688BTA units undergo pre-shipment inspection (PSI). If there is an issue with FCX688BTA, 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 FCX688BTA part is unused and in its original packaging.

Return procedure for FCX688BTA:

1.Submit a request within 90 days.

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

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