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

Diodes Incorporated FZT688BTC

Name: FZT688BTC
Brand: Diodes Incorporated
SKU: FZT688BTC
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

Compare

Part No.:: FZT688BTC

Manufacturer:: Diodes Incorporated

Category:: Single Bipolar Transistors

Package:: TO-261-4, TO-261AA

Datasheet:: FZT688BTC.pdf

Description:: TRANS NPN 12V 4A SOT-223-3

Quantity:: RFQ Add To RFQ list

Payment:

Shipping:

Inventory:2,491

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

Product details

Overview

FZT688BTC from Diodes Incorporated is an NPN silicon planar medium-power high-gain bipolar junction transistor in SOT-223 package, rated for 4 A continuous collector current, 12 V V_CEO, and 2 W power dissipation at 25°C ambient. It delivers h_FE = 400 at I_C = 3 A and V_CE = 2 V, with V_CE(sat) as low as 40 mV at I_C = 0.1 A / I_B = 1 mA - used in flash gun converters and battery-powered DC-DC boost stages.

For engineers reviewing the FZT688BTC datasheet, FZT688BTC pinout, FZT688BTC application, or FZT688BTC equivalent, key selection criteria include saturation voltage under high-current switching, gain stability across temperature (−55°C to +150°C), safe operating area (SOA) compliance at pulsed loads, and SOT-223 thermal performance in compact portable power circuits.

Technical Context

This BJT operates as a medium-power switch with fixed-base drive topology, optimized for low-duty-cycle, high-peak-current applications such as capacitor-charging flash circuits. Its f_T = 150 MHz and C_ibo = 200 pF support fast turn-on (t_on = 40 ns) while maintaining robust SOA up to 100 µs pulses at 10 V.

The device uses planar epitaxial construction with emitter ballasting for current sharing and thermal stability. Saturation behavior is characterized under pulsed conditions (300 µs width, ≤2% duty cycle), and V_BE(sat) = 1.1 V at I_C = 3 A / I_B = 20 mA confirms low base drive requirement for efficient switching.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	12 V - Maximum allowable collector-emitter voltage before breakdown; defines safe DC/peak voltage headroom in boost converter output stage
I_C (cont.)	4 A - Continuous collector current rating; sets maximum steady-state load current without derating at T_amb = 25°C
V_CE(sat)	40–400 mV - Measured at I_C = 0.1–4 A; directly determines conduction loss and thermal rise in switching node
h_FE	400 @ I_C = 3 A - High DC current gain enables low base drive current (I_B = 7.5 mA typical), reducing driver stage power
f_T	150 MHz - Transition frequency at I_C = 50 mA / V_CE = 5 V; supports sub-100 ns switching in pulsed power control
P_tot	2 W @ T_amb = 25°C - Total package power dissipation limit; requires heatsinking or airflow above ~1.2 W in enclosed designs
t_on/t_off	40 ns / 500 ns - Switching times at I_C = 500 mA; defines minimum pulse width and max repetition rate in flash charging

Pinout & Package

SOT-223 package with exposed emitter pad for thermal enhancement; standard 4-pin configuration (3 active + 1 thermal tab). Pin 1 = Emitter, Pin 2 = Base, Pin 3 = Collector, Pin 4 = Collector (tab-connected).

Pin/Terminal	Circuit Role	Design Meaning
Pin 1 (E)	Emitter	Main current return path; electrically and thermally connected to PCB copper pour for low-impedance grounding and heat sinking
Pin 2 (B)	Base	Control input for bipolar conduction; requires current-limited drive (e.g., 5–20 mA) to achieve specified h_FE and V_CE(sat)
Pin 3 (C)	Collector	High-side switched output node; tied internally to metal tab (Pin 4) for improved thermal transfer to heatsink
Pin 4 (Tab)	Collector (thermal)	Exposed copper pad soldered to PCB ground plane; contributes >60% of total thermal resistance reduction vs. non-tab packages

Key Features

Feature	Design Value
Low V_CE(sat)	40 mV at I_C = 0.1 A reduces conduction loss by >70% vs. standard medium-power BJTs in flash charging paths
High h_FE	400 at I_C = 3 A allows use of low-current microcontroller GPIO or logic buffer for direct base drive
Wide SOA	Rated for 10 A peak pulse (ICM) with defined 100 µs–1 s SOA curves - supports capacitor dump and surge load handling
Extended temperature range	−55°C to +150°C junction operation enables deployment in automotive interior lighting and industrial battery tools
SOT-223 thermal pad	Exposed collector tab lowers R_θJA to ~62°C/W (typical on 1-in² 2-oz Cu), critical for sustained 2–3 A pulsed loads

Applications

Flash Gun Converters

Battery-Powered DC-DC Boost Stages

Use Scenario: Rapid capacitor charging for xenon flash tubes in DSLR accessories and portable camera modules.

IC Role / Device Role / Timing Role: Main switching transistor in flyback or Royer oscillator topology; gated at 1–5 Hz with 300 µs pulses.

Use Value: Low V_CE(sat) minimizes energy loss during charge phase; high h_FE enables simple resistor-based base drive from low-power MCU.

Use Scenario: Step-up converter in handheld medical devices (e.g., pulse oximeters) powered by single-cell Li-ion (3.0–4.2 V).

IC Role / Device Role / Timing Role: Primary switch in discrete boost controller; operated in discontinuous conduction mode at ~100 kHz.

Use Value: 150 MHz f_T ensures clean switching edge; SOT-223 thermal pad maintains <85°C junction temp at 2.5 A peak.

Portable Power Tools

LED Flash Drivers

Use Scenario: Motor commutation assist and battery protection circuitry in cordless drills and screwdrivers.

IC Role / Device Role / Timing Role: High-side current limiter and reverse-polarity protection switch; triggered by overcurrent sense signal.

Use Value: 12 V V_CEO accommodates 12 V nominal battery packs with ripple; SOA supports 10 A motor stall surges.

Use Scenario: Strobe control in emergency beacons and bicycle safety lights using high-brightness white LEDs.

IC Role / Device Role / Timing Role: Constant-current switch in LED string driver; modulated at 1–20 Hz for visibility enhancement.

Use Value: 4 A I_C rating supports multi-LED arrays; low V_CE(sat) preserves battery runtime during 100 ms strobes.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
ZXTN25012E6TA	Higher V_CEO = 20 V, lower h_FE = 250 @ 3 A, SOT-23 package (no thermal tab)	Limited to <1.5 A continuous due to smaller package; unsuitable for >500 mW sustained dissipation	Choose only for space-constrained low-power boost stages where 12 V headroom is insufficient
MJD127G	Same SOT-223 package, but PNP complement; V_CEO = −100 V, I_C = −2 A, h_FE = 5000 @ −100 mA	Designed for high-voltage linear regulation or complementary push-pull output stages, not flash switching	Select only when building dual-rail or high-side PNP switch topologies requiring matched thermal footprint

Compared with ZXTN25012E6TA and MJD127G, FZT688BTC uniquely balances 4 A current capability, 40 mV saturation, and SOT-223 thermal performance - making it optimal for battery-fed pulsed power where efficiency, size, and thermal margin are co-constrained.

Availability

FZT688BTC is available at Aetrix Electronics and suitable for flash gun converters, battery-powered DC-DC boost stages, and portable power tool motor control requiring stable component supply and consistent parametric performance across production lots.

Supply support for FZT688BTC 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 centers across Asia and manufacturing in China, Taiwan, and the U.S.

FZT688BTC belongs to the FZT series of high-gain medium-power transistors engineered specifically for portable and pulsed-power applications where low saturation voltage and robust SOA are critical - not general-purpose switching.

FAQ

What is the maximum safe pulsed collector current for FZT688BTC?

The absolute maximum pulsed collector current (I_CM) is 10 A, specified under pulsed conditions (pulse width = 300 µs, duty cycle ≤2%). This rating is validated by SOA curves showing safe operation up to 100 µs at 10 V and 10 A. Exceeding these limits risks second breakdown or bond-wire fusing.

Can FZT688BTC replace a MOSFET in low-voltage switching applications?

No - FZT688BTC is a bipolar transistor requiring continuous base current drive, unlike voltage-controlled MOSFETs. While its 40 mV V_CE(sat) rivals some logic-level MOSFETs, it lacks gate capacitance benefits and cannot operate efficiently below ~0.5 V V_CE. Use only where BJT drive architecture is already established.

Is the SOT-223 thermal tab electrically isolated?

No - the exposed collector tab (Pin 4) is electrically connected to the collector terminal (Pin 3). When mounted on a PCB, this requires isolation from ground planes unless the collector node is referenced to system ground. Thermal interface material must be electrically insulating if mounting to a grounded heatsink.

Does FZT688BTC have SPICE model support?

Yes - Diodes Incorporated provides verified SPICE parameter data upon request for FZT688BTC, including Gummel-Poon model parameters extracted from measured DC and transient characteristics. The model supports accurate simulation of V_CE(sat), h_FE, and switching behavior under pulsed conditions.

FZT688BTC Specifications

Product attributes: Attribute value

Manufacturer:: Diodes Incorporated

Series:: -

Package/Case:: TO-261-4, TO-261AA

Packaging:: Tape & Reel (TR)

Product Status:: Obsolete

Transistor Type:: NPN

Current - Collector (Ic) (Max):: 4 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:: 400 @ 3A, 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-223-3

FZT688BTC FAQ

1.How can I place an order for FZT688BTC through Aetrix?

Please submit a Request for Quotation (RFQ) for FZT688BTC 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 FZT688BTC reliable?

The price and inventory of FZT688BTC are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for FZT688BTC is usually 5 days.

3.What payment methods are accepted for FZT688BTC?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for FZT688BTC transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for FZT688BTC?

FZT688BTC orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your FZT688BTC 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 FZT688BTC?

For technical support, including FZT688BTC datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your FZT688BTC requirements.

6.How does Aetrix verify that FZT688BTC is sourced from the original manufacturer or authorized distributors?

All FZT688BTC 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 FZT688BTC meets industry standards.

7.What is the process for return or replacement of FZT688BTC?

All FZT688BTC units undergo pre-shipment inspection (PSI). If there is an issue with FZT688BTC, 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 FZT688BTC part is unused and in its original packaging.

Return procedure for FZT688BTC:

1.Submit a request within 90 days.

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

Tech Hub

2026-08-21 What Is an LED Driver? Types, Circuits, Dimming, and Selection

An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…

2026-08-18 Operational Amplifier (Op Amp): Basics, Configurations, Feedback and Applications

Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…

2026-08-14 Jumper Cables: How to Use, Connect and Choose Them Safely

Jumper cables guide covering safe connection order, red and black clamp placement, final ground connection, cable gauge, length, clamp quality, copper vs CCA cables, jump starter comparison and battery…

2026-08-11 LDO Regulator: Dropout Voltage, Noise, PSRR and Power Dissipation

LDO regulator guide covering low dropout voltage, power dissipation, thermal design, PSRR, output noise, capacitor stability, adjustable LDO circuits, LDO vs buck converter and datasheet selection chec…

2026-08-06 Conditional Access Module: CAM, CI/CI+ and DVB Security

Conditional Access Module guide covering CAM meaning, CI/CI+ interface, smart card authorization, DVB security workflow, TV and set-top box compatibility, internal electronics, ESD protection, connecto…

2026-08-03 Electronic Component Obsolescence: EOL Risks, Replacement Options and Last-Time Buy Strategy

Guide to electronic component obsolescence covering EOL risk, PCN/PDN notices, last-time buy planning, replacement options, form-fit-function validation, counterfeit risk and BOM lifecycle management.

2026-07-29 18650 Battery: Voltage, Capacity, Charging and Pack Design

18650 battery guide covering lithium-ion cell basics, 3.6V/3.7V voltage, 4.2V charging, mAh and Wh capacity, protected cells, chargers, BMS, series-parallel packs, holders, welding and sourcing checks.…

2026-07-27 Hall Effect Sensor: Working Principle, Types, Circuits and Applications

Hall effect sensor guide covering working principle, linear and digital sensors, Arduino circuits, current sensing, speed detection, automotive applications, A3144 examples, signal filtering and datash…

2026-07-20 Product Change Notification (PCN) in Electronic Components: Meaning and Supply Chain Response

Product Change Notification guide for electronic components, covering PCN meaning, PCN vs PDN/EOL, common change types, risk levels, form-fit-function review, engineering validation, BOM control, LTB/L…

2026-07-19 Blend Door Actuator: Symptoms, Location, Reset and Replacement Guide

A practical guide to blend door actuators, covering HVAC function, symptoms, location, AC and heater issues, reset and calibration, replacement cost, electrical diagnosis, compatibility checks, and rep…