Diodes Incorporated FZT688BTA

Overview

FZT688BTA from Diodes Incorporated is an NPN silicon planar medium-power high-gain transistor in SOT-223 package, rated for 4 A continuous collector current, 12 V V_CEO, and 2 W power dissipation at T_amb=25°C; it delivers V_CE(sat) = 0.06 V at I_C=1 A / I_B=50 mA and h_FE = 400 at I_C=3 A - used in flash gun converters and battery-powered DC-DC boost stages.

For engineers reviewing the FZT688BTA datasheet, FZT688BTA pinout, FZT688BTA application, or FZT688BTA equivalent, key selection criteria include saturation voltage at high current, gain stability across temperature (−55°C to +150°C), safe operating area limits, and SOT-223 thermal performance in compact portable power circuits.

Technical Context

This device operates as a medium-power NPN switching transistor with low V_CE(sat) (0.04–0.40 V across 0.1–4 A) and high DC current gain (h_FE = 500 min at 0.1 A, 400 typ at 3 A). Its f_T = 150 MHz supports fast switching in pulsed DC-DC topologies.

Designed for operation under pulsed conditions (300 µs pulse width, ≤2% duty cycle), it features robust thermal capability (T_j up to +150°C), low input/output capacitance (C_ibo = 200 pF, C_obo = 40 pF), and tight V_BE(sat) = 1.1 V at I_C=3 A / I_B=20 mA - enabling efficient base drive in space-constrained battery systems.

Key Specifications

Pinout & Package

SOT-223 package with exposed emitter pad for thermal enhancement; standard 4-pin outline (3 active terminals + tab), lead-free and RoHS compliant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ZXTN2012GTA and MJD122G, FZT688BTA uniquely balances ultra-low saturation voltage, high gain at 3 A, and SOT-223 thermal efficiency - making it optimal for compact, battery-driven switching where both conduction loss and drive simplicity are critical.

Availability

FZT688BTA is available at Aetrix Electronics and suitable for flash gun converters, battery-powered DC-DC boost circuits, and portable LED driver designs requiring stable component supply and long-term manufacturability.

Supply support for FZT688BTA 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 and manufacturing operations across Asia and the Americas.

FZT688BTA belongs to the FZT series of high-gain medium-power transistors engineered specifically for portable and battery-operated power conversion applications demanding low-loss switching and thermal efficiency in small-outline packages.

FAQ

What is the maximum pulsed collector current rating for FZT688BTA?

The absolute maximum pulsed collector current (I_CM) is 10 A, specified under pulsed conditions: 300 µs pulse width and ≤2% duty cycle. This rating applies to short-duration surge events such as flash capacitor discharge, not continuous operation. Thermal limits still apply - junction temperature must remain below +150°C even during pulses.

Can FZT688BTA replace a standard 2N2222 in high-current switching?

No - while both are NPN transistors, FZT688BTA is rated for 4 A continuous and optimized for medium-power switching, whereas 2N2222 is limited to 800 mA and lacks the gain stability and low V_CE(sat) needed above 500 mA. Substitution would risk thermal runaway or insufficient drive in ≥1 A applications.

Is the SOT-223 package thermally adequate for 2 W dissipation?

Yes - when mounted with the emitter tab soldered to ≥100 mm² of 2-oz copper on an internal layer, the SOT-223 package achieves θ_JA ≈ 62°C/W, allowing safe 2 W operation at 25°C ambient. Without thermal pad connection, power must be derated to ≤0.5 W to avoid exceeding T_j = +150°C.

Does FZT688BTA have built-in ESD protection?

No - the device has no integrated ESD protection diodes. Per the datasheet, ESD sensitivity is typical for silicon planar transistors (HBM Class 1B, <500 V). Board-level TVS or series resistors are recommended in handling and circuit interfaces where static discharge risk exists, especially in portable assembly environments.