Diodes Incorporated FZT655TC

Overview

FZT655 from Diodes Incorporated is a 150V NPN medium-power transistor in SOT223 package, rated for 1A continuous collector current and featuring V_CE(sat) = 120 mV (typ.) at I_C = 500 mA / I_B = 50 mA. It delivers high-voltage switching capability with low saturation voltage and is commonly used in DC-DC converter primary-side switches and industrial power supply control stages.

For engineers reviewing the FZT655 datasheet, FZT655 pinout, FZT655 application, or FZT655 equivalent, key selection criteria include its 150V V_CEO, 2 W power dissipation on 25 mm × 25 mm PCB, h_FE = 50–300 across operating range, and thermal resistance R_θJA = 62.5 °C/W - critical for thermal design in compact power circuits.

Technical Context

The FZT655 is a silicon NPN bipolar junction transistor optimized for medium-power linear and switching applications where high breakdown voltage and stable DC gain are required. Its BV_CEO = 150 V and BV_CBO = 150 V support operation in 100–120 V DC bus environments, while f_T = 30 MHz enables use in moderate-frequency switching up to ~100 kHz with minimal gain roll-off.

Thermal performance is defined by two mounting conditions: R_θJA = 62.5 °C/W (25 mm × 25 mm 2 oz Cu) and 41.7 °C/W (50 mm × 50 mm), with R_θJL = 19.41 °C/W confirming efficient heat conduction through the collector lead - essential for reliability in thermally constrained layouts.

Key Specifications

Pinout & Package

Package: SOT223 (Type DN), surface-mount, 4-pin configuration with emitter-connected tab (pin 3) serving as thermal and electrical ground reference. Molded green compound, UL 94V-0 rated, matte tin-plated leads.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ZXTN2012E6TA and MJD122G, the FZT655 uniquely balances 150 V capability, 1 A current, and SOT223 thermal performance - making it optimal for compact, high-input-voltage industrial power stages where voltage margin and PCB-level thermal management are both critical.

Availability

FZT655 is available at Aetrix Electronics and suitable for industrial power supply control, DC-DC converter switching, and relay driver circuits requiring stable component supply and long-term manufacturing continuity.

Supply support for FZT655 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 distribution operations across Asia, Europe, and North America.

The FZT655 belongs to Diodes' high-voltage bipolar transistor product line, engineered specifically for industrial and automotive-grade power control applications demanding robustness, thermal efficiency, and AEC-Q101 readiness.

FAQ

What is the maximum safe operating temperature for FZT655?

The FZT655 has an operating junction temperature range of –55°C to +150°C. With R_θJA = 62.5 °C/W on a 25 mm × 25 mm 2 oz copper PCB, sustained 2 W dissipation limits ambient temperature to +25°C for T_J ≤ 150°C. Derating curves in DS33151 show linear reduction above +25°C ambient.

Is FZT655 qualified for automotive applications?

The FZT655 is not AEC-Q101 qualified out-of-the-box, but Diodes states that automotive-grade versions with PPAP capability and IATF 16949 manufacturing are available upon request. Standard FZT655 meets RoHS, halogen-free, and JEDEC ESD specifications required for many Tier-2 automotive subsystems.

How does the SOT223 pin 4 (tab) connect electrically?

Pin 4 is the exposed metal tab, internally connected to the emitter terminal. It serves as both a low-inductance emitter return path and primary thermal conduction interface to the PCB copper pour. Electrical isolation from collector/base is maintained by internal die construction and mold compound.

Can FZT655 replace FZT653 in existing designs?

No - FZT653 has V_CEO = 100 V and h_FE = 20–120, while FZT655 offers 150 V rating and h_FE = 50–300. Substitution may cause premature failure in >100 V applications; redesign verification is required for voltage margin, gain stability, and thermal response.