Diodes Incorporated FCX605TA

Overview

FCX605TA from Diodes Incorporated is a 120V NPN high-voltage Darlington transistor in SOT89 package, delivering 1A continuous collector current, V_CE(sat) < 1.5V at 1A, and DC current gain h_FE > 2000 at 1A - designed for robust switching of inductive loads such as relays, solenoids, and DC motors in industrial control modules.

For engineers reviewing the FCX605TA datasheet, FCX605TA pinout, FCX605TA application, or FCX605TA equivalent, key selection criteria include high-voltage blocking (120V V_CEO), low-saturation drive capability, AEC-Q101 qualification, thermal resistance (R_θJL = 5.2°C/W), and SOT89 lead-frame thermal performance under sustained 1A load conditions.

Technical Context

This Darlington pair integrates a driver and output transistor to achieve high current gain while maintaining single-package simplicity. It operates with V_CEO = 120V and V_CBO = 140V, enabling use in 100V-class DC bus switching where voltage transients exceed standard NPN ratings.

Its low V_BE(sat) = 1.8V and V_CE(sat) ≤ 1.5V at I_C = 1A reduce base drive power and conduction losses. The device features R_θJL = 5.2°C/W to the leads - critical for thermal management in PCB-mounted high-current switches without heatsinks.

Key Specifications

Pinout & Package

SOT89 package with exposed collector pad for enhanced thermal conduction; molded green compound (UL 94V-0), matte tin-plated leads, moisture sensitivity level 1.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-voltage Darlington switching applications.

Compared with ZTX1051A and BCX69-16, FCX605TA provides superior voltage margin (120V vs. ≤100V), higher current gain (>2000 vs. ≤1000), and automotive-grade reliability - making it the preferred choice for industrial and automotive 24–48V control systems requiring long-term robustness.

Availability

FCX605TA is available at Aetrix Electronics and suitable for industrial PLC output stages, automotive body control modules, DC motor drivers, and high-reliability lamp/solenoid drivers requiring stable component supply across multi-year production cycles.

Supply support for FCX605TA 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 power management, signal integrity, and protection solutions for industrial, automotive, and consumer markets.

The FCX605TA belongs to Diodes' high-voltage bipolar transistor product line, engineered specifically for ruggedized switching in harsh-environment control applications where voltage margin, thermal efficiency, and qualification compliance are mandatory.

FAQ

What is the maximum safe operating voltage for FCX605TA in continuous DC applications?

The FCX605TA is rated for V_CEO = 120V and V_CBO = 140V. For continuous DC operation, the recommended maximum collector-emitter voltage is 100V to maintain safety margin against transients and temperature derating. At +125°C junction temperature, V_CEO derates to approximately 95V per datasheet curves.

Can FCX605TA be used in high-frequency PWM motor control?

FCX605TA has f_T = 150MHz but is optimized for switching frequencies ≤20kHz. Its turn-off time t_OFF = 1.6µs limits practical PWM use to ≤50kHz with adequate dead-time. For >100kHz operation, MOSFET alternatives with lower gate charge are recommended.

Does FCX605TA require a base resistor when driven by a 3.3V microcontroller GPIO?

Yes - a base resistor is required to limit I_B to ~1mA for 1A I_C. With V_BE(ON) ≈ 1.7V, a 1.5kΩ resistor ensures proper saturation while protecting the GPIO. Omitting it risks excessive base current and potential damage to both MCU and transistor.

How does the SOT89 package's thermal performance compare to TO-92 for this device?

The SOT89's exposed collector tab delivers R_θJL = 5.2°C/W - over 5× better than TO-92's typical R_θJA > 200°C/W. This allows FCX605TA to dissipate 0.9W continuously in SOT89 with minimal PCB copper, whereas TO-92 would require large heatsinks or forced air for the same load.