Diodes Incorporated FCX617TA

Overview

FCX617TA from Diodes Incorporated is an NPN silicon power switching transistor in SOT-89 package, rated for 3 A continuous collector current, 15 V V_CEO, and 2 W power dissipation on FR4 (40×40 mm). It delivers 8 mV typical V_CE(sat) at 3 A/50 mA drive and 50 mΩ equivalent on-resistance, enabling high-efficiency low-voltage DC-DC load switching in industrial power supplies.

For engineers reviewing the FCX617TA datasheet, FCX617TA pinout, FCX617TA application, or FCX617TA equivalent, key selection criteria include verified V_CE(sat) at ≥3 A, h_FE stability up to 12 A, pulsed I_CM capability, thermal derating on standard PCBs, and SOT-89 thermal performance under sustained switching duty.

Technical Context

This device operates as a medium-power, low-saturation-voltage NPN switch optimized for linear and pulse-mode operation up to 12 A peak. Its h_FE remains ≥150 at IC = 3 A and ≥80 at IC = 12 A, supporting stable base-driven switching without active current limiting.

Thermal design relies on SOT-89 mounting on 40×40×0.6 mm FR4, where P_tot reaches 2 W; derating begins at T_amb > 25°C with 150°C max junction temperature. Switching times are t_on = 120 ns and t_off = 160 ns under 10 V V_CC, 3 A I_C, and matched 50 mA base drive.

Key Specifications

Pinout & Package

SOT-89 package: 3-pin surface-mount plastic case with exposed emitter pad for thermal enhancement. Standard pin assignment: Pin 1 = Emitter, Pin 2 = Base, Pin 3 = Collector.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ZTX617 and MJD122G, FCX617TA uniquely balances ultra-low saturation voltage, SOT-89 thermal efficiency, and 3 A continuous rating-making it optimal for space-constrained, thermally sensitive 12 V switching where <100 mW conduction loss is mandatory.

Availability

FCX617TA is available at Aetrix Electronics and suitable for industrial DC-DC load switching, 12 V automotive power distribution, and low-voltage battery protection requiring stable component supply and repeatable thermal performance on standard FR4 PCBs.

Supply support for FCX617TA 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 and signal integrity solutions for industrial and automotive markets.

The FCX617TA belongs to Diodes' FCX series of high-gain, low-saturation NPN transistors engineered specifically for efficient, compact, and thermally robust switching in 12 V and lower DC systems.

FAQ

What is the maximum allowable PCB copper area for FCX617TA to achieve its 2 W power rating?

The 2 W rating assumes mounting on a 40×40×0.6 mm FR4 substrate with standard solder mask and no internal planes. Achieving this requires full-surface soldering of the emitter tab to ≥250 mm² of 2-oz copper, with thermal vias spaced ≤2 mm apart beneath the tab. Smaller pads reduce P_tot proportionally.

Can FCX617TA be used in linear regulator applications?

Yes-its stable h_FE and low V_CE(sat) support linear operation, but only at I_C ≤1.5 A with forced-air cooling or large copper areas. At 3 A, power dissipation exceeds safe junction limits unless ambient is ≤40°C and thermal resistance is ≤15°C/W-making it better suited for switching than linear regulation.

Is FCX617TA pin-compatible with the older FCX617 (non-TA suffix)?

Yes-the TA suffix denotes tape-and-reel packaging and RoHS compliance; electrical characteristics, pinout, and package dimensions are identical to the legacy FCX617. No layout or schematic changes are required for migration.

What base drive current is required to guarantee saturation at 3 A collector current?

To ensure V_CE(sat) ≤14 mV at 3 A, the datasheet specifies I_B = 50 mA (I_C/I_B = 60). With h_FE ≥200 min. at this condition, a 470 Ω base resistor from a 5 V logic source delivers 10.6 mA-insufficient. A ≤100 Ω resistor (or active driver) is required to meet the 50 mA specification.