Diodes Incorporated FCX491TA

Overview

FCX491TA from Diodes Incorporated is a 60V NPN medium-power transistor in SOT89 package, rated for 1A continuous collector current and 2A peak pulse current, with V_CE(sat) ≤ 250 mV at I_C = 1A / I_B = 100mA, h_FE ≥ 30 at 2A, and qualified to AEC-Q101 for automotive reliability. It serves as a robust switching element in DC-DC converter primary-side drivers and industrial motor control interface stages.

For engineers reviewing the FCX491TA datasheet, FCX491TA pinout, FCX491TA application, or FCX491TA equivalent, key selection criteria include its 60V V_CEO, low R_CE(sat) of 195 mΩ, thermal resistance R_θJC = 16°C/W, AEC-Q101 qualification, and complementary PNP pairing with FCX591TA in push-pull configurations.

Technical Context

This NPN bipolar junction transistor operates in linear or saturated switching modes with guaranteed gain (h_FE) from 100 at 1mA up to 30 at 2A, supporting stable current amplification across wide load ranges. Its 80V V_CBO and 7V V_EBO provide margin against transient overvoltage in inductive load switching.

Thermal performance is defined by three mounting conditions: R_θJA = 125°C/W on 15mm × 15mm 1oz copper, down to 60°C/W on 50mm × 50mm - enabling precise power derating in space-constrained PCB layouts. Transient thermal impedance curves support pulsed operation up to 2A with controlled junction temperature rise.

Key Specifications

Pinout & Package

Package: SOT89 - surface-mount plastic package with exposed collector pad for thermal dissipation; dimensions per AP02002 (4.50 × 2.50 × 1.50 mm), moisture sensitivity level 1.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ZXTN25040DFH and MJD122G, FCX491TA uniquely balances AEC-Q101 qualification, SOT89 thermal performance (2W capability), and 1A/60V rating - making it optimal for space-constrained automotive and industrial switching where reliability and thermal density are co-prioritized.

Availability

FCX491TA is available at Aetrix Electronics and suitable for automotive body control modules, industrial PLC output stages, and DC-DC converter designs requiring stable component supply with AEC-Q101 assurance and consistent SOT89 thermal behavior.

Supply support for FCX491TA 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 components for automotive, industrial, and computing markets since 1966.

The FCX491TA belongs to Diodes' FCX series of medium-power transistors designed specifically for AEC-Q101-compliant automotive switching and industrial interface applications demanding robust thermal performance in compact SOT89 packages.

FAQ

What is the maximum allowable junction temperature for FCX491TA?

The absolute maximum junction temperature is +150°C, as specified in the Absolute Maximum Ratings table. Operation above this limit risks permanent degradation of h_FE and increased leakage. Derating curves show that at 100°C ambient, maximum continuous power drops to ~0.8W on 15mm × 15mm copper - requiring thermal design verification per application conditions.

Is FCX491TA pin-compatible with FCX591TA?

No - FCX491TA (NPN) and FCX591TA (PNP) share the same SOT89 package and pinout order (C-E-B), but their complementary polarity means they cannot substitute directly. They are intended for paired use in push-pull or H-bridge topologies where matched thermal and electrical characteristics are required across both polarities.

Does FCX491TA require a base resistor in switching applications?

Yes - a base resistor is mandatory to limit I_B and ensure saturation. For 1A I_C, h_FE ≥ 30 requires ≥33 mA I_B; with V_BE(sat) ≈ 1.1 V and 3.3V/5V logic drive, a 68 Ω (for 5V) or 120 Ω (for 3.3V) resistor ensures reliable turn-on while avoiding excessive base current dissipation.

Can FCX491TA be used in linear amplifier configurations?

Yes - its h_FE is characterized from 1mA to 2A and f_T = 150 MHz supports small-signal amplification up to ~15 MHz. However, linear operation demands strict thermal management: at 500 mW dissipation, junction temperature rise exceeds 30°C even on 50mm × 50mm copper, limiting practical use to low-power, short-duration analog functions.