Diodes Incorporated FMMT494QTC

Overview

FMMT494QTC from Diodes Incorporated is a 120V NPN silicon planar medium-power bipolar junction transistor (BJT) in SOT23 (Type DN) package, rated for 1A continuous collector current, 500mW power dissipation, and qualified to AEC-Q101 for automotive applications. It delivers high-current gain stability up to 1A (h_FE ≥20 at I_C = 1A), supports 140V V_CBO, and features 4kV HBM ESD rating - deployed in automotive body control modules for load switching.

For engineers reviewing the FMMT494QTC datasheet, FMMT494QTC pinout, FMMT494QTC application, or FMMT494QTC equivalent, key selection criteria include V_CEO ≥120V, I_C ≥1A continuous capability, AEC-Q101 qualification, thermal resistance R_θJA = 250°C/W on 15×15mm FR4, and SOT23 (DN) mechanical compatibility with automated assembly.

Technical Context

This NPN BJT operates as a medium-power switch in DC-coupled linear and pulse applications, with V_CEO = 120V and V_CBO = 140V enabling use in 24V/48V automotive supply rails. Its h_FE is characterized across 1mA–1A, maintaining ≥20 at full 1A load - critical for stable base drive design in high-side or low-side configurations.

V_CE(sat) ≤300mV at I_C = 500mA / I_B = 50mA ensures low conduction loss, while f_T = 100MHz supports fast switching up to ~100kHz PWM frequencies. The device's R_θJL = 197°C/W and JEDEC Level 1 moisture sensitivity support reflow-compatible manufacturing without preconditioning.

Key Specifications

Pinout & Package

SOT23 (Type DN) surface-mount plastic package, 0.008g weight, UL 94V-0 rated molding compound, matte tin-plated leads solderable per MIL-STD-202 Method 208.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ZXTN25050DFHTA and MMBT4401-7-F, FMMT494QTC uniquely combines 120V breakdown, AEC-Q101 qualification, and 1A continuous rating in SOT23 - making it the sole option for thermally constrained, high-reliability 24V+ automotive switching where both voltage headroom and qualification are mandatory.

Availability

FMMT494QTC is available at Aetrix Electronics and suitable for automotive body electronics, industrial 24V relay interfaces, and LED lighting control requiring stable component supply and long-term lifecycle assurance.

Supply support for FMMT494QTC 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.

FMMT494QTC belongs to Diodes' AEC-Q101-qualified medium-power BJT product line, engineered specifically for automotive load-switching applications demanding high V_CEO, stable h_FE at full current, and robust thermal performance in compact SOT23 packages.

FAQ

What is the maximum allowable continuous collector current for FMMT494QTC at 100°C ambient?

At T_A = 100°C, the device's maximum continuous collector current is derated to approximately 0.6A based on its 500mW power limit and R_θJA = 250°C/W. This assumes mounting on a 15×15mm FR4 board with 1oz copper; actual current must be reduced further if PCB copper area is smaller or airflow is restricted.

Is FMMT494QTC suitable for switching inductive loads like relays or solenoids?

Yes - its 120V V_CEO and 140V V_CBO provide sufficient margin against inductive kickback in 24V automotive systems. When used with a properly sized flyback diode (e.g., 1N4007), it reliably switches loads up to 1A DC with no secondary breakdown risk under specified pulse conditions.

Does FMMT494QTC require gate/base resistors in standard switching configurations?

Yes - a series base resistor is mandatory to limit I_B to ≤200mA (absolute max) and ensure proper saturation. For 1A I_C with h_FE ≥20, a 220Ω resistor from a 5V logic source delivers ~18mA I_B, achieving safe, low-V_CE(sat) operation without overstressing the base-emitter junction.

How does the "Green" designation impact FMMT494QTC's compliance and assembly process?

The "Green" status confirms halogen- and antimony-free composition (<900ppm Br/Cl, <1000ppm Sb), satisfying automotive OEM environmental requirements. It has no effect on solderability - matte tin plating meets MIL-STD-202 Method 208, and JEDEC Level 1 MSL eliminates need for baking prior to reflow.