Diodes Incorporated FMMTA42QTA

Overview

FMMTA42QTA from Diodes Incorporated is a 300V NPN high-voltage transistor in SOT23 package, designed for switching and amplification in high-breakdown-voltage applications. It delivers 200mA collector current, 350mW power dissipation, and exhibits hFE of 25–40 at IC = 1–30mA with VCE = 10V. Used in flyback snubber circuits, relay drivers, and HV DC-DC bias supplies.

For engineers reviewing the FMMTA42QTA datasheet, FMMTA42QTA pinout, FMMTA42QTA application, or FMMTA42QTA equivalent, key selection criteria include BVCEO ≥ 300V, IC = 200mA, VCE(sat) ≤ 500mV at IC = 20mA/IB = 2mA, fT = 50MHz, and SOT23 thermal resistance RθJA = 357°C/W on 15mm × 15mm copper.

Technical Context

This NPN bipolar junction transistor operates with a minimum collector-emitter breakdown voltage of 300V and supports continuous collector currents up to 200mA. Its transition frequency of 50MHz enables use in medium-speed switching and signal amplification above audio bands.

The device features low saturation voltages-VCE(sat) ≤ 500mV and VBE(sat) ≤ 900mV under 20mA/2mA drive-and maintains stable hFE across 1–30mA IC range, supporting predictable gain control in linear and switching modes.

Key Specifications

Pinout & Package

Package: SOT23 - Surface-mount plastic package with 0.915mm lead pitch, 2.40mm body length, and UL 94V-0 flammability rating. Matte tin-plated leads ensure solderability per MIL-STD-202 Method 208.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar NPN high-voltage transistor applications.

Compared with MMBT4401 and FMMTA92, FMMTA42QTA uniquely balances 300V breakdown, 200mA drive, and SOT23 footprint-making it the only option among the three for 200–300V DC switching where space and voltage margin are critical.

Availability

FMMTA42QTA is available at Aetrix Electronics and suitable for industrial power supply snubbers, automotive LED driver switches, and AC-DC adapter bias supplies requiring stable component supply and long-term manufacturability.

Supply support for FMMTA42QTA 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, serving industrial, computing, consumer, and automotive markets with high-reliability components.

FMMTA42QTA belongs to Diodes' high-voltage bipolar transistor product line, engineered specifically for cost-sensitive, space-constrained applications demanding robust 300V breakdown performance in SOT23.

FAQ

What is the maximum continuous collector current for FMMTA42QTA?

The absolute maximum continuous collector current is 200mA at TA = +25°C. Derating applies above 25°C ambient: power dissipation drops linearly to zero at +150°C junction temperature, per the 357°C/W RθJA rating on 15mm × 15mm copper.

Is FMMTA42QTA suitable for automotive applications?

FMMTA42QTA is not AEC-Q101 qualified. Diodes offers the automotive-compliant variant FMMTA42Q (separate datasheet), which undergoes stress testing per AEC-Q101 and supports extended temperature operation from −40°C to +150°C.

What is the typical hFE at 10mA collector current?

At IC = 10mA, VCE = 10V, and TA = +25°C, the typical hFE is 40, with a guaranteed minimum of 25. This value remains stable across the 1–30mA range, simplifying base resistor calculation for saturation switching.

Does FMMTA42QTA require a heatsink in standard SOT23 mounting?

No heatsink is required. With PD = 350mW and RθJA = 357°C/W on a 15mm × 15mm 1oz copper pad, junction-to-ambient rise is ~125°C at full power-within the −55°C to +150°C operating range if ambient stays below +25°C. For sustained 350mW, reduce ambient or increase copper area.