onsemi NST3904MX2T5G

Overview

NST3904MX2T5G from onsemi is an NPN silicon general-purpose transistor in a 1.0 mm × 0.6 mm X2DFN3 package, rated for V_CEO = 40 V, I_C = 200 mA continuous, and f_T = 250 MHz. It delivers low V_CE(sat) (0.2 V at I_C = 10 mA/I_B = 1 mA) and supports fast switching in compact power management and signal amplification circuits.

For engineers reviewing the NST3904MX2T5G datasheet, pinout, applications, or equivalent options, key selection criteria include its thermal resistance (R_JA = 203 °C/W with 100 mm² copper pad), DC current gain range (h_FE = 30–300), and Pb-free RoHS-compliant construction for space-constrained industrial and consumer PCBs.

Technical Context

This NPN bipolar junction transistor operates in linear amplification and saturated switching modes, with verified performance across −55 °C to +150 °C junction temperature. Its small-signal parameters-including h_fe = 100–400 at 1 kHz and C_obo ≤ 4.0 pF-support high-frequency biasing and RF-coupled preamplifier stages.

The device uses surface-mount X2DFN3 packaging with thermally enhanced layout requirements: maximum power dissipation rises from 165 mW (0.6 mm² pad) to 590 mW (100 mm² pad), directly linking thermal design to safe operating area (SOA) compliance under pulsed load conditions.

Key Specifications

Pinout & Package

Package: X2DFN3 (1.0 mm × 0.6 mm, 0.35 mm pitch), Case 714AC, bottom-side thermal pad. Surface-mount only; no leads.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MMBT3904LT1G and DXT3904TC-7, the NST3904MX2T5G offers the smallest footprint (0.6 mm²), lowest thermal resistance (203 °C/W), and highest f_T, making it optimal for ultra-compact, high-speed, or thermally demanding NPN switching roles.

Availability

NST3904MX2T5G is available at Aetrix Electronics and suitable for LED drivers, microcontroller interface circuits, power supply enable switches, and level translation interfaces requiring stable component supply and long-term manufacturability.

Supply support for NST3904MX2T5G 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

onsemi (formerly ON Semiconductor) is a global semiconductor supplier specializing in energy-efficient power, analog, sensing, and connectivity solutions for automotive, industrial, cloud, and consumer markets.

The NST3904MX2T5G belongs to onsemi's general-purpose bipolar transistor family, engineered for miniaturized, high-reliability discrete switching and amplification in space-constrained applications where thermal performance and RoHS compliance are critical.

FAQ

What is the maximum continuous collector current for the NST3904MX2T5G?

The NST3904MX2T5G supports a maximum continuous collector current of 200 mA at T_A = 25 °C with proper PCB thermal management (100 mm² 2 oz. Cu pad). At elevated ambient temperatures, derating applies at 4.93 mW/°C above 25 °C, limiting usable current in high-temperature enclosures unless heatsinking is added.

Does the NST3904MX2T5G have a thermal pad, and is it electrically connected?

Yes, the NST3904MX2T5G in X2DFN3 package includes an exposed thermal pad on the bottom side, which is internally connected to the collector terminal. This pad must be soldered to a dedicated PCB copper area to achieve the 590 mW power rating and 203 °C/W thermal resistance specified in the datasheet.

Can the NST3904MX2T5G replace traditional TO-92 transistors like the 2N3904 in new designs?

The NST3904MX2T5G provides identical electrical characteristics to the 2N3904 but in a 0.6 mm² X2DFN3 package versus TO-92's 25 mm² footprint. It is not pin-compatible due to different pinout and mounting method; redesign of layout and stencil is required, though circuit topology remains unchanged.

What is the typical DC current gain (h_FE) of the NST3904MX2T5G at 100 mA collector current?

At I_C = 100 mA and V_CE = 1.0 V, the NST3904MX2T5G exhibits a typical h_FE of 30, with a guaranteed minimum of 30 per datasheet. This reduced gain at high current reflects optimized saturation behavior rather than degradation, supporting robust switching performance.

Is the NST3904MX2T5G suitable for RF amplifier applications?

The NST3904MX2T5G has an f_T of 250 MHz and low capacitance (C_obo ≤ 4.0 pF, C_ibo ≤ 8.0 pF), enabling use in narrowband RF preamplifiers up to ~100 MHz. However, it lacks specified noise figure or S-parameter data beyond 100 MHz, so broadband or high-linearity RF stages require characterization or alternative devices.