Diodes Incorporated MMSTA14-7

Overview

MMSTA14-7 from Diodes Incorporated is an NPN surface-mount Darlington transistor in SOT-323 package, rated for 30 V V_CEO, 300 mA I_C, and 200 mW P_D, with h_FE = 10,000–20,000 at I_C = 10–100 mA, used in low-power switching and amplification circuits such as LED drivers and sensor interface stages.

For engineers reviewing the MMSTA14-7 datasheet, MMSTA14-7 pinout, MMSTA14-7 application, or MMSTA14-7 equivalent, key selection criteria include Darlington current gain, V_CE(SAT) ≤ 1.5 V at I_C = 100 mA/I_B = 100 μA, thermal resistance of 625 °C/W, RoHS-compliant green molding compound, and SOT-323 footprint compatibility with space-constrained PCB layouts.

Technical Context

This Darlington pair integrates two NPN transistors monolithically to achieve high DC current gain while maintaining single-device simplicity. It operates with V_EB ≤ 10 V and supports continuous collector currents up to 300 mA at T_A = 25°C, with derating above 25°C per Fig. 1.

The device exhibits f_T = 125 MHz at V_CE = 5 V and I_C = 10 mA, enabling use in medium-frequency signal amplification; C_obo = 8.0 pF and C_ibo = 15 pF support stable small-signal behavior in bias networks and low-noise preamp stages.

Key Specifications

Pinout & Package

Package: SOT-323 - ultra-small surface-mount plastic case (2.00–2.20 mm length × 1.15–1.35 mm width × 0.25–0.40 mm height), UL 94V-0 rated, moisture sensitivity level 1, lead-free matte tin plating.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MMSTA13-7-F, MMSTA14-7 offers double the minimum h_FE for same footprint and voltage ratings; versus BC817-40-7-F, it delivers >15× higher current gain but trades off bandwidth and saturation voltage-making it optimal for low-speed, high-gain switching rather than RF or fast digital use.

Availability

MMSTA14-7 is available at Aetrix Electronics and suitable for LED driver circuits, sensor interface amplifiers, low-power relay drivers, and microcontroller output expanders requiring stable component supply and long-term manufacturability.

Supply support for MMSTA14-7 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, with design centers and manufacturing facilities across Asia and the Americas.

The MMSTA14-7 belongs to Diodes' general-purpose bipolar transistor product line, engineered specifically for space-constrained, low-power switching and amplification applications in consumer, industrial, and computing end equipment.

FAQ

What is the maximum operating temperature for MMSTA14-7?

The MMSTA14-7 is rated for junction and storage temperatures from –55°C to +150°C. Its thermal resistance R_θJA = 625 °C/W means that at 200 mW dissipation on a standard FR-4 PCB, junction temperature rises 125°C above ambient-so maximum safe ambient is +25°C for full-power operation unless heatsinking or airflow is added.

Does MMSTA14-7 require a base resistor in switching applications?

Yes-a base resistor is mandatory to limit I_B and prevent damage. For example, driving a 100 mA load with h_FE = 10,000 requires ~10 μA base current; with a 3.3 V MCU GPIO, a 330 kΩ resistor provides appropriate bias while ensuring saturation. Omitting it risks excessive base current and thermal runaway.

Is MMSTA14-7 pin-compatible with other SOT-323 transistors?

Yes-MMSTA14-7 uses standard SOT-323 pinout (Emitter-Base-Collector, left-to-right when viewed from top with marking side up). It matches physical layout and terminal assignment of all industry-standard SOT-323 NPN transistors, including BC846, MMBT3904, and DXT751, though electrical characteristics differ significantly.

Can MMSTA14-7 be used in linear amplification mode?

Yes-it supports linear operation with V_CE biased between 1 V and 10 V and I_C set within 1–50 mA range. Its h_FE stability and low C_obo/C_ibo support predictable gain in Class-A audio preamps or sensor signal conditioners, but f_T = 125 MHz limits usable bandwidth to <10 MHz for stable closed-loop designs.