Diodes Incorporated MMSTA14-7-F

Overview

MMSTA14-7-F 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-F datasheet, MMSTA14-7-F pinout, MMSTA14-7-F application, or MMSTA14-7-F equivalent, key selection criteria include Darlington current gain, V_CE(SAT) ≤ 1.5 V at 100 mA/100 µA drive, SOT-323 thermal resistance (625 °C/W), and RoHS-compliant green molding compound compliance per J-STD-020C Level 1 moisture sensitivity.

Technical Context

This Darlington pair integrates two NPN transistors monolithically to deliver high DC current gain while maintaining low base drive requirements. It operates with V_EB ≤ 10 V and supports continuous collector currents up to 300 mA at T_A = 25°C on standard FR-4 PCBs.

The device exhibits f_T = 125 MHz at V_CE = 5 V and I_C = 10 mA, enabling use in medium-speed switching applications. Its C_obo = 8.0 pF and C_ibo = 15 pF support stable operation in low-noise analog front-ends and digital logic interfacing.

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, lead-free matte tin plating, moisture sensitivity Level 1.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MMSTA13-7-F and BC817-40,215, MMSTA14-7-F uniquely delivers ultra-high DC gain with Darlington architecture-enabling microampere-level control of 100 mA loads-while maintaining SOT-323 compatibility and thermal performance suitable for space-constrained, low-power embedded systems.

Availability

MMSTA14-7-F is available at Aetrix Electronics and suitable for LED driver circuits, sensor signal amplification, low-power relay drivers, and microcontroller I/O interface applications requiring stable component supply and RoHS-compliant packaging.

Supply support for MMSTA14-7-F 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, energy-efficient components for consumer, industrial, and automotive markets.

MMSTA14-7-F belongs to Diodes' general-purpose bipolar transistor product line, designed specifically for low-power amplification and switching in space-constrained, cost-sensitive applications where high current gain and compact packaging are critical.

FAQ

What is the maximum allowable collector current for MMSTA14-7-F at 85°C ambient?

At T_A = 85°C, derated power dissipation limits I_C to approximately 120 mA. This is calculated using P_D = 200 mW × (1 − (85−25)/625) ≈ 120 mW, and assuming V_CE(SAT) ≈ 1.5 V yields I_C ≈ 80 mA continuous; however, peak pulsed current remains 300 mA per datasheet absolute maximum ratings.

Is MMSTA14-7-F pin-compatible with SOT-23 packaged Darlington transistors?

No. MMSTA14-7-F uses SOT-323 (3-pin, 2.2 mm × 1.35 mm), whereas SOT-23 packages are larger (2.9 mm × 1.3 mm) and have different pin spacing. Pin 1 (Emitter), Pin 2 (Base), Pin 3 (Collector) assignment matches JEDEC TO-236AB, but mechanical fit and solder pad layout are not interchangeable.

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

Yes. A series base resistor is mandatory to limit I_B and ensure proper saturation. For 100 mA I_C, target I_B ≥ 100 µA; with V_BE(SAT) ≈ 2.0 V and 3.3 V drive, a 10 kΩ resistor provides ~130 µA, satisfying minimum drive requirement while avoiding excessive base current.

How does the "Green" molding compound affect long-term reliability?

Post-2006 "Green" compound eliminates halogens and antimony trioxide, improving flame retardancy (UL 94V-0) and reducing corrosion risk in humid environments. Accelerated life testing shows no degradation in h_FE, leakage, or thermal resistance versus non-Green versions, confirming equivalent long-term reliability.