Diodes Incorporated FMMT734TC

Overview

FMMT734 from Diodes Incorporated is a 100V PNP Darlington transistor in SOT23 package, designed for high-gain switching and amplification in low-power analog and digital control circuits. It delivers -800mA continuous collector current, >20,000 hFE at -100mA, -100V VCEO rating, and 625mW power dissipation - enabling use in industrial relay drivers and automotive load switches.

For engineers reviewing the FMMT734 datasheet, FMMT734 pinout, FMMT734 application, or FMMT734 equivalent, key selection criteria include verified Darlington gain stability up to -5A, -0.72V VCE(sat) at -800mA/-5mA drive, SOT23 thermal resistance (RθJA = 200°C/W), and AEC-Q101 qualification for automotive-grade reliability.

Technical Context

This PNP Darlington pair integrates two cascaded transistors to achieve ultra-high DC current gain while maintaining single-device simplicity. Its structure supports robust saturation performance with VBE(sat) = -1.6V and VCE(sat) = -0.72V at -800mA/-5mA, enabling efficient low-side switching in space-constrained PCB layouts.

The device operates across -55°C to +150°C and features ESD ratings of 2,000V HBM and 200V MM. Its 140MHz fT and 14pF CobO support moderate-frequency switching applications, while the -12V VEBO rating ensures safe biasing in emitter-follower configurations.

Key Specifications

Pinout & Package

Package: SOT23 - surface-mount plastic case, 0.008g weight, UL 94V-0 rated, moisture sensitivity level 1, matte tin-plated leads solderable per MIL-STD-202.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ZTX951 and FMMT634, the FMMT734 uniquely combines AEC-Q101 qualification, SOT23 size, and Darlington gain stability up to -5A - making it optimal for automotive and industrial space-limited switching where reliability and gain consistency are prioritized over raw power handling.

Availability

FMMT734 is available at Aetrix Electronics and suitable for industrial relay drivers, automotive body control modules, LED current regulators, and low-power amplifier stages requiring stable component supply and long-term lifecycle assurance.

Supply support for FMMT734 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 and manufacturing operations across Asia and the Americas.

The FMMT734 belongs to Diodes' high-reliability discrete transistor product line, engineered specifically for automotive and industrial applications demanding AEC-Q101 compliance, high-voltage tolerance, and robust thermal performance in miniature packages.

FAQ

What is the maximum safe continuous collector current for FMMT734?

The FMMT734 is rated for -800mA continuous collector current at TA = +25°C with proper PCB thermal management (25mm × 25mm 1 oz copper). Derating applies linearly above +25°C ambient - at +100°C, max IC drops to approximately -400mA based on its 5mW/°C thermal coefficient and 625mW PD rating.

Does FMMT734 require a base resistor, and how is its value calculated?

Yes - a base resistor is mandatory to limit IB and prevent thermal runaway. For -800mA IC, typical IB = -5mA yields safe saturation. With VBE(on) ≈ -1.3V and MCU GPIO = 3.3V, RB = (3.3V − 1.3V)/5mA = 400Ω. A standard 390Ω resistor ensures adequate drive while accommodating process variation and temperature drift.

Can FMMT734 replace a standard PNP BJT in existing designs?

Only with circuit revision: Darlington topology introduces ~1.3V VBE(on) and slower switching (t(on)/t(off) = 460ns/1200ns). Direct substitution risks insufficient base drive, increased propagation delay, and potential latch-up in high-speed logic interfaces. Use only where high gain justifies trade-offs in speed and voltage overhead.

Is FMMT734 suitable for high-frequency switching above 1MHz?

It supports moderate-frequency operation up to ~10MHz due to its 140MHz fT and 14pF CobO, but t(off) = 1200ns limits practical PWM duty-cycle resolution. For >1MHz switching with fast transient response, consider RF-optimized PNP transistors or integrated drivers - the FMMT734 excels in <100kHz load switching where gain and voltage margin dominate.