Diodes Incorporated FMMT625TC

Overview

FMMT625 from Diodes Incorporated is a 150V NPN silicon low-saturation transistor in SOT23 package, designed for high-voltage switching in power management circuits. It delivers 1A continuous collector current, 625mW power dissipation, and V_CE(SAT) as low as 26mV at I_C = 0.1A / I_B = 10mA - enabling efficient operation in DC-DC modules and motor drive stages.

For engineers reviewing the FMMT625 datasheet, FMMT625 pinout, FMMT625 application, or FMMT625 equivalent, key selection criteria include its AEC-Q101 qualification, 150V BV_CEO, h_FE up to 450 at 1A, 8kV HBM ESD rating, and thermal resistance of 200°C/W - all critical for automotive-grade power switching reliability.

Technical Context

This NPN transistor operates with a minimum BV_CEO of 150V and supports pulsed collector currents up to 3A. Its h_FE is fully characterized from 10mA to 3.0A, ensuring predictable gain across load ranges in switching applications.

V_CE(SAT) remains below 300mV at I_C = 1A / I_B = 50mA, and f_T reaches 135MHz, confirming suitability for medium-frequency switching (e.g., <500kHz PWM) in compact power converters.

Key Specifications

Pinout & Package

Package: SOT23 - surface-mount plastic case, 0.008g weight, UL 94V-0 rated, moisture sensitivity level 1.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ZXTN25050DFH, FMMT625 trades 50V voltage headroom for broader automotive qualification; versus MMBT625, it adds AEC-Q101 validation without electrical compromise - making it optimal for safety-critical 12V/24V vehicle subsystems.

Availability

FMMT625 is available at Aetrix Electronics and suitable for DC-DC modules, motor control functions, and automotive body electronics requiring stable component supply across production lifecycles.

Supply support for FMMT625 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, manufacturing, and sales operations across Asia, Europe, and North America.

FMMT625 belongs to Diodes' high-reliability discrete transistor product line, engineered specifically for automotive and industrial power switching where voltage robustness, thermal stability, and qualification compliance are mandatory.

FAQ

What is the maximum safe operating voltage for FMMT625 in continuous mode?

The absolute maximum collector-emitter voltage (V_CEO) is 150V at T_A = 25°C. Derating is required above 25°C ambient: linear reduction to 0V at 150°C junction temperature per the datasheet's Safe Operating Area curve. Operation above 130V is not recommended without transient clamping for inductive loads.

Can FMMT625 replace a general-purpose NPN transistor like BC817 in a 12V motor driver?

Yes - but only if the application demands ≥150V breakdown or AEC-Q101 qualification. FMMT625 offers superior V_CEO, lower V_CE(SAT), and automotive qualification versus BC817, though its h_FE is optimized for higher currents (1A–3A). For 100mA loads, BC817 may be more cost-effective.

Does FMMT625 require a heatsink in SOT23 footprint applications?

No external heatsink is required under typical conditions: at 1A I_C and 25°C ambient, junction temperature rise is ~125°C (R_θJA × P_D ≈ 200°C/W × 0.3W), staying within the 150°C limit only with significant derating. For sustained 1A operation, use 25mm × 25mm copper pour and limit duty cycle or ambient to ≤50°C.

Is the FMMT625Q variant pin-compatible with FMMT625?

Yes - FMMT625Q uses the identical SOT23-3 package and pinout (Emitter-Base-Collector on pins 1–2–3), with identical electrical specifications. The Q suffix denotes AEC-Q101 qualification and traceability enhancements; both share the same 625 marking and mechanical dimensions.