Diodes Incorporated FMMT6517TC

Overview

FMMT6517TC from Diodes Incorporated is a 350V NPN high-voltage transistor in SOT23 package, rated for 500mA collector current and 350mW power dissipation, with hFE ≥20 at IC=1mA/VCE=10V and BVCEO = 350V. It serves as a high-voltage switching element in flyback converters, LED drivers, and industrial control interfaces where robust voltage blocking and AEC-Q101 reliability are required.

For engineers reviewing the FMMT6517TC datasheet, FMMT6517TC pinout, FMMT6517TC application, or FMMT6517TC equivalent, key selection criteria include verified 350V VCEO rating, SOT23 thermal resistance (RθJA = 403°C/W on minimal pad), ICBO ≤50nA at 250V, and complementary pairing with FMMT6520 for push-pull topologies.

Technical Context

This NPN bipolar junction transistor operates with a minimum BVCEO of 350V and supports continuous collector currents up to 500mA. Its hFE ranges from 20–200 depending on bias conditions (IC = 1mA to 100mA, VCE = 10V), and it delivers VCE(SAT) ≤0.35V at IC = 20mA/IB = 2mA.

Designed for high-voltage switching, it features low output capacitance (COBO = 6pF at VCB = 20V), fT = 50MHz, and ESD robustness (HBM = 4kV). Thermal performance is specified for both minimum-pad (RθJA = 403°C/W) and enhanced-pad (RθJA = 357°C/W) PCB layouts.

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 high-voltage NPN transistor applications.

Compared with ZTX653 and FMMT6520, FMMT6517TC uniquely balances 350V capability, SOT23 size, and AEC-Q101 compliance-making it optimal for space-constrained, high-reliability 230VAC-derived or automotive 12V systems where voltage margin and qualification matter more than raw power.

Availability

FMMT6517TC is available at Aetrix Electronics and suitable for industrial power supplies, automotive lighting control, relay driver modules, and high-voltage sensor interfaces requiring stable component supply and long-term lifecycle support.

Supply support for FMMT6517TC 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.

FMMT6517TC belongs to Diodes' high-voltage bipolar transistor product line, engineered specifically for ruggedized switching in automotive, industrial, and appliance power systems where reliability under voltage stress and thermal cycling is critical.

FAQ

What is the maximum safe operating voltage for FMMT6517TC in continuous DC mode?

The absolute maximum collector-emitter voltage (VCEO) is 350V at TA = +25°C. Derating is required above 25°C: RθJA = 403°C/W implies ~0.87V/°C reduction in allowable VCEO per watt of dissipation. At 100°C ambient and 310mW dissipation, safe VCEO drops to approximately 315V.

Does FMMT6517TC require a base resistor for microcontroller GPIO drive?

Yes. With hFE = 20–200 and IC up to 500mA, a base resistor is mandatory to limit IB and ensure saturation. For example, driving 100mA collector current at hFE = 20 requires IB = 5mA; with 3.3V GPIO and VBE(SAT) ≈ 0.85V, a 470Ω resistor sets appropriate base current while avoiding GPIO overload.

How does the SOT23 package affect thermal performance in high-voltage switching?

The SOT23 package limits thermal dissipation to 310–350mW depending on PCB copper area. Its RθJA = 403°C/W on minimal pads means even 200mW dissipation raises junction temperature by ~81°C above ambient. Layout must use thermal vias and extended copper pours to avoid exceeding TJ(max) = +150°C in sustained operation.

Is FMMT6517TC suitable for linear-mode (non-switching) amplification?

It can operate linearly, but its COBO = 6pF and fT = 50MHz make it suitable only for low-bandwidth, high-voltage gain stages (e.g., <1MHz). Power dissipation must be strictly limited: at VCE = 200V and IC = 1mA, PD = 200mW - already near half its rated limit, demanding careful thermal design.