Diodes Incorporated FMMTL618TA

Overview

FMMTL618TA from ON Semiconductor is an NPN silicon planar medium-power transistor in SOT-23 package, designed for high-gain switching and linear amplification with V_CEO = 20 V, I_C = 1.25 A, and h_FE ≥ 200 at I_C = 10 mA. It delivers low V_CE(sat) of 130 mV at I_C = 1.25 A / I_B = 100 mA and supports operation from –55°C to +150°C, commonly used in DC-DC converter power switches and load drivers.

For engineers reviewing the FMMTL618TA datasheet, FMMTL618TA pinout, FMMTL618TA application, or FMMTL618TA equivalent, key selection criteria include verified V_CE(sat) performance at 1.25 A, guaranteed h_FE minimum across temperature, SOT-23 thermal derating behavior, and complementary pairing with FMMTL718 for push-pull topologies.

Technical Context

This NPN bipolar junction transistor uses planar epitaxial construction to achieve stable gain and low saturation voltage under medium-current switching conditions. Its f_T of 195 MHz at I_C = 50 mA / V_CE = 10 V enables use in high-speed digital switching up to ~50 MHz, while C_obo = 9–12 pF supports predictable turn-on/turn-off timing.

The device operates with fixed base-emitter forward biasing (V_BE(on) = 850–1000 mV at I_C = 1.25 A), and its safe operating area (SOA) is defined up to 10 ms pulse width at T_amb = 25°C - critical for transient load handling in automotive body control modules and industrial relay drivers.

Key Specifications

Pinout & Package

SOT-23 plastic surface-mount package with standard pin assignment: Pin 1 = Emitter, Pin 2 = Base, Pin 3 = Collector. Compact 2.9 mm × 1.3 mm footprint supports high-density PCB layouts and automated reflow assembly.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar NPN medium-power switching applications.

Compared with MMBT4401 and ZTX653, FMMTL618TA uniquely balances 1.25 A current capability, 130 mV V_CE(sat), and SOT-23 manufacturability - making it optimal for high-volume, thermally constrained automotive and industrial SMT assemblies.

Availability

FMMTL618TA is available at Aetrix Electronics and suitable for automotive body control units, industrial relay drivers, DC-DC converter power stages, and LED current regulators requiring stable component supply across extended temperature ranges.

Supply support for FMMTL618TA 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

ON Semiconductor is a global semiconductor manufacturer specializing in energy-efficient power, analog, sensor, and connectivity solutions for automotive, industrial, and cloud power applications.

FMMTL618TA belongs to ON Semiconductor's general-purpose bipolar transistor product line, engineered for robust, cost-effective discrete switching and amplification in harsh-environment applications where reliability and thermal stability are critical.

FAQ

What is the maximum pulsed collector current for FMMTL618TA?

The absolute maximum pulsed collector current (I_CM) is 4 A, specified under pulsed conditions: pulse width ≤ 300 µs and duty cycle ≤ 2%. This rating applies only with adequate PCB copper thermal mass and ambient temperature ≤ 25°C; sustained operation above 1.25 A requires active derating per the SOA curve.

Does FMMTL618TA require a base resistor in switching applications?

Yes - a base resistor is mandatory to limit I_B and ensure proper saturation. For 1.25 A collector current, I_B ≥ 100 mA is required (h_FE ≥ 12.5 for forced β = 10). With a 3.3 V MCU GPIO, a 22 Ω resistor provides ~105 mA base drive, meeting saturation requirements without overdriving.

Is FMMTL618TA RoHS compliant and halogen-free?

Yes - FMMTL618TA is RoHS compliant (2011/65/EU) and halogen-free per ON Semiconductor's PPAP documentation. The SOT-23 package uses matte tin lead finish and meets JEDEC J-STD-020 moisture sensitivity level 1 (MSL-1), allowing unlimited floor life at ≤ 30°C/85% RH.

How does FMMTL618TA's gain vary with temperature?

h_FE increases with junction temperature: typical values are 200 at –55°C, 300 at +25°C, and 440 at +100°C (per datasheet Fig. 5). Designers must verify base drive sufficiency at minimum temperature (–55°C) and thermal runaway margin at maximum temperature (+150°C) in linear applications.