Diodes Incorporated FMMTL618TC

Overview

FMMTL618TC 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 operates across –55°C to +150°C, used in DC-DC converter power switches and load driver stages.

For engineers reviewing the FMMTL618TC datasheet, FMMTL618TC pinout, FMMTL618TC application, or FMMTL618TC equivalent, key selection criteria include verified V_CE(sat) performance at 1.25 A, h_FE stability across temperature, SOT-23 thermal derating behavior, and complementary pairing with FMMTL718 for push-pull output stages.

Technical Context

This NPN transistor uses a planar epitaxial structure optimized for medium-current switching with controlled saturation voltage and gain linearity. Its f_T = 195 MHz at I_C = 50 mA / V_CE = 10 V supports fast turn-on/turn-off (t_on = 72 ns, t_off = 388 ns) under pulsed conditions (300 µs, ≤2% duty cycle).

The device meets absolute maximum ratings including V_CBO = 60 V, V_EBO = 5 V, P_tot = 500 mW at T_amb = 25°C, and safe operating area validated up to I_C = 10 A with V_CE ≤ 2 V at T_j = 25°C. C_obo = 9–12 pF enables predictable high-frequency response in driver circuits.

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 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, FMMTL618TC uniquely balances 1.25 A current handling, 130 mV saturation, SOT-23 manufacturability, and –55°C to +150°C operation-making it optimal for thermally constrained, high-reliability medium-power switching where both performance and assembly scalability matter.

Availability

FMMTL618TC is available at Aetrix Electronics and suitable for DC-DC converters, motor drivers, LED current sinks, and industrial sensor interfaces requiring stable component supply across automotive, industrial, and embedded power systems.

Supply support for FMMTL618TC 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 power management, analog, sensors, and connectivity solutions for automotive, industrial, and cloud power applications.

FMMTL618TC belongs to ON Semiconductor's general-purpose bipolar transistor product line, engineered for cost-effective, thermally robust switching and amplification in space-constrained, medium-current applications.

FAQ

What is the maximum allowable base current for continuous operation?

The absolute maximum base current is 200 mA per the datasheet's Absolute Maximum Ratings table. For reliable long-term operation, base current should be limited to ≤100 mA under continuous DC conditions to prevent bond wire overheating and ensure h_FE stability. Pulse operation allows up to 200 mA with ≤2% duty cycle and 300 µs pulse width.

Can FMMTL618TC replace a MOSFET in low-side switching applications?

Yes, but with trade-offs: it offers lower gate drive complexity (no gate charge, no level-shifting) and better SOA at high V_CE, but higher conduction loss than modern MOSFETs due to V_CE(sat) vs. R_DS(on). Use when simplicity, cost, or ruggedness outweigh efficiency demands-especially below 100 kHz switching and ≤2 A loads.

Is the SOT-23 package lead-free and RoHS compliant?

Yes, FMMTL618TC is manufactured in a lead-free, RoHS-compliant SOT-23 package per ON Semiconductor's packaging standards. The device meets JEDEC J-STD-020 moisture sensitivity level (MSL) 1 and supports standard reflow profiles including peak temperatures up to 260°C.

How does h_FE vary with temperature and collector current?

h_FE increases with temperature: typical values rise from ~200 at –55°C to ~440 at +100°C for I_C = 10 mA. At I_C = 1.25 A, h_FE drops to ~100–190, reflecting gain compression at high current density. Designers must verify base drive sufficiency across the full operating temperature and current range.