Analog Devices Inc./Maxim Integrated MAX1818EUT25-T

Overview

The MAX1818EUT25-T from Maxim Integrated is a 2.5V fixed-output, 500mA low-dropout linear regulator featuring ±1% output voltage accuracy, 120mV dropout at full load, and 125μA ground current independent of load. It integrates an active-low open-drain POK (power-ok) output, 0.1μA shutdown current, and thermal/short-circuit protection. Designed for portable battery-powered systems, it powers core logic rails in notebook computers and USB hubs where stable low-voltage regulation and minimal quiescent consumption are critical.

For engineers reviewing the MAX1818EUT25-T datasheet, MAX1818EUT25-T pinout, MAX1818EUT25-T application, or MAX1818EUT25-T equivalent, this page delivers verified technical context-including Dual Mode™ voltage selection, SOT23-6 thermal derating limits, POK threshold at 93% VOUT, and guaranteed 500mA RMS output under 2.5V–5.5V input-enabling accurate power-rail design and BOM validation.

Technical Context

The MAX1818EUT25-T employs an internal P-channel MOSFET pass transistor with 0.25Ω RDS(ON), enabling low dropout and eliminating base-drive current draw. Its error amplifier compares a 1.25V reference against feedback from either internal resistors (for 2.5V preset) or an external SET-divider, with Dual Mode™ comparator selecting path based on SET voltage (<50mV → preset mode).

Protection circuitry includes foldback current limiting (0.55–1.8A short-circuit limit), thermal shutdown at +170°C with 20°C hysteresis, and POK output asserting low when VOUT falls below 93% of nominal 2.5V. Ground current remains ≤140μA across 1mA–500mA load and -40°C to +85°C ambient.

Key Specifications

Pinout & Package

Package: 6-pin SOT23-6 (U6F-6 outline), 800mW power dissipation at TA = +70°C, derated 10mW/°C above +70°C. Requires IPC-JEDEC J-STD-020A reflow profile; hand/wave soldering prohibited.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar low-dropout linear regulator applications.

Compared with the MAX1818EUT25-T, the TPS76325QDBVRQ1 trades 500mA capability for automotive qualification and wider temperature range, while the MCP1825-2502E/DB matches output current but lacks POK signaling and suffers 130mV higher dropout-reducing battery runtime in portable systems.

Availability

MAX1818EUT25-T is available at Aetrix Electronics and suitable for notebook computers, USB hubs, cellular telephones, and base stations requiring stable component supply, RoHS compliance, and guaranteed -40°C to +85°C operation.

Supply support for MAX1818EUT25-T 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

Maxim Integrated (now part of Analog Devices) designs precision analog, mixed-signal, and power-management ICs for demanding industrial, communications, and consumer applications.

The MAX1818 series targets portable battery-operated equipment, delivering high-current LDO regulation with ultra-low quiescent current, integrated power monitoring, and robust thermal protection in miniature SOT23 packages.

FAQ

What is the guaranteed output voltage accuracy of the MAX1818EUT25-T over temperature and load?

The MAX1818EUT25-T guarantees ±3% output voltage accuracy across the full operating range of -40°C to +85°C and 1mA to 500mA load current. At +25°C and 100mA load, accuracy tightens to ±1%. This specification ensures reliable 2.5V rail generation for logic interfaces even under worst-case thermal and loading conditions, directly supporting system-level timing margin calculations.

Does the MAX1818EUT25-T require external components for stable operation?

Yes, the MAX1818EUT25-T requires a 1µF ceramic capacitor between IN and GND, and a 3.3µF low-ESR (<0.1Ω) ceramic capacitor between OUT and GND. These capacitors ensure loop stability, suppress input noise, and maintain transient response within spec. For 2.5V output, the 3.3µF value is mandatory; using smaller values risks oscillation or excessive output ripple.

How does the POK output function on the MAX1818EUT25-T, and what external component is needed?

The POK output on the MAX1818EUT25-T is an open-drain N-channel driver that pulls low when VOUT drops below 93% of nominal (2.325V). To generate a logic-high signal when regulation is valid, a 100kΩ pull-up resistor must connect POK to OUT. This configuration provides a rail-referenced power-good signal compatible with most microcontroller reset inputs without level-shifting.

What thermal limitations apply to the MAX1818EUT25-T in a standard SOT23-6 layout?

In a standard SOT23-6 layout with one square-inch of copper on the PCB, the MAX1818EUT25-T dissipates up to 800mW at +70°C ambient, derating 10mW/°C above that. With minimal copper, power handling drops to 712mW. Thermal performance depends critically on equal copper distribution among IN, OUT, and GND pins-uneven layout causes localized heating and premature thermal shutdown.

Can the MAX1818EUT25-T be used in adjustable-output configurations?

No-the MAX1818EUT25-T is factory-trimmed for fixed 2.5V output and does not support adjustable operation. While the underlying MAX1818 family features Dual Mode™, the "25" suffix in MAX1818EUT25-T explicitly denotes the 2.5V preset variant. Attempting to bias the SET pin for adjustment will result in undefined regulation behavior and potential instability.