Analog Devices Inc./Maxim Integrated MAX1806EUA25+

Overview

MAX1806EUA25+ from Maxim Integrated is a 2.5V fixed-output, 500mA low-dropout linear regulator featuring ±1% output voltage accuracy, 175mV dropout at full load, and 210μA ground current. It uses an internal PMOS pass transistor and delivers stable power to core logic rails in portable and space-constrained systems including USB hubs, docking stations, and cellular handsets.

For engineers reviewing the MAX1806EUA25+ datasheet, MAX1806EUA25+ pinout, MAX1806EUA25+ application, or MAX1806EUA25+ equivalent, key selection criteria include guaranteed 500mA output under 175mV dropout, active-low POK monitoring, 0.02μA shutdown current, thermal overload protection, and compatibility with 1μF/10μF ceramic input/output capacitors.

Technical Context

The MAX1806EUA25+ implements a dual-mode feedback architecture: when SET is grounded, it regulates to factory-trimmed 2.5V using an internal resistive divider; when external resistors are connected to SET, it adjusts output from 0.8V to 4.5V via 800mV reference threshold. Its P-channel MOSFET pass device eliminates base-drive current, enabling ultra-low quiescent operation.

It integrates a thermal shutdown circuit (trip at +170°C, 20°C hysteresis), short-circuit current limiting (700–2500mA), and open-drain POK output that asserts low when VOUT falls below 93% of nominal. Input undervoltage lockout activates at 1.85–2.15V with 40mV hysteresis, ensuring clean startup from weak or decaying supplies.

Key Specifications

Pinout & Package

The MAX1806EUA25+ is housed in an 8-pin Power-μMAX package (3mm × 3mm, 0.8mm height) with an exposed thermal pad on the underside. The pad must be soldered to a large copper area or ground plane to achieve rated 1.3W power dissipation and thermal performance.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS76325DBVR and MCP1825-2502E/DB, the MAX1806EUA25+ uniquely combines 500mA capability, 175mV dropout, integrated POK, and thermal hysteresis in a thermally enhanced μMAX package - making it optimal for space-constrained, high-reliability portable power rails.

Availability

MAX1806EUA25+ is available at Aetrix Electronics and suitable for USB hubs, cellular phone baseband supplies, and docking station peripheral rails requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for MAX1806EUA25+ 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) is a U.S.-based semiconductor company specializing in high-performance analog, mixed-signal, and power management ICs for industrial, communications, and consumer applications.

The MAX1806 series was designed specifically for portable equipment requiring ultra-low quiescent current, precise low-voltage regulation, and robust fault protection - targeting PDAs, cellular handsets, and compact docking solutions.

FAQ

What is the guaranteed output voltage tolerance for MAX1806EUA25+ across temperature and load?

The MAX1806EUA25+ guarantees ±1% output voltage accuracy at TA = +85°C and IOUT = 100mA. Over the full operating range (-40°C to +85°C, 1mA–500mA load, VIN > VOUT + 0.5V), output voltage remains within ±3% of 2.5V. This specification is confirmed in the Electrical Characteristics table under "Output Voltage Accuracy (Preset Mode)" and applies directly to the MAX1806EUA25+ variant.

Does MAX1806EUA25+ require external components to operate, and if so, what are the minimum requirements?

Yes, the MAX1806EUA25+ requires two mandatory external capacitors: a 1μF ceramic capacitor between IN and GND, and a 10μF low-ESR (<0.1Ω) ceramic capacitor between OUT and GND. A 100kΩ pullup resistor from POK to OUT is required for functional power-good signaling. These values are specified in the Typical Operating Circuit and Applications Information sections of the MAX1806EUA25+ datasheet.

Can MAX1806EUA25+ be used in adjustable-output configurations, or is it strictly fixed at 2.5V?

The MAX1806EUA25+ is factory-trimmed for 2.5V output and intended for fixed-voltage use. While the underlying MAX1806 architecture supports adjustable mode via the SET pin, the MAX1806EUA25+ variant is characterized and tested only in preset mode. Using external resistors on SET may yield unpredictable accuracy or stability - Maxim does not specify or guarantee performance in adjustable mode for this specific suffix.

What thermal derating applies to MAX1806EUA25+ at ambient temperatures above +70°C?

The MAX1806EUA25+ has a continuous power dissipation limit of 1.3W at TA = +70°C. Above +70°C, power dissipation must be linearly derated at 17mW/°C. For example, at TA = +85°C, maximum allowable power drops to 1.3W − (15°C × 17mW/°C) = 1.045W. This derating assumes proper thermal pad soldering to PCB ground plane per the Package Information section.

How does the POK output of MAX1806EUA25+ behave during shutdown?

During shutdown (SHDN = GND), the POK output of MAX1806EUA25+ is actively held low regardless of the output voltage level. This behavior is explicitly stated in the Detailed Description section: "When in shutdown, POK is held low independent of the output voltage." It ensures deterministic system-level power sequencing - the host MCU receives a known state on the POK line during both fault and intentional shutdown conditions.