Analog Devices Inc./Maxim Integrated MAX1806EUA18+

Overview

MAX1806EUA18+ from Maxim Integrated is a 500mA, low-dropout linear regulator with fixed 1.8V output, ±1% accuracy over -40°C to +85°C, 175mV dropout at full load, and 210μA ground current - designed for power rail regulation in portable battery-powered systems including PDAs, cellular handsets, and USB hubs.

For engineers reviewing the MAX1806EUA18+ datasheet, MAX1806EUA18+ pinout, MAX1806EUA18+ application, or MAX1806EUA18+ equivalent, key selection criteria include guaranteed 500mA output under 175mV dropout, active-low POK monitoring, 0.02μA shutdown current, thermal/short-circuit protection, and compatibility with 1μF input / 10μF low-ESR output capacitors.

Technical Context

The MAX1806EUA18+ uses an internal PMOS pass transistor with ~0.4Ω R_DS(ON), enabling low dropout and eliminating base-drive current loss typical of PNP regulators. Its dual-mode feedback architecture selects between factory-trimmed 1.8V output (via SET = GND) and adjustable mode (via external resistor divider), with 800mV reference voltage at the SET pin.

Protection logic integrates thermal shutdown at +170°C (20°C hysteresis), short-circuit current limiting (700–2500mA), and undervoltage lockout (1.85–2.15V). The open-drain POK output asserts low when V_OUT falls below 93% of nominal, requiring a 100kΩ pullup to OUT for logic-level signaling.

Key Specifications

Pinout & Package

MAX1806EUA18+ is housed in an 8-pin Power-μMAX package (1.3W thermal rating) with an exposed metal thermal pad on the underside for PCB heat sinking. Both IN pins (1,2) and OUT pins (7,8) must be connected externally in parallel.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS7A2018PDQNR and MCP1826T-1802E/DB, the MAX1806EUA18+ uniquely combines POK monitoring, thermal self-recovery, and ultra-low shutdown current in a miniature Power-μMAX package - making it optimal for portable systems requiring robust power sequencing and extended battery life.

Availability

MAX1806EUA18+ is available at Aetrix Electronics and suitable for cellular handset power rails, USB hub I/O supplies, industrial sensor node MCUs, base station FPGA configuration, and portable docking station designs requiring stable component supply with full traceability and long-term lifecycle support.

Supply support for MAX1806EUA18+ 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 semiconductor company specializing in high-performance analog, mixed-signal, and power management ICs for industrial, communications, and consumer applications.

The MAX1806 belongs to Maxim's μMAX low-dropout regulator family, engineered for portable electronics requiring high output accuracy, ultra-low quiescent current, and integrated fault protection in space-constrained packages.

FAQ

What is the guaranteed output voltage tolerance for MAX1806EUA18+ across temperature and load?

The MAX1806EUA18+ guarantees ±1% output voltage accuracy over -40°C to +85°C and 1mA to 500mA load current when VIN > VOUT + 0.5V. At +85°C and 100mA load, the tolerance tightens to ±1%. This precision ensures reliable operation of sensitive 1.8V logic without external trimming or calibration - critical for consistent performance in handheld and industrial devices using MAX1806EUA18+.

Can MAX1806EUA18+ operate from a 2.5V input while delivering 500mA at 1.8V?

Yes - with a 2.5V input, MAX1806EUA18+ maintains regulation at 500mA because its maximum dropout is 175mV (2.5V − 1.8V = 700mV margin). The device remains well within specification, with typical dropout dropping to ~147mV at VOUT = 1.8V per characterization data. This headroom ensures stable 1.8V output even under worst-case process/voltage/temperature conditions for MAX1806EUA18+.

How is the POK output used in system power sequencing with MAX1806EUA18+?

The POK pin on MAX1806EUA18+ is an open-drain output that pulls low when VOUT falls below 93% of 1.8V (i.e., <1.674V) and goes high-impedance when regulation is achieved. It requires a 100kΩ pullup to OUT to generate a logic-high signal. This allows MAX1806EUA18+ to directly enable downstream regulators or assert reset to a microcontroller only after stable 1.8V is established - simplifying sequencing in compact portable designs.

What PCB layout requirements are essential for thermal performance of MAX1806EUA18+?

MAX1806EUA18+ requires soldering its exposed thermal pad (underside of Power-μMAX package) to a large copper area or internal ground plane using ≥4 thermal vias. Failure to do so limits continuous 500mA operation above +70°C ambient due to insufficient heat dissipation. The datasheet specifies 1.3W max power dissipation at TA = +70°C, derating 17mW/°C above - achievable only with proper thermal pad implementation for MAX1806EUA18+.

Does MAX1806EUA18+ support adjustable output voltage, or is it fixed-only?

MAX1806EUA18+ is factory-trimmed for fixed 1.8V output, but retains full adjustable-mode capability via the SET pin. Connecting an external resistor divider from OUT to SET allows output adjustment from 0.8V to 4.5V using the formula R1 = R2 × ((VOUT / 0.8V) − 1). This flexibility lets designers reuse the same MAX1806EUA18+ footprint for multiple voltage rails - a key advantage over strictly fixed-output alternatives.