Analog Devices Inc./Maxim Integrated MAX1806EUA18+T

Overview

MAX1806EUA18+T from Maxim Integrated is a 500mA, low-dropout linear regulator with fixed 1.8V output, ±1% accuracy, 175mV dropout at full load, and 210μA ground current. It features an active-low power-OK (POK) output, 0.02μA shutdown current, thermal shutdown, and short-circuit protection. Designed for space-constrained portable systems, it powers core logic rails in PDAs, cellular handsets, and USB hubs.

For engineers reviewing the MAX1806EUA18+T datasheet, MAX1806EUA18+T pinout, MAX1806EUA18+T application, or MAX1806EUA18+T equivalent, key selection criteria include guaranteed 500mA output under 175mV dropout, preset 1.8V output with ±1% tolerance over -40°C to +85°C, POK monitoring capability, and compatibility with 1μF input / 10μF low-ESR output capacitors.

Technical Context

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

Power-OK functionality monitors V_OUT against 93% of nominal regulation voltage using an open-drain N-channel output requiring external pull-up; thermal protection activates at +170°C with 20°C hysteresis, and shutdown reduces supply current to 0.02μA while forcing POK low.

Key Specifications

Pinout & Package

The MAX1806EUA18+T is housed in an 8-pin Power-μMAX package (1.3W rating) with an exposed metal thermal pad on the underside, requiring soldering to PCB ground plane for thermal performance.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS7A2018PDBVR and MCP1826-1802E/DB, the MAX1806EUA18+T uniquely combines 500mA capability, 175mV dropout, integrated POK, and 0.02μA shutdown in a thermally enhanced μMAX package - making it optimal for portable systems demanding both performance and supervisory functionality.

Availability

MAX1806EUA18+T is available at Aetrix Electronics and suitable for notebook computers, cellular telephones, and USB hubs requiring stable component supply, long-term lifecycle assurance, and RoHS-compliant packaging.

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

The MAX1806 series belongs to Maxim's precision low-dropout regulator product line, engineered for portable electronics requiring tight voltage accuracy, ultra-low quiescent current, and robust fault protection in miniature packages.

FAQ

What is the guaranteed output voltage accuracy of the MAX1806EUA18+T over temperature and load?

The MAX1806EUA18+T guarantees ±1% output voltage accuracy at +85°C and 100mA load, ±1.5% at +85°C across 1mA–500mA, and ±3% over the full -40°C to +85°C range with 1mA–500mA load and VIN > VOUT + 0.5V. This ensures reliable 1.8V rail stability for sensitive digital logic without external trimming. The MAX1806EUA18+T achieves this via factory-trimmed internal resistive divider and precision 0.8V reference.

Does the MAX1806EUA18+T require external components for stable operation?

Yes - the MAX1806EUA18+T requires a 1μF ceramic capacitor from IN to GND and a 10μF low-ESR (≤0.1Ω) capacitor from OUT to GND, placed as close as possible to the device. These capacitors ensure loop stability, minimize output noise, and improve load-transient response. The MAX1806EUA18+T datasheet specifies that ESR outside 0.01–0.1Ω may cause instability or excessive overshoot.

How does the POK (Power-OK) output function on the MAX1806EUA18+T?

The POK pin on the MAX1806EUA18+T is an open-drain N-channel output that pulls low when VOUT falls below 93% of its nominal 1.8V value (i.e., <1.674V). It goes high-impedance once VOUT exceeds that threshold. A 100kΩ pull-up resistor to OUT is required to generate a logic-high signal. During shutdown, POK is forced low regardless of VOUT - a behavior explicitly defined in the MAX1806EUA18+T functional description.

What thermal management considerations apply to the MAX1806EUA18+T?

The MAX1806EUA18+T uses an exposed thermal pad on the underside of its Power-μMAX package, which must be soldered to a large PCB copper area or ground plane to achieve rated 1.3W power dissipation. Without proper thermal connection, junction temperature can exceed +150°C under 500mA load with >1V input-output differential. The MAX1806EUA18+T includes thermal shutdown at +170°C with 20°C hysteresis, but continuous operation above TJ = +150°C is prohibited per absolute maximum ratings.

Can the MAX1806EUA18+T be used in adjustable-output configurations?

No - the MAX1806EUA18+T is factory-configured for fixed 1.8V output and cannot be adjusted. While the MAX1806 family supports adjustable mode via the SET pin, the "EUA18+" suffix denotes the preset 1.8V variant with internal feedback divider. Attempting to connect external resistors to SET will not alter the output, as the dual-mode comparator locks to internal trim when SET voltage remains below 35mV - the condition met when SET is grounded, as specified for this variant. The MAX1806EUA18+T is not pin-compatible with adjustable versions like MAX1806EUA+.