Analog Devices Inc./Maxim Integrated MAX1806EUA25

Overview

The MAX1806EUA25 from Maxim Integrated is a 2.5V fixed-output, 500mA low-dropout linear regulator featuring an internal PMOS pass transistor, ±1% output voltage accuracy over temperature and load, 175mV dropout at full load, and active-low power-OK (POK) monitoring - deployed in portable power rails for baseband processors in cellular handsets and USB-powered peripherals.

For engineers reviewing the MAX1806EUA25 datasheet, MAX1806EUA25 pinout, MAX1806EUA25 application, or MAX1806EUA25 equivalent, key selection criteria include guaranteed 500mA output under 175mV dropout, 0.02µA shutdown current, thermal overload protection at +170°C, and compatibility with 10µF low-ESR ceramic output capacitors for stable transient response.

Technical Context

The MAX1806EUA25 implements a P-channel MOSFET pass element with 0.4Ω R_DS(ON), eliminating base-drive current and enabling ultra-low 210µA ground current across load and temperature. Its dual-mode SET input supports either factory-trimmed 2.5V output (via GND connection) or adjustable operation (0.8V–4.5V) using external resistors.

Regulation relies on a precision 800mV internal reference and error amplifier comparing feedback from either internal divider (preset mode) or external SET node. The open-drain POK output asserts low when V_OUT falls below 93% of nominal (2.325V), with hysteresis ensured by internal comparator design.

Key Specifications

Pinout & Package

The MAX1806EUA25 is housed in an 8-pin Power-µMAX package with exposed thermal pad on the underside, requiring soldering to PCB ground plane for thermal performance up to 1.3W dissipation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS76325DBVR and MCP1702T-2502E/MB, the MAX1806EUA25 delivers 100% higher output current, 28% lower dropout at rated load, and 10× lower shutdown current - making it the optimal choice for space-constrained, high-efficiency 2.5V power rails demanding robust thermal and fault protection.

Availability

MAX1806EUA25 is available at Aetrix Electronics and suitable for cellular handset power management, USB peripheral regulation, portable medical instrumentation, docking station auxiliary supplies, and base station control logic requiring stable component supply with full traceability and long-term lifecycle support.

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) designs precision analog, mixed-signal, and power-management ICs for demanding industrial, communications, and consumer applications.

The MAX1806EUA25 belongs to Maxim's µMAX-packaged LDO family engineered for portable electronics requiring high current density, ultra-low quiescent current, and integrated power-good monitoring in minimal PCB area.

FAQ

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

The MAX1806EUA25 guarantees ±1% output voltage accuracy over the full operating temperature range (-40°C to +85°C) and load current range (1mA to 500mA), with VIN ≥ VOUT + 0.5V. This specification is confirmed in the Electrical Characteristics table under "Output Voltage Accuracy (Preset Mode)" and applies directly to the MAX1806EUA25's factory-trimmed 2.5V output.

Can the MAX1806EUA25 be used with ceramic output capacitors, and what ESR requirement must be met?

Yes, the MAX1806EUA25 is fully compatible with ceramic output capacitors. It requires a maximum ESR of 0.1Ω on the 10µF COUT capacitor to ensure stability and optimal transient response, as specified in the Applications Information section and validated in the "REGION OF STABLE COUT ESR vs. LOAD CURRENT" plot (Figure MAX1806 toc12). Surface-mount X5R/X7R ceramics meeting this ESR are recommended.

What is the function of the SET pin on the MAX1806EUA25, and how should it be configured for fixed 2.5V operation?

For fixed 2.5V operation, the SET pin of the MAX1806EUA25 must be connected directly to GND. This selects the internal feedback divider, activating the factory-trimmed 2.5V output. The SET pin's 800mV reference threshold and dual-mode comparator ensure precise regulation without external components - a configuration explicitly defined in the Selector Guide and Pin Description sections for the MAX1806EUA25 suffix.

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

During shutdown of the MAX1806EUA25, the POK output is actively held low regardless of the output voltage level. This behavior is documented in the Pin Description for SHDN and confirmed in the Detailed Description section: "When in shutdown, POK pulls low." It ensures unambiguous power-fail signaling to system controllers even when VOUT is decaying post-shutdown.

What thermal management provisions are required for the MAX1806EUA25 to sustain 500mA continuous output?

To sustain 500mA continuous output, the MAX1806EUA25 requires soldering of its exposed thermal pad to a large PCB ground plane or dedicated copper pour. The datasheet specifies 1.3W maximum power dissipation at TA = +70°C with 17mW/°C derating above that temperature - achievable only when the thermal pad is properly connected per the Package Information note and Figure 1 layout guidance.