Analog Devices Inc./Maxim Integrated MAX1818EUT33-T

Overview

The MAX1818EUT33-T from Maxim Integrated is a 3.3V 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 space-constrained portable systems, it powers core logic rails in notebook computers and USB hubs.

For engineers reviewing the MAX1818EUT33-T datasheet, MAX1818EUT33-T pinout, MAX1818EUT33-T application, or MAX1818EUT33-T equivalent, key selection criteria include guaranteed 500mA output under 120mV dropout, preset 3.3V operation without external resistors, SOT23-6 footprint compatibility, and POK signaling for microcontroller power sequencing.

Technical Context

The MAX1818EUT33-T employs an internal P-channel MOSFET pass transistor with 0.25Ω R_DS(ON), enabling low dropout and eliminating base-drive current draw. Its Dual Mode™ architecture selects factory-trimmed 3.3V regulation when the SET pin is grounded-no external feedback required.

Regulation relies on a 1.25V internal reference and error amplifier comparing feedback from either internal resistive dividers (for preset mode) or external resistors (adjustable mode). The POK output asserts low when V_OUT falls below 93% of nominal 3.3V and operates as an open-drain signal requiring external pull-up.

Key Specifications

Pinout & Package

MAX1818EUT33-T is housed in a RoHS-compliant 6-pin SOT23-6 package (U6FH-6 outline), rated for 800mW power dissipation at +70°C with standard PCB copper layout.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar LDO regulator applications.

Compared with MAX1818EUT33-T, the XC6219B332MR-G saves board area but forfeits power-good signaling, while the AP2112K-3.3TRG1 delivers more current at the cost of reduced efficiency and no rail-monitoring capability-making MAX1818EUT33-T optimal for systems requiring both precision regulation and hardware power sequencing.

Availability

MAX1818EUT33-T is available at Aetrix Electronics and suitable for notebook computers, USB hubs, and cellular telephones requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for MAX1818EUT33-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, automotive, and portable applications.

The MAX1818 series targets battery-powered equipment needing ultra-low quiescent current, low dropout, and integrated power monitoring-specifically addressing voltage regulation challenges in PDAs, smartphones, and compact computing platforms.

FAQ

What is the guaranteed dropout voltage of the MAX1818EUT33-T at 500mA load?

The MAX1818EUT33-T guarantees a maximum dropout voltage of 215mV at 500mA load and 3.3V output, with typical performance at 120mV. This specification is measured per JEDEC definition: VIN – VOUT when VOUT drops 100mV below its nominal value under specified conditions. The low dropout enables operation from partially discharged batteries in portable devices.

Does the MAX1818EUT33-T require external resistors to set its 3.3V output?

No, the MAX1818EUT33-T does not require external resistors for 3.3V operation. Its "EUT33" suffix indicates factory-trimmed internal feedback, so grounding the SET pin directly configures the device for fixed 3.3V output. External resistors are only needed if adjusting output voltage outside the preset values.

How does the POK output function on the MAX1818EUT33-T?

The POK output on the MAX1818EUT33-T is an open-drain N-channel signal that pulls low when VOUT falls below 93% of nominal 3.3V (i.e., 3.069V). It goes high-impedance when regulation is restored. To use it as a logic signal, connect a 100kΩ pull-up resistor from POK to OUT. During shutdown, POK is forcibly held low regardless of output voltage.

What thermal protection features does the MAX1818EUT33-T include?

The MAX1818EUT33-T incorporates thermal shutdown at +170°C junction temperature with +20°C hysteresis. When triggered, the pass transistor turns off completely, allowing the die to cool before automatic recovery. This protects against permanent damage during sustained overload or poor heatsinking, complementing its 800mW power dissipation rating at +70°C ambient.

Can the MAX1818EUT33-T be used with ceramic output capacitors?

Yes, the MAX1818EUT33-T is fully compatible with ceramic output capacitors. It requires a minimum 3.3μF low-ESR capacitor (≤0.1Ω) at the OUT pin for stability and optimal transient response. Surface-mount X5R/X7R ceramics meeting this ESR spec are recommended and widely available up to 10μF, simplifying layout and reducing solution size.