Analog Devices Inc./Maxim Integrated MAX6349WLUT+

Overview

The MAX6349WLUT+ from Maxim Integrated is a 150mA low-dropout linear voltage regulator with integrated microprocessor reset circuit, preset to +1.8V output and -10% reset threshold (W suffix), housed in SOT23-6 package. It delivers ultra-low 25µA quiescent current, 180mV dropout at 100mA, and open-drain active-low RESET output - optimized for battery-powered portable electronics requiring reliable power sequencing and brownout protection.

For engineers reviewing the MAX6349WLUT+ datasheet, MAX6349WLUT+ pinout, MAX6349WLUT+ application, or MAX6349WLUT+ equivalent, key selection criteria include its fixed 1.8V output, -10% reset tolerance (VTH = 1.50V to 1.65V), manual reset input (MR), thermal/short-circuit protection, and compatibility with 1µF ceramic output capacitors in space-constrained designs.

Technical Context

The MAX6349WLUT+ integrates a P-channel MOSFET LDO regulator core and a precision reset supervisor sharing the same 1.23V internal reference. Its regulator operates from 2.5V to 5.5V input and maintains ±3.0% output accuracy over temperature and load. The reset circuit monitors VOUT continuously and asserts open-drain RESET for ≥100ms after recovery from under-voltage or MR activation.

Unlike the MAX6329, the MAX6349WLUT+ features a dedicated active-low manual reset input (MR) with 20kΩ internal pullup to OUT, 120ns glitch rejection, and 500ns MR-to-RESET delay - enabling external system-initiated resets without affecting regulation stability. It lacks shutdown control but includes reverse leakage protection and zero current flow from OUT to IN when VIN = 0V.

Key Specifications

Pinout & Package

Package: SOT23-6 - 6-pin surface-mount package with exposed thermal pad (GND pin functions as heatsink); footprint compatible with standard SOT-23 assembly processes and reflow profiles.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6329WLUT+, the MAX6349WLUT+ trades shutdown control for manual reset flexibility - critical for field-upgradeable or serviceable devices. Versus TPS76318QDBVRQ1, it offers tighter integration (reset + regulation in one SOT23-6 chip) and lower IQ, but lacks automotive qualification and higher dropout limits.

Availability

MAX6349WLUT+ is available at Aetrix Electronics and suitable for USB devices, cellular telephones, palm top computers, modems, and handheld instruments requiring stable component supply with long-term lifecycle support.

Supply support for MAX6349WLUT+ 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 and mixed-signal ICs for power management, sensing, and interface applications.

The MAX6329/MAX6349 product line targets battery-powered portable equipment needing micropower regulation and reliable power-on reset - emphasizing small size, low IQ, and integrated supervision to reduce external component count.

FAQ

What output voltage does the MAX6349WLUT+ provide, and how is it set?

The MAX6349WLUT+ provides a fixed +1.8V output, confirmed by its "W" suffix in the ordering code. This is achieved by connecting the SET pin to GND, which selects the internal resistor divider for 1.8V regulation. The device maintains ±3.0% accuracy across temperature and load. No external resistors are needed for this configuration, simplifying layout and reducing BOM cost compared to adjustable variants.

Does the MAX6349WLUT+ include a manual reset function, and how is it implemented?

Yes, the MAX6349WLUT+ includes a dedicated manual reset (MR) input on Pin 3. It is an active-low input with a 20kΩ internal pullup to OUT, allowing direct connection to a momentary switch (to GND) or logic signal. When asserted, MR forces the open-drain RESET output low for ≥100ms after release. This feature is exclusive to MAX6349 variants and is not present in the MAX6329 family.

What is the reset threshold and timeout behavior of the MAX6349WLUT+?

The MAX6349WLUT+ uses a -10% reset threshold relative to its 1.8V output, resulting in VTH = 1.50V to 1.65V. RESET remains asserted while VOUT is below this threshold and continues for a minimum of 100ms after VOUT rises above it. This timeout ensures stable power and clock conditions before releasing the microprocessor, eliminating need for external timing components.

Can the MAX6349WLUT+ operate with a 1µF output capacitor, and what type is recommended?

Yes, the MAX6349WLUT+ is fully stable with a minimum 1µF ceramic output capacitor. X7R or X5R dielectrics are recommended for consistent performance across -40°C to +85°C; Z5U or Y5V types may require ≥2.2µF for low-temperature stability. A 1µF IN-to-GND capacitor is also advised to improve PSRR and transient response, per the datasheet's Typical Operating Circuit.

How does reverse leakage protection work in the MAX6349WLUT+?

The MAX6349WLUT+ incorporates reverse leakage protection that disables the internal pass transistor when VOUT > VIN, preventing current flow from OUT to IN. This eliminates the need for external blocking diodes in backup-battery or dual-supply configurations. Measured reverse leakage is effectively zero - less than 0.01µA - ensuring no parasitic discharge of auxiliary power sources.