Analog Devices Inc./Maxim Integrated MAX6363LUT31+

Overview

MAX6363LUT31+ from Maxim Integrated is a low-power microprocessor supervisory circuit with battery switchover and BATT ON status indication, designed for systems requiring reliable power monitoring and SRAM backup during brownout. It operates from +1.2V supply, features a factory-preset 3.08V reset threshold (±1.5% over temperature), 150ms minimum reset timeout, and delivers up to 150mA from VCC or battery via the OUT pin in backup mode.

For engineers reviewing the MAX6363LUT31+ datasheet, MAX6363LUT31+ pinout, MAX6363LUT31+ application, or MAX6363LUT31+ equivalent, key selection criteria include its active-low push-pull RESET output, guaranteed reset assertion down to 1.2V supply, battery-on indicator functionality, and SOT23-6 package compatibility with space-constrained portable and industrial control designs.

Technical Context

The MAX6363LUT31+ integrates precision voltage monitoring, automatic battery switchover logic, and a dedicated BATT ON output that asserts high only when VCC falls below both the 3.08V reset threshold and VBATT (with 40mV hysteresis). Its internal MOSFET switch connects the backup battery to OUT when VCC drops, with on-resistance as low as 2.38Ω at VBATT = 2.0V and 25mA load.

Unlike the MAX6361 (manual reset) or MAX6362 (watchdog), the MAX6363 variant omits MR and WDI inputs, dedicating pins to BATT ON and fixed-threshold supervision. Its RESET output is push-pull active-low, eliminating external pull-up requirements and ensuring fast, rail-to-rail reset signaling compatible with TTL/CMOS µP reset inputs.

Key Specifications

Pinout & Package

Package: 6-pin SOT23 (U6-1 outline, 2.1mm × 1.6mm footprint), RoHS-compliant, -40°C to +85°C operating range.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar microprocessor supervisory applications.

Compared with MAX6363HUT31+, the MAX6363LUT31+ offers identical functionality at lower cost for commercial-temperature applications, while the TPS3808G33DBVR provides a simpler, lower-cost reset-only solution lacking battery-handling features required for SRAM retention.

Availability

MAX6363LUT31+ is available at Aetrix Electronics and suitable for portable medical monitors, industrial PLC I/O modules, smart energy meters, and ruggedized handheld testers requiring stable component supply with guaranteed long-term availability.

Supply support for MAX6363LUT31+ 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 in industrial, medical, and communications systems.

The MAX6361–MAX6364 family was developed specifically for microprocessor-based systems needing integrated power supervision, battery switchover, and compact packaging-targeting space- and power-constrained portable and industrial equipment.

FAQ

What is the exact reset threshold voltage of the MAX6363LUT31+ and how tightly is it specified?

The MAX6363LUT31+ has a factory-trimmed reset threshold of 3.08V, with guaranteed limits of 3.00V (minimum) and 3.15V (maximum) over the full -40°C to +85°C temperature range. This ±1.5% tolerance ensures robust detection of 3.3V supply droop without false triggering during normal ripple or transient conditions. The MAX6363LUT31+ achieves this accuracy using laser-trimmed on-chip resistors and a precision bandgap reference.

Does the MAX6363LUT31+ require an external pull-up resistor on its RESET pin?

No, the MAX6363LUT31+ features an active-low push-pull RESET output, meaning it actively drives both high and low states without requiring an external pull-up resistor. This simplifies PCB layout, reduces component count, and ensures fast, rail-to-rail reset transitions compatible with standard µP reset inputs. The MAX6363LUT31+ can sink up to 20mA and source 500µA on the RESET pin.

How does the battery switchover function work in the MAX6363LUT31+ and what is the hysteresis value?

The MAX6363LUT31+ automatically switches the OUT pin from VCC to the BATT source when VCC falls below both the 3.08V reset threshold and VBATT minus 20mV. Switchover back to VCC occurs when VCC rises 20mV above VBATT, resulting in a total 40mV hysteresis. This prevents oscillation during slow VCC decay. The MAX6363LUT31+ uses an internal MOSFET with on-resistance as low as 2.38Ω to minimize voltage drop in backup mode.

Can the MAX6363LUT31+ operate with a 1.8V main supply voltage?

Yes, the MAX6363LUT31+ operates from VCC as low as +1.2V, making it fully compatible with 1.8V systems. Its RESET output remains asserted (low) down to 1.2V, and the internal voltage reference and comparator continue functioning accurately. However, the 3.08V reset threshold means it will assert reset when a 1.8V supply drops below that level-so it is typically used with ≥3.0V supplies or as a secondary monitor in multi-rail systems. The MAX6363LUT31+ draws only 10µA at 1.8V, preserving battery life.

What is the purpose of the BATT ON pin on the MAX6363LUT31+ and how is it used in system design?

The BATT ON pin on the MAX6363LUT31+ is an open-drain output that goes high (pulled up externally) only when the device is actively supplying power from the backup battery to the OUT pin-i.e., during valid battery-backup mode. System firmware uses this signal to trigger data save operations, disable non-essential peripherals, or log power-failure events. Unlike generic power-good flags, BATT ON is synchronized precisely with the switchover event, providing deterministic timing for critical actions. The MAX6363LUT31+ guarantees BATT ON assertion within 1µs of switchover initiation.