Analog Devices Inc./Maxim Integrated MAX6831SZUT+

Overview

MAX6831SZUT+ from Maxim Integrated is an ultra-low-voltage dual-supply microprocessor supervisory IC with open-drain active-low RESET output, factory-trimmed VCC2 monitor (2.5V threshold), manual reset input, and 1.6s watchdog timer. It monitors primary supply VCC (1.8V–5.0V) and secondary supply VCC2 (0.9V–2.5V), asserts reset if either falls below threshold, and maintains reset for ≥140ms after recovery. It is used in battery-powered embedded systems requiring reliable power-on reset and brownout protection.

For engineers reviewing the MAX6831SZUT+ datasheet, MAX6831SZUT+ pinout, MAX6831SZUT+ application, or MAX6831SZUT+ equivalent, key selection considerations include its open-drain RESET output compatibility with bidirectional µP reset pins, guaranteed reset validity down to VCC = +1.0V, immunity to short negative VCC transients, and factory-set 2.5V VCC2 threshold with no external components required.

Technical Context

The MAX6831SZUT+ integrates two independent voltage monitors: a programmable primary VCC threshold (selected by suffix 'S' = 2.93V) and a fixed secondary VCC2 monitor (2.5V nominal). Its internal 1.6s watchdog timer clears on any WDI edge and triggers reset if unattended beyond timeout.

It features an open-drain RESET output compatible with bidirectional microcontroller reset I/O (e.g., Motorola 68HC11), internal 50kΩ MR pullup, and high-impedance VCC2 input with guaranteed operation down to VCC = +1.0V - enabling robust reset assertion during deep brownout conditions without external support circuitry.

Key Specifications

Pinout & Package

MAX6831SZUT+ is housed in a RoHS-compliant 6-pin SOT23 package (package code U6+1, outline 21-0058), footprint-compatible with industry-standard 6-lead SOT-23 layouts.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual-supply supervisory applications.

Compared with MAX6830SZUT+, the MAX6831SZUT+ provides open-drain flexibility for reset bus sharing and bidirectional µP interfaces, while TPS3808G33DBVR lacks VCC2 monitoring and watchdog - making it unsuitable as a drop-in replacement but viable for simplified single-rail designs.

Availability

MAX6831SZUT+ is available at Aetrix Electronics and suitable for portable/battery-powered equipment, embedded controllers, and intelligent instruments requiring stable component supply across extended temperature ranges (-40°C to +125°C) and long production lifecycles.

Supply support for MAX6831SZUT+ 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, medical, and communications applications.

The MAX6826–MAX6831 family delivers ultra-low-voltage dual-supply supervision with integrated watchdog and manual reset - engineered specifically for space-constrained, battery-operated embedded systems needing high reliability under brownout conditions.

FAQ

What is the exact VCC2 reset threshold voltage for MAX6831SZUT+?

The MAX6831SZUT+ has a factory-trimmed VCC2 reset threshold of 2.5V, with a tolerance of ±7mV over the full operating temperature range (-40°C to +125°C). This value is specified in the Electrical Characteristics table under "VCC2 Reset Threshold" for suffix 'Z', and applies exclusively to the MAX6829/MAX6830/MAX6831 variants. The MAX6831SZUT+ uses this fixed 2.5V threshold without requiring external resistors or calibration.

Does MAX6831SZUT+ support bidirectional microcontroller reset pins?

Yes, the MAX6831SZUT+ supports bidirectional µP reset pins via its active-low open-drain RESET output. When connected directly to a bidirectional reset I/O (e.g., Motorola 68HC11), a single external pullup resistor enables the µP to drive the line low for self-reset while allowing the MAX6831SZUT+ to assert reset during power faults. This eliminates level-shifting circuitry and simplifies PCB layout compared to push-pull alternatives.

What is the watchdog timeout period for MAX6831SZUT+ and how is it cleared?

The MAX6831SZUT+ features a nominal 1.6s watchdog timeout period (ranging from 0.8s to 2.6s over temperature). The internal timer is cleared on any rising or falling edge at the WDI pin, or automatically when RESET is asserted (e.g., during power-up or manual reset). If WDI remains static beyond timeout, the device asserts RESET for the full reset timeout period (≥140ms). Leaving WDI unconnected disables the watchdog function.

Can MAX6831SZUT+ operate reliably when VCC drops below 1.8V?

Yes, the MAX6831SZUT+ is guaranteed to assert valid RESET down to VCC = +1.0V across the full -40°C to +125°C temperature range. Its internal circuitry remains functional and comparators retain accuracy even at 1.2V minimum supply - enabling robust brownout detection in ultra-low-voltage systems such as energy-harvesting or coin-cell-powered devices where VCC may dip below standard logic thresholds.

How does the manual reset (MR) input behave on MAX6831SZUT+?

The MR input on MAX6831SZUT+ is active-low with an internal 50kΩ pullup to VCC. Pulling MR low forces RESET assertion immediately and holds it active for the full reset timeout period (≥140ms) after MR returns high. If unused, MR may be left floating (relying on internal pullup) or tied to VCC. No external debounce circuitry is required, as the device includes built-in glitch rejection (100ns minimum pulse rejection).