Analog Devices Inc./Maxim Integrated MAX811LEUS

Overview

MAX811LEUS from Maxim Integrated is an active-low microprocessor supervisory circuit in a 4-pin SOT143 package, designed to monitor 5V power supplies with a precision 4.63V reset threshold, 6µA supply current, and guaranteed RESET assertion down to VCC = 1V. It provides reliable power-on/brownout reset for embedded µP systems in portable and industrial equipment.

For engineers reviewing the MAX811LEUS datasheet, MAX811LEUS pinout, MAX811LEUS application, or MAX811LEUS equivalent, key selection criteria include reset threshold accuracy (±1.5% over temperature), manual reset input immunity (100ns glitch rejection), 140ms minimum reset timeout, and guaranteed logic-level validity during low-VCC operation.

Technical Context

The MAX811LEUS implements a precision bandgap-based voltage comparator with internal hysteresis and a monostable timer to generate a minimum 140ms active-low reset pulse after VCC rises above 4.63V. Its reset assertion remains valid even as VCC drops to 1V, ensuring deterministic µP initialization during brownout recovery.

It integrates a debounced manual reset input (MR) with 20kΩ internal pull-up, supporting TTL/CMOS-compatible triggering and guaranteeing 180ms reset hold time after MR release. The device ignores transients ≤40µs at 125mV comparator overdrive, enhancing noise immunity in electrically harsh environments.

Key Specifications

Pinout & Package

The MAX811LEUS is housed in a lead-free 4-pin SOT143 package (3.0mm × 1.75mm × 1.1mm), optimized for space-constrained PCB layouts and reflow soldering.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS3124E-46 and ADM6710L-46ARTZ-R7, the MAX811LEUS delivers superior low-VCC reset assurance (valid to 1V) and zero-component simplicity, making it optimal for cost-sensitive, space-constrained 5V systems where deterministic brownout recovery is mandatory.

Availability

MAX811LEUS is available at Aetrix Electronics and suitable for industrial PLC controllers, portable medical monitors, network edge routers, smart energy meters, and battery-backed data loggers requiring stable component supply and long-term lifecycle support.

Supply support for MAX811LEUS 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) is a semiconductor company specializing in analog, mixed-signal, and power-management ICs for industrial, communications, and consumer applications.

The MAX811/MAX812 family was designed specifically for low-cost, low-power microprocessor supervision in space- and current-constrained systems, targeting portable, industrial, and telecom equipment requiring precise, glitch-immune reset generation.

FAQ

What is the guaranteed reset threshold voltage tolerance for MAX811LEUS over temperature?

The MAX811LEUS has a nominal reset threshold of 4.63V with guaranteed tolerance of ±1.5% over the full -40°C to +85°C operating temperature range. This specification ensures reliable reset assertion before the 5V supply falls outside its ±5% regulation window, and is validated by six-sigma design limits-not just room-temperature testing. The tempco is 30ppm/°C, contributing to tight threshold stability across industrial environments.

Does MAX811LEUS require external components to function as a complete reset supervisor?

No, the MAX811LEUS requires no external components to operate as a fully functional reset supervisor. It integrates a precision voltage reference, comparator, monostable timer, and 20kΩ internal pull-up resistor on the MR pin. Only the VCC, GND, MR (optional), and RESET connections are needed. This eliminates BOM cost, layout area, and calibration effort-making MAX811LEUS ideal for high-volume, cost-sensitive designs where reliability and simplicity are paramount.

How does MAX811LEUS ensure reset validity when VCC drops below 1.5V?

The MAX811LEUS guarantees that its active-low RESET output remains a valid logic low down to VCC = 1V, unlike many supervisors that lose output control below 2V. Below 1V, RESET transitions to a high-impedance open-circuit state. For applications requiring validity to 0V, a 100kΩ pull-down resistor on the RESET pin ensures deterministic low state-even during deep brownout-without loading the output under normal operation.

Can MAX811LEUS be used with microprocessors that have bidirectional reset pins?

Yes, MAX811LEUS can interface safely with µPs having bidirectional reset I/O (e.g., Motorola 68HC11), but requires a 4.7kΩ series resistor between its RESET output and the µP pin. This prevents contention when the µP attempts to drive the line low while MAX811LEUS holds it low-or vice versa. The resistor isolates the outputs while preserving signal integrity and timing, as confirmed in Maxim's Application Note 3992 and Figure 3 of the MAX811/MAX812 datasheet.

What is the maximum duration of a VCC transient that MAX811LEUS will ignore without asserting reset?

At a comparator overdrive of 125mV (i.e., VCC dipping 125mV below the 4.63V threshold), the MAX811LEUS ignores negative-going transients ≤40µs in duration. This immunity is specified for the L/M versions (like MAX811LEUS) and is enabled by internal filtering that rejects fast glitches. Adding a 0.1µF ceramic capacitor close to the VCC pin further enhances immunity against longer or larger transients encountered in noisy industrial power rails.