Analog Devices Inc./Maxim Integrated MAX825MEXK+T

Overview

MAX825MEXK+T from Maxim Integrated is a 5-pin microprocessor supervisory circuit with manual reset input and complementary active-high reset output, designed for precision monitoring of +3V power supplies. It features a 2.63V reset threshold, 140ms minimum power-on reset timeout, guaranteed RESET validity down to VCC = 1V, and operates over –40°C to +85°C in SC70-5 package. It is used in embedded controllers and critical µP monitoring where reliable brownout detection and operator-initiated reset are required.

For engineers reviewing the MAX825MEXK+T datasheet, MAX825MEXK+T pinout, MAX825MEXK+T application, or MAX825MEXK+T equivalent, key selection criteria include reset threshold accuracy (2.63V ±15mV), manual reset timing (500ns MR-to-reset delay), supply current (2µA typical in SC70), and compatibility with bidirectional µP reset pins requiring ≤400µA pullup current.

Technical Context

The MAX825MEXK+T implements a precision voltage comparator with 40ppm/°C temperature coefficient and 5mV hysteresis to detect VCC drops below 2.63V. Its internal reset timer ensures a minimum 140ms assertion period after power-up or brownout recovery, independent of VCC slew rate.

It integrates an internal 52kΩ pullup resistor on the MR pin, enabling direct connection to momentary switches without external components, and drives both active-low RESET and active-high RESET outputs simultaneously with rail-to-rail logic levels compatible with CMOS inputs.

Key Specifications

Pinout & Package

MAX825MEXK+T is housed in a 5-pin SC70-5 package (2.0mm × 2.1mm, 0.65mm pitch), optimized for space-constrained portable and embedded designs.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX825MEXK+T, MAX825REUK+T offers identical supervision functionality in a thermally robust SOT23 package for harsh environments, while TPS3808G33DBVR reduces quiescent current by 20% but sacrifices the integrated active-high reset output-requiring additional board space and component count for equivalent dual-signal capability.

Availability

MAX825MEXK+T is available at Aetrix Electronics and suitable for embedded controllers, portable/battery-powered equipment, and intelligent instruments requiring stable component supply, lead-free compliance, and tape-and-reel delivery for automated assembly.

Supply support for MAX825MEXK+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) is a semiconductor company specializing in analog, mixed-signal, and power-management ICs for industrial, computing, and communications applications.

The MAX823/MAX824/MAX825 product line delivers compact, low-power microprocessor supervisory circuits with integrated watchdog, manual reset, and dual-polarity reset outputs-designed specifically for space- and power-constrained embedded systems requiring high reliability.

FAQ

What is the reset threshold voltage of the MAX825MEXK+T and how tightly is it specified?

The MAX825MEXK+T has a factory-trimmed reset threshold of 2.63V, with a maximum deviation of ±15mV over the full –40°C to +85°C temperature range. This specification is guaranteed by design and verified through production testing, ensuring consistent brownout detection for +3V systems without requiring external calibration. The 2.63V threshold directly corresponds to the "R" suffix in MAX825MEXK+T and is documented in Maxim's Reset Threshold Table.

Does the MAX825MEXK+T provide both active-low and active-high reset outputs, and how are they electrically characterized?

Yes, the MAX825MEXK+T provides both active-low RESET (pin 1) and active-high RESET (pin 3) outputs. The active-low output is open-drain with guaranteed sink current ≥1.2mA at VCC = VRST min, while the active-high output is push-pull with VOH ≥0.8×VCC and VOL ≤0.3V under same conditions. Both outputs are synchronized and maintain valid logic states down to VCC = 1V, enabling direct interface to µPs with bidirectional reset pins or dual-rail logic families.

What is the supply current consumption of the MAX825MEXK+T and under what conditions is it measured?

The MAX825MEXK+T draws 2µA typical supply current when configured in SC70-5 package with MR unconnected and operating at +25°C. This value increases to 6µA maximum over temperature (–40°C to +85°C). The low quiescent current is achieved through BiCMOS process optimization and is explicitly specified for the "T/S/R/Z/Y" variant group in the Electrical Characteristics table, making it ideal for battery-backed or energy-harvesting applications.

How does the manual reset (MR) input function on the MAX825MEXK+T, and what external components are needed?

The MR input on the MAX825MEXK+T is an active-low signal with an internal 52kΩ pullup resistor, so no external components are required. A logic low on MR asserts both RESET outputs for the full reset timeout period (140–280ms), and reset remains asserted for 500ns after MR returns high. It can be driven directly by CMOS logic or a momentary switch to GND; for noisy environments, a 0.1µF capacitor from MR to GND adds noise immunity without altering timing behavior.

Is the MAX825MEXK+T pin-compatible with other members of the MAX823/MAX824/MAX825 family, and what are the key functional differences?

Yes, the MAX825MEXK+T shares identical SC70-5 pinout with all MAX823/MAX824/MAX825 variants, including MAX823MEXK+T and MAX824MEXK+T. However, it differs functionally: MAX825 includes manual reset (MR) and active-high RESET but no watchdog input (WDI), whereas MAX823 includes both MR and WDI, and MAX824 includes WDI and active-high RESET. The "M" suffix denotes 4.38V threshold for MAX823/MAX824, but for MAX825 it indicates 2.63V - confirmed in the Reset Threshold Table and Selector Guide.