Analog Devices Inc./Maxim Integrated MAX824ZEXK+T

Overview

MAX824ZEXK+T from Maxim Integrated is a 5-pin SC70-packaged microprocessor supervisory circuit with active-low and active-high reset outputs, watchdog timer (1.6s timeout), and precision 2.32V reset threshold for +2.5V supply monitoring. It guarantees RESET validity down to VCC = 1V, provides 140ms min power-on reset delay, and operates over -40°C to +85°C for embedded controller and portable equipment applications.

For engineers reviewing the MAX824ZEXK+T datasheet, MAX824ZEXK+T pinout, MAX824ZEXK+T application, or MAX824ZEXK+T equivalent, key selection criteria include its dual-reset polarity, SC70-5 package footprint, 2.32V threshold accuracy, watchdog immunity to software lockup, and compatibility with bidirectional µP reset pins requiring ≤400µA pullup current.

Technical Context

The MAX824ZEXK+T integrates a precision voltage comparator with 40ppm/°C temperature coefficient, a 1.6s watchdog timer cleared by WDI edge transitions, and dual complementary reset outputs driven by a single internal reset generator. Its reset timeout period is guaranteed at 140–280ms across temperature.

It features power-supply transient immunity via internal hysteresis (5mV for Z-suffix) and supports manual reset disable via open-circuit WDI. The device uses BiCMOS process technology (607 transistors) and draws only 2µA typical supply current in SC70 package at +25°C.

Key Specifications

Pinout & Package

MAX824ZEXK+T is housed in a 5-pin SC70-5 package (2.0mm × 2.1mm × 0.9mm), lead-free, tape-and-reel format (2500 pcs/reel).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX824ZEXK+T, MAX824REXK+T shifts reset activation to higher voltage for 3.3V systems but retains identical watchdog functionality and ultra-low current, while TPS3808G125DBVR trades watchdog capability and current efficiency for lower unit cost and simpler integration in static-voltage monitoring roles.

Availability

MAX824ZEXK+T is available at Aetrix Electronics and suitable for portable medical sensors, industrial PLC I/O modules, automotive body control units, and smart energy meters requiring stable component supply with full traceability and long-term lifecycle support.

Supply support for MAX824ZEXK+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) designs high-performance analog and mixed-signal ICs for industrial, automotive, communications, and computing markets, with emphasis on power management and reliability-critical functions.

The MAX823/MAX824/MAX825 family was engineered specifically for robust µP supervision in space-constrained, battery-operated, and noise-prone environments-delivering precision reset, watchdog safety, and minimal external component count.

FAQ

What is the exact reset threshold voltage of the MAX824ZEXK+T and how is it specified over temperature?

The MAX824ZEXK+T has a nominal reset threshold of 2.32V, with guaranteed limits of 2.25V to 2.38V over the full -40°C to +85°C operating range. This specification is validated per the Reset Threshold Table in the datasheet, and the device exhibits a temperature coefficient of 40ppm/°C, ensuring predictable drift across industrial temperatures. The MAX824ZEXK+T's 5mV hysteresis further stabilizes operation against supply noise.

Does the MAX824ZEXK+T support both active-low and active-high reset outputs simultaneously?

Yes, the MAX824ZEXK+T provides two dedicated reset outputs: pin 1 (RESET) is active-low, and pin 4 (RESET) is active-high-complementary signals generated from the same internal reset generator. This eliminates the need for external inverters in systems requiring both polarities, such as interfacing with legacy logic families or dual-supply µPs. Both outputs are guaranteed functional down to VCC = 1V.

How does the watchdog timer in the MAX824ZEXK+T behave when the WDI pin is left unconnected?

When WDI is unconnected, the MAX824ZEXK+T's internal watchdog timer is automatically disabled. The datasheet confirms that leaving WDI open or connecting it to a three-stated buffer disables the watchdog function. No reset will be asserted due to watchdog timeout under this condition, making the MAX824ZEXK+T operate solely as a voltage supervisor unless WDI is actively driven.

What is the supply current consumption of the MAX824ZEXK+T and under what conditions is it measured?

The MAX824ZEXK+T draws 2µA typical supply current, measured in SC70-5 package at TA = +25°C with MR and WDI unconnected. This ultra-low quiescent current is confirmed in the Electrical Characteristics table for MAX825T/S/R/Z/Y variants (which includes the Z-suffix), enabling multi-year operation in battery-backed applications. Current increases slightly at temperature extremes but remains below 6µA over full operating range.

Can the MAX824ZEXK+T interface directly with microcontrollers that have bidirectional reset pins?

Yes, the MAX824ZEXK+T can interface directly with µPs having bidirectional reset pins, such as the 68HC11. Its RESET output is designed to source up to 400µA (for T/S/R/Z/Y versions) when pulled high, allowing the µP to override the supervisor and force RESET low during normal operation. This bidirectional compatibility is explicitly verified in the "Interfacing to µPs with Bidirectional Reset Pins" section of the datasheet.