Analog Devices Inc./Maxim Integrated MAX824ZEXK+

Overview

MAX824ZEXK+ 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. It monitors +2.5V/+3V/+3.3V power rails in embedded controllers and portable equipment, asserting reset for VCC down to 1V and ignoring fast transients.

For engineers reviewing the MAX824ZEXK+ datasheet, MAX824ZEXK+ pinout, MAX824ZEXK+ application, or MAX824ZEXK+ equivalent, this page delivers verified functional roles, SC70-5 package mapping, reset timing behavior, watchdog interaction logic, and direct alternative options for brownout-critical µP monitoring.

Technical Context

The MAX824ZEXK+ integrates dual-reset output logic (RESET and RESET) driven by a precision voltage comparator with 2.32V threshold and 5mV hysteresis, enabling reliable detection of VCC dips below nominal supply. Its watchdog timer clears on any WDI edge and triggers reset if no transition occurs within 1.12–2.40s.

Reset assertion is guaranteed for VCC ≥ 1V, with 140–280ms timeout after VCC recovery; the internal 52kΩ MR pullup supports manual reset via momentary switch without external components. All specifications are fully characterized from –40°C to +85°C.

Key Specifications

Pinout & Package

MAX824ZEXK+ uses the 5-pin SC70-5 package (2.0mm × 2.1mm × 0.9mm), optimized for space-constrained portable and automotive applications. Pin numbering follows standard SC70 top-view orientation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX824ZEXK+, MAX824YEXK+ offers lower threshold for sub-2.3V rails but identical supervision architecture, while TLV803EB23DBVR reduces cost and complexity at the expense of watchdog and dual-output capability-making it viable only in non-safety-critical, reset-only use cases.

Availability

MAX824ZEXK+ is available at Aetrix Electronics and suitable for industrial PLC controllers, medical portable monitors, automotive body control modules, smart energy meters, and critical µP monitoring applications requiring stable component supply, lead-free compliance, and tape-and-reel delivery.

Supply support for MAX824ZEXK+ 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 industrial, automotive, and computing applications, with expertise in power management and reliability-critical supervision.

The MAX823/MAX824/MAX825 family was engineered specifically for microprocessor reset supervision in space- and power-constrained systems, integrating watchdog, manual reset, and dual-output logic into minimal 5-pin SC70/SOT23 packages.

FAQ

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

The MAX824ZEXK+ has a nominal reset threshold of 2.32V, with ±15mV tolerance at +25°C and 40ppm/°C temperature coefficient. Over the full –40°C to +85°C operating range, the threshold remains within 2.25V to 2.38V, ensuring consistent brownout detection for 2.5V systems across industrial environments. This specification is guaranteed per the Electrical Characteristics table in the MAX824ZEXK+ datasheet.

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

Yes, MAX824ZEXK+ provides simultaneous active-low RESET (pin 1) and active-high RESET (pin 4) outputs. These are complementary signals generated from the same internal comparator and timer, allowing direct interfacing to microcontrollers or peripherals requiring either polarity without external inversion. The outputs are synchronized and share identical timing characteristics including 140–280ms timeout.

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

When WDI is left unconnected, the MAX824ZEXK+ watchdog function is automatically disabled. Internally, the WDI node is driven low for 7/8 of the timeout period and high for 1/8, generating a self-clearing pulse every ~1.4s-well within the 1.6s timeout window. This prevents unintended resets and eliminates the need for external pull-up/down resistors, simplifying design for applications not requiring watchdog supervision.

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

The MAX824ZEXK+ 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 maintained across the full –40°C to +85°C temperature range and enables multi-year battery life in portable and remote sensor applications where continuous supervision is required.

Can MAX824ZEXK+ operate reliably during fast VCC transients, and what is its immunity specification?

Yes, MAX824ZEXK+ is designed to ignore fast negative-going VCC transients. It tolerates pulses up to 100ns wide when the overdrive (VRST − VCC) is 200mV, as shown in the Typical Operating Characteristics graph. This immunity prevents spurious resets caused by switching regulator noise or ESD-induced supply glitches, making it suitable for electrically noisy environments like automotive and industrial control systems.