Analog Devices Inc./Maxim Integrated MAX823MEXK+T

Overview

MAX823MEXK+T from Maxim Integrated is a 5-pin SC70-packaged microprocessor supervisory circuit with active-low reset, watchdog timer, and manual reset input. It monitors +4.38V power supplies, asserts reset down to VCC = 1V, provides 140ms min power-on reset timeout, and features 1.6s watchdog timeout. It is used in embedded controllers and critical µP monitoring where supply transient immunity and guaranteed low-voltage reset assertion are required.

For engineers reviewing the MAX823MEXK+T datasheet, MAX823MEXK+T pinout, MAX823MEXK+T application, or MAX823MEXK+T equivalent, key selection criteria include reset threshold accuracy (4.38V ±7mV), watchdog timeout stability over temperature, SC70-5 package compatibility, and support for manual reset with internal 52kΩ pullup.

Technical Context

The MAX823MEXK+T integrates a precision voltage comparator with 40ppm/°C temperature coefficient, a monostable reset timer with 140–280ms timeout, and a watchdog timer with 1.12–2.40s timeout. Its reset output sources up to 150µA at 0.8×VCC and sinks 3.2mA at 0.4V, ensuring reliable interfacing with bidirectional µP reset pins.

It employs BiCMOS process technology (607 transistors) and features internal WDI drive logic that services the watchdog when unconnected-eliminating external components. The device ignores fast VCC transients by design, with validated immunity to negative-going glitches up to 100ns at 100mV overdrive.

Key Specifications

Pinout & Package

MAX823MEXK+T is housed in a 5-pin SC70-5 package (2.0mm × 2.1mm × 0.9mm), lead-free, tape-and-reel format.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX823MEXK+T, MAX823MEUK+T offers identical electrical behavior in a thermally robust SOT23 package, while TPS3808G33DBVR provides lower quiescent current but omits critical watchdog and manual reset functions-making it unsuitable as a functional replacement.

Availability

MAX823MEXK+T is available at Aetrix Electronics and suitable for embedded controllers, automotive body electronics, and portable medical instrumentation requiring stable component supply, long-term lifecycle support, and lead-free compliance.

Supply support for MAX823MEXK+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 precision analog and mixed-signal ICs for power, sensing, and interface applications, with emphasis on reliability and integration.

The MAX823 family targets microprocessor supervision in space-constrained, mission-critical systems-delivering reset, watchdog, and manual reset in a single 5-pin SC70 device with guaranteed operation down to 1V.

FAQ

What is the reset threshold voltage of the MAX823MEXK+T and how tightly is it specified?

The MAX823MEXK+T has a nominal reset threshold of 4.38V, with a tolerance of ±7mV at +25°C and ±12mV over the full -40°C to +85°C temperature range. This precision ensures reliable brownout detection in +4.5V systems without requiring external calibration. The MAX823MEXK+T achieves this using a trimmed bandgap reference and low-drift comparator architecture.

Does the MAX823MEXK+T require external components to operate?

No, the MAX823MEXK+T requires no external components for basic operation: its internal 52kΩ MR pullup resistor eliminates the need for an external pullup, the watchdog timer needs no external capacitor, and the reset timeout is fully integrated. A 0.1µF VCC bypass capacitor is recommended for enhanced transient immunity but is not mandatory for functionality. The MAX823MEXK+T is designed for drop-in deployment in space-sensitive designs.

How does the MAX823MEXK+T handle VCC transients, and what is its immunity specification?

The MAX823MEXK+T is specifically designed to ignore fast transients on VCC, with documented immunity to negative-going glitches ≤100ns wide when the overdrive (VRST – VCC) is ≤100mV. This prevents spurious resets during switching noise or ESD events. The device's internal comparator hysteresis (5–10mV) and propagation delay filtering further enhance robustness. MAX823MEXK+T maintains correct reset state even during such transients.

Can the watchdog function of the MAX823MEXK+T be disabled, and how?

Yes, the watchdog function of the MAX823MEXK+T can be disabled by leaving the WDI pin unconnected or by connecting it to a three-stated (high-impedance) driver. When unconnected, the internal WDI driver toggles low-high-low every ~1.4s, automatically clearing the 1.6s timer and preventing timeout. This behavior is inherent to the MAX823MEXK+T design and requires no configuration bits or external signals.

What is the maximum operating temperature range for the MAX823MEXK+T?

MAX823MEXK+T is rated for operation from -40°C to +85°C, as confirmed in the Ordering Information table for the EXK suffix variant in SC70-5 package. This range is fully supported by electrical specifications including reset threshold, supply current, and watchdog timeout. The MAX823MEXK+T is not qualified for +125°C operation-that rating applies only to the UK-suffixed SOT23 variants like MAX823MEUK+T.