Analog Devices Inc./Maxim Integrated MAX6423XS31

Overview

MAX6423XS31 from Maxim Integrated is a low-power microprocessor supervisor IC that monitors VCC supply voltage and asserts an active-low open-drain RESET signal when voltage falls below 3.075V (typical), with capacitor-adjustable reset timeout, guaranteed operation down to VCC = 1V, and 1.6µA typical quiescent current - used in battery-powered controllers and portable medical instruments for reliable power-on reset sequencing.

For engineers reviewing the MAX6423XS31 datasheet, MAX6423XS31 pinout, MAX6423XS31 application, or MAX6423XS31 equivalent, this page delivers verified electrical parameters, SC70-4 package mapping, open-drain reset interface design guidance, and validated alternative parts for critical µP monitoring in automotive and embedded systems.

Technical Context

The MAX6423XS31 implements a precision voltage comparator with laser-trimmed reference and hysteresis (4×VTH), coupled to a 240nA current source that charges an external SRT capacitor to generate a programmable reset timeout delay. Its open-drain RESET output supports wired-OR logic and multi-supply interfacing up to 5.5V.

It operates across –40°C to +125°C, maintains reset validity down to VCC = 1V, and rejects short VCC transients (e.g., ≤50µs for 100mV overdrive), making it suitable for brownout detection in noise-prone industrial environments without false triggering.

Key Specifications

Pinout & Package

MAX6423XS31 is housed in a 4-pin SC70-4 package (2.0mm × 2.1mm, 0.5mm pitch), optimized for space-constrained portable designs. Pin 1 is SRT (Set Reset Timeout), Pin 2 is GND, Pin 3 is RESET (open-drain), and Pin 4 is VCC.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6423XS31, MAX6423US31-T provides identical electrical behavior in a thermally robust SOT143 package, while NCP302LSN30T1G trades timeout flexibility and open-drain versatility for lower cost and simpler BOM - selection depends on layout constraints and system-level reset coordination requirements.

Availability

MAX6423XS31 is available at Aetrix Electronics and suitable for battery-powered medical monitors, automotive body control modules, and industrial sensor nodes requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MAX6423XS31 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 management, sensing, and interface applications in industrial, automotive, and medical markets.

The MAX6421–MAX6426 family was engineered specifically for ultra-low-power, capacitor-programmable reset supervision in space- and energy-constrained embedded systems - emphasizing accuracy, transient immunity, and multi-supply interoperability.

FAQ

What is the exact reset threshold voltage of MAX6423XS31?

The MAX6423XS31 has a nominal reset threshold of 3.075V, with ±2.5% tolerance over the full –40°C to +125°C temperature range. This value is factory-laser-trimmed and corresponds to the "31" suffix per Table 1 in the datasheet. The device asserts RESET when VCC falls below this threshold and holds it low for the capacitor-set timeout period after VCC rises above it. MAX6423XS31 maintains this accuracy without external components.

How do I calculate the reset timeout capacitor for MAX6423XS31?

Use the formula CSRT = (tRP − 275µs) / 2.73×10⁶, where tRP is your desired timeout in seconds and CSRT is in farads. For example, a 5ms timeout requires CSRT = (0.005 − 0.000275) / 2.73×10⁶ ≈ 1.73nF. MAX6423XS31 specifies ceramic capacitors with leakage <10nA; X7R or C0G types are recommended. The SRT pin must be routed short and away from noisy traces to preserve timing accuracy.

Can MAX6423XS31 drive a 1.8V microcontroller reset input?

Yes, MAX6423XS31 can interface directly with a 1.8V µP reset input using its open-drain RESET output. Connect a 10kΩ pullup resistor from the RESET pin to the 1.8V rail. When asserted, MAX6423XS31 pulls RESET low to <0.3V (ISINK = 500µA), satisfying 1.8V logic low requirements. When deasserted, the pullup brings RESET to 1.8V - enabling seamless voltage translation without level-shifters. This capability is intrinsic to MAX6423XS31's open-drain architecture.

Does MAX6423XS31 require an external pullup resistor on the RESET pin?

Yes, MAX6423XS31 requires an external pullup resistor on the RESET pin because it features an open-drain output. A 10kΩ to 100kΩ resistor connected between RESET and the target logic rail (e.g., 1.8V, 3.3V, or 5V) is necessary to establish a valid high state when RESET is deasserted. The resistor value balances leakage current handling and rise time; 10kΩ is typical for fast edges, while 100kΩ minimizes current draw. Omitting the pullup renders MAX6423XS31 nonfunctional.

What is the minimum VCC voltage at which MAX6423XS31 guarantees valid RESET operation?

MAX6423XS31 guarantees valid RESET assertion and deassertion down to VCC = 1.0V, as specified in the Electrical Characteristics table. Below 1.0V, sink/source capability degrades significantly. This feature ensures deterministic reset behavior during deep brownout conditions common in battery-powered systems. For applications requiring RESET validity all the way to 0V, a 100kΩ pulldown resistor from RESET to GND is recommended - a design consideration explicitly documented for MAX6423XS31 in the Applications Information section.