Analog Devices Inc./Maxim Integrated MAX1232MJA

Overview

MAX1232MJA from Maxim Integrated is a microprocessor supervisory circuit designed for high-reliability embedded systems operating across -55°C to +125°C. It provides precision power-supply monitoring (4.5V or 4.75V trip points), a programmable watchdog timer (150ms/600ms/1.2s), and dual active-high/active-low reset outputs with 250ms minimum pulse width. It requires no external components and replaces the DS1232 in harsh-environment μP systems such as aerospace avionics and military control units.

For engineers reviewing the MAX1232MJA datasheet, MAX1232MJA pinout, MAX1232MJA application, or MAX1232MJA equivalent, key selection criteria include its extended temperature range (-55°C to +125°C), CERDIP-8 hermetic package, 5%/10% selectable voltage tolerance, debounced manual reset input, and guaranteed 250ms reset pulse duration under brownout and power-up conditions.

Technical Context

The MAX1232MJA integrates three core supervision functions: a precision voltage detector with digitally selectable 5% (4.62V typ) or 10% (4.37V typ) VCC tolerance, a falling-edge-triggered watchdog timer whose timeout is set by TD pin state (GND = 150ms, open = 600ms, VCC = 1.2s), and a debounced pushbutton reset input (PBRST) that ignores pulses <1ms and guarantees recognition of ≥20ms low assertions.

It delivers dual complementary reset outputs: RST (active-high, push-pull) and RST (active-low, open-drain), enabling direct interface with both standard logic and pull-up–dependent microcontroller reset inputs. All timing parameters-including reset active time (250–1000ms), VCC detect-to-reset delay (100ns–1000ms), and ST strobe response-are fully specified over the full -55°C to +125°C operating range.

Key Specifications

Pinout & Package

MAX1232MJA is housed in an 8-pin CERDIP (Ceramic Dual In-line Package) with hermetic sealing, rated for military-grade reliability and long-term operation in high-vibration, high-humidity, or radiation-prone environments. Pin 1 is PBRST; pin 2 is TD; pin 3 is TOL; pin 4 is GND; pin 5 is RST (active-high); pin 6 is RST (active-low, open-drain); pin 7 is ST; pin 8 is VCC.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX1232EWE and DS1232L, the MAX1232MJA uniquely combines military-grade temperature range, hermetic CERDIP packaging, programmable watchdog timeout, and ultra-low power-making it the sole option for new high-reliability designs demanding all four attributes simultaneously.

Availability

MAX1232MJA is available at Aetrix Electronics and suitable for aerospace avionics, military vehicle control, and downhole instrumentation requiring stable component supply across extended temperature extremes and long product lifecycles.

Supply support for MAX1232MJA 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, mixed-signal, and high-reliability semiconductor solutions for demanding industrial, automotive, and aerospace applications.

The MAX1232 family was developed specifically to replace legacy supervisory ICs with enhanced accuracy, lower power, and flexible configuration-targeting μP-based systems where power integrity, software reliability, and environmental robustness are critical.

FAQ

What is the operating temperature range of the MAX1232MJA?

The MAX1232MJA is rated for continuous operation from -55°C to +125°C. This extended temperature range is validated per MIL-STD-883 test methods and makes the MAX1232MJA suitable for deployment in military, aerospace, and oilfield applications where ambient conditions exceed commercial or industrial limits. Its CERDIP-8 package contributes to thermal stability and long-term parameter retention across this full range.

Does the MAX1232MJA require external components to function?

No, the MAX1232MJA requires no external components to perform full supervisory operation. It integrates an internal voltage reference, precision comparator, watchdog oscillator, debounce logic, and dual reset drivers. The only external connections needed are VCC, GND, and the optional pull-up resistor for the open-drain RST output - eliminating BOM cost, board space, and calibration effort associated with discrete supervision circuits.

How is the watchdog timeout configured on the MAX1232MJA?

The watchdog timeout on the MAX1232MJA is configured solely by the voltage state of the TD pin (Pin 2): connecting TD to GND selects 150ms, leaving TD open selects 600ms, and connecting TD to VCC selects 1.2s. This digital selection method avoids timing capacitors or resistors, ensures consistent timeout values across temperature, and allows field reconfiguration via simple jumper or solder bridge.

What is the function of the TOL pin on the MAX1232MJA?

The TOL pin (Pin 3) on the MAX1232MJA selects the VCC voltage tolerance threshold: tying TOL to GND configures a 5% trip point (~4.62V), while tying TOL to VCC configures a 10% trip point (~4.37V). This digital selection replaces resistor dividers used in older supervisors, enabling rapid design iteration and eliminating tolerance drift due to resistor aging or temperature coefficient mismatch.

Can the MAX1232MJA replace the DS1232 in existing designs?

Yes, the MAX1232MJA is a plug-in upgrade for the DS1232, sharing identical pinout, reset behavior, and functional scope. However, the MAX1232MJA adds programmable watchdog timeout, selectable voltage tolerance, and consumes only 1/10th the power. When replacing DS1232 in legacy designs, verify that the TD and TOL pins are properly terminated - floating TD defaults to 600ms timeout, and floating TOL defaults to 10% tolerance.