Analog Devices Inc./Maxim Integrated MAX6703ZKA

Overview

MAX6703ZKA from Maxim Integrated is an 8-pin SOT23 microprocessor supervisory circuit with active-low open-drain reset output, dual adjustable voltage monitoring (VCC + RST_IN1/RST_IN2), 1.6s watchdog timeout, 0.62V power-fail comparator input, and manual reset input - designed for triple-supply systems requiring precise brownout detection and fail-safe reset assertion in automotive and industrial controllers.

For engineers reviewing the MAX6703ZKA datasheet, MAX6703ZKA pinout, MAX6703ZKA application, or MAX6703ZKA equivalent, this device delivers guaranteed reset validity down to VCC = 1V, immunity to short VCC transients, and configurable thresholds for +2.5V/+3.0V/+3.3V/+5.0V rails - critical for reliable µP startup, power-down sequencing, and watchdog-triggered recovery in safety-critical embedded systems.

Technical Context

The MAX6703ZKA implements a triple-voltage supervision architecture: primary VCC monitoring at 2.32V (Z-suffix), plus two user-adjustable inputs (RST_IN1/RST_IN2) referenced to an internal 0.62V threshold via external resistor dividers. Reset assertion occurs if any monitored supply falls below its threshold and persists for 140–300ms after recovery.

Its independent watchdog timer monitors WDI activity with 1.6s timeout (typ), asserting WDO low on overflow or undervoltage; WDO deasserts only upon valid WDI edge or MR low pulse (A-version behavior). The 0.62V PFI comparator drives PFO for early power-fail warning, supporting orderly shutdown in systems with regulated I/O and core supplies.

Key Specifications

Pinout & Package

MAX6703ZKA uses an 8-pin SOT23-8 package (JEDEC MO-178 BA), 3.0mm × 1.75mm footprint, 0.65mm pitch, with exposed thermal pad option (not electrically connected). Pin 1 marked by dot; pins 1–4 on left side, 5–8 on right side when viewing top side with marking dot top-left.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6703AKA and TPS3808G33DBVR, MAX6703ZKA uniquely combines Z-suffix 2.32V precision threshold, dual adjustable inputs for triple-rail monitoring, and integrated PFI/PFO for predictive power-fail signaling - making it irreplaceable in compact, multi-supply safety-critical systems requiring coordinated reset and early warning.

Availability

MAX6703ZKA is available at Aetrix Electronics and suitable for automotive body control modules, industrial PLC I/O subsystems, and medical infusion pump controllers requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MAX6703ZKA 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 demanding industrial, automotive, and communications applications, emphasizing reliability, precision, and integration density.

The MAX6701–MAX6708 family targets space-constrained µP systems needing multivoltage supervision, watchdog safety, and power-fail warning - delivering four key functions (reset, watchdog, PFI/PFO, MR) in a single 8-pin SOT23 package.

FAQ

What is the exact reset threshold voltage of MAX6703ZKA and how is it specified?

The MAX6703ZKA has a nominal VCC reset threshold of 2.32V, corresponding to the 'Z' suffix in the Threshold Suffix Guide. This value is guaranteed over the full operating temperature range (-40°C to +125°C) with ±3% tolerance. The threshold is internally trimmed and tested; it applies specifically to the VCC supply input, while RST_IN1 and RST_IN2 use the internal 0.62V reference with external resistor dividers to set their trip points. MAX6703ZKA's 2.32V threshold makes it ideal for monitoring +2.5V rails with margin.

Does MAX6703ZKA support monitoring more than one supply voltage, and how is that implemented?

Yes, MAX6703ZKA supports triple-voltage monitoring: the primary VCC supply (2.32V threshold), plus two additional supplies via RST_IN1 and RST_IN2 inputs. Each of these inputs connects to an internal 0.62V comparator, so external resistor dividers scale higher voltages (e.g., +5V, +3.3V) down to 0.62V at the pin. Reset asserts if any of the three monitored supplies falls below its configured threshold. This architecture eliminates the need for multiple discrete supervisors in multi-rail systems.

What is the function of the PFI and PFO pins on MAX6703ZKA, and how do they differ from the reset inputs?

PFI (Power-Fail Input) is a high-impedance comparator input referenced to 0.62V, used to monitor a secondary supply (e.g., backup battery or auxiliary rail) via an external resistor divider. PFO (Power-Fail Output) is an active-low open-drain output that asserts when PFI falls below 0.62V. Unlike reset inputs, PFI/PFO operate independently of the main reset generator - enabling early warning and orderly shutdown without triggering a full system reset. In MAX6703ZKA, PFI/PFO are fully functional and electrically isolated from RST_IN1/RST_IN2.

How does the watchdog timer in MAX6703ZKA behave, and what happens to WDO during a VCC brownout?

The MAX6703ZKA watchdog timer times out after ~1.6s if WDI is not toggled. Its WDO output asserts low on timeout *or* whenever VCC, RST_IN1, or RST_IN2 falls below their respective thresholds - meaning WDO serves as both a software liveliness indicator and a hardware undervoltage flag. During a VCC brownout, WDO goes low immediately (within 5µs), regardless of WDI state. WDO deasserts only upon a valid WDI edge or pulling MR low - ensuring continuous fault indication until deliberate recovery action is taken.

What package type and pin compatibility does MAX6703ZKA have, and are there lead-free options?

MAX6703ZKA is supplied in an 8-pin SOT23-8 package (JEDEC MO-178 BA), measuring 3.0mm × 1.75mm with 0.65mm pitch. It shares identical pinout and footprint with all members of the MAX6701–MAX6708 family, including MAX6703AKA, MAX6705ZKA, and MAX6707ZKA. Lead-free versions are available: replace the '-T' suffix with '+T' (e.g., MAX6703ZKA+T) to specify RoHS-compliant packaging with matte tin lead finish.