Analog Devices Inc./Maxim Integrated MAX6389XS20D1

Overview

MAX6389XS20D1 from Maxim Integrated is a low-power, open-drain active-low microprocessor supervisory circuit designed for single-voltage monitoring in space-constrained embedded systems. It features a factory-set 2.00V ±2.5% reset threshold, 140ms minimum VCC reset timeout, and operates across -40°C to +125°C with only 3µA supply current at 1.8V. It is used in portable battery-powered equipment to ensure reliable µP reset during brownout conditions.

For engineers reviewing the MAX6389XS20D1 datasheet, MAX6389XS20D1 pinout, MAX6389XS20D1 application, or MAX6389XS20D1 equivalent, key selection considerations include its open-drain output configuration, auxiliary RESET IN capability for dual-rail monitoring, guaranteed reset validity down to VCC = 1V, and SC70-4 package compatibility with high-density PCB layouts.

Technical Context

The MAX6389XS20D1 integrates a precision voltage comparator referenced to an internal 1.27V bandgap, enabling accurate detection of VCC falling below 2.00V. Its auxiliary RESET IN input compares external voltage against this same reference, supporting user-configurable secondary rail monitoring via resistor-divider networks.

It employs a temperature-stable monolithic timer for the 140ms reset timeout (±20% over temperature), with negative-going VCC transient immunity up to 35µs at 100mV overdrive. The open-drain RESET output requires an external pullup and remains valid down to VCC = 1V, ensuring deterministic behavior during deep power-down sequences.

Key Specifications

Pinout & Package

MAX6389XS20D1 is housed in a lead-free 4-pin SC70 package (X4-1), measuring 1.5mm × 1.0mm × 0.8mm, optimized for ultra-compact PCB layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6389LT20D1, the MAX6389XS20D1 offers identical supervision functionality in a 35% smaller footprint-critical for wearables and miniaturized modules-while TLV803EB20DBZR provides lower unit cost but sacrifices automotive temperature range and dual-monitoring flexibility essential for robust system-level reset management.

Availability

MAX6389XS20D1 is available at Aetrix Electronics and suitable for battery-powered IoT sensors, automotive body control modules, industrial PLC I/O cards, and medical wearable monitors requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MAX6389XS20D1 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) is a semiconductor company specializing in high-performance analog, mixed-signal, and power management ICs for industrial, automotive, communications, and computing markets.

The MAX6381–MAX6390 family was engineered to deliver ultra-low-power, precision voltage supervision in miniature packages for next-generation embedded systems where board space, power budget, and thermal resilience are critical constraints.

FAQ

What is the exact reset threshold voltage of MAX6389XS20D1 and how tightly is it specified?

The MAX6389XS20D1 has a factory-set reset threshold of 2.00V, with a guaranteed tolerance of ±2.5% over the full operating temperature range (-40°C to +125°C). This specification is confirmed in the Electrical Characteristics table of the official Maxim datasheet, where VTH min = 1.95V, nominal = 2.00V, and max = 2.05V at TA = -40°C to +125°C. The MAX6389XS20D1 achieves this accuracy using laser-trimmed on-chip resistors and a stable bandgap reference.

Does MAX6389XS20D1 support monitoring of a second voltage rail, and if so, how is it implemented?

Yes, MAX6389XS20D1 supports dual-rail supervision via its dedicated RESET IN pin. This input connects to an internal comparator referenced to a precise 1.27V bandgap voltage. To monitor a second rail (e.g., 3.3V or 2.5V), a resistor divider is placed between that rail and GND, with the midpoint fed to RESET IN. The MAX6389XS20D1 asserts reset if either VCC falls below 2.00V or the voltage at RESET IN drops below 1.27V, providing independent fault detection for two critical supplies.

What is the function of the RESET output on MAX6389XS20D1, and what external components are required?

The RESET output of MAX6389XS20D1 is an open-drain, active-low signal. It requires an external pullup resistor to the host system's logic rail (e.g., 3.3V or 5V) to generate a valid high level when deasserted. When asserted (low), it sinks current to ground; typical sink capability is 80µA at VOL ≤ 0.3V. No pullup is integrated internally, so omission of the external resistor will result in floating or undefined reset signaling. This architecture enables wired-OR bus configurations and voltage-level translation.

What is the minimum supply voltage at which MAX6389XS20D1 guarantees correct RESET output logic state?

The MAX6389XS20D1 guarantees valid RESET output logic state down to VCC = 1.0V, as explicitly stated in the Electrical Characteristics table under "RESET Output State Guaranteed Valid Down to VCC = 1V". This means the device continues to assert or deassert the open-drain RESET line correctly-even during deep brownout-until VCC collapses below 1.0V. This feature prevents spurious resets or failures to assert reset during critical low-voltage transients, a key reliability differentiator versus competitors with 1.5V or higher minimum operation limits.

Is MAX6389XS20D1 pin-compatible with other devices in the MAX6381–MAX6390 family, and which ones share the same SC70-4 footprint?

Yes, MAX6389XS20D1 is pin-compatible within the 4-pin SC70 variant group of the MAX6381–MAX6390 family. Specifically, it shares identical pinout and footprint with MAX6384XSxxDx, MAX6385XSxxDx, MAX6386XSxxDx, MAX6387XSxxDx, MAX6388XSxxDx, MAX6389XSxxDx, and MAX6390XSxxDx-all designated with the "XS" prefix and packaged in SC70-4 (X4-1). This allows direct substitution among these variants when only reset threshold or timeout differs, simplifying design reuse and inventory management.