Analog Devices Inc./Maxim Integrated MAX6387XS44D3

Overview

MAX6387XS44D3 from Maxim Integrated is a low-power, dual-voltage microprocessor supervisory circuit with active-low push-pull reset output, factory-set 4.38V VCC reset threshold (±2.5% over -40°C to +125°C), 140ms minimum reset timeout, and auxiliary RESET IN input for monitoring a second voltage source. It operates from 1.0V to 5.5V supply and consumes only 3µA at +1.8V, targeting power-sensitive embedded systems requiring reliable brownout detection.

For engineers reviewing the MAX6387XS44D3 datasheet, MAX6387XS44D3 pinout, MAX6387XS44D3 application, or MAX6387XS44D3 equivalent, key selection criteria include its dual-monitoring capability (VCC + RESET IN), guaranteed reset validity down to VCC = 1V, ±2.5% threshold accuracy over full temperature range, and SC70-4 package compatibility with space-constrained PCB layouts.

Technical Context

The MAX6387XS44D3 integrates two independent voltage comparators: one monitors VCC against a fixed 4.38V threshold, while the second compares an external voltage applied to the RESET IN pin against an internal +1.27V reference. Reset asserts when either monitored voltage falls below its respective threshold and remains asserted for a guaranteed minimum 140ms after recovery.

Its push-pull active-low RESET output drives high-impedance during deassertion and sinks current during assertion, eliminating need for external pull-up resistors. The device features negative-going VCC transient immunity up to 35µs for 100mV overdrive and guarantees correct logic state down to VCC = 1V - critical for controlled power-down sequencing in battery-powered devices.

Key Specifications

Pinout & Package

MAX6387XS44D3 is housed in a lead-free 4-pin SC70 package (X4-1), measuring 1.5mm × 1.0mm × 0.8mm, suitable for ultra-compact PCB designs. Pin 1 is marked with a dot; pin numbering follows standard SC70 orientation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6387LT44D3, the MAX6387XS44D3 offers identical functionality in a smaller SC70-4 package ideal for space-constrained designs, while TLV809E43DBZR provides basic reset functionality at lower cost but omits the critical RESET IN feature required for dual-rail supervision.

Availability

MAX6387XS44D3 is available at Aetrix Electronics and suitable for industrial power monitoring, portable medical sensors, battery-powered IoT gateways, and dual-rail embedded controllers requiring stable component supply and long-term production continuity.

Supply support for MAX6387XS44D3 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 precision analog, mixed-signal, and power management ICs for industrial, communications, and consumer applications.

The MAX6381–MAX6390 family was designed specifically for low-power, dual-voltage microprocessor supervision in space- and energy-constrained systems - emphasizing factory-trimmed accuracy, guaranteed operation down to 1V, and compact packaging.

FAQ

What is the exact reset threshold voltage of MAX6387XS44D3 and how stable is it over temperature?

The MAX6387XS44D3 has a factory-set VCC reset threshold of 4.38V nominal, with a guaranteed range of 4.27V (min) to 4.48V (max) across -40°C to +125°C. Its ±2.5% accuracy over this full temperature range and 60ppm/°C tempco ensure minimal drift in brownout detection points - critical for consistent system behavior in harsh environments.

Does MAX6387XS44D3 support monitoring of a second voltage rail, and how is it configured?

Yes, MAX6387XS44D3 supports dual-rail supervision via its dedicated RESET IN pin. This pin compares an external voltage to an internal +1.27V reference. To configure a custom threshold (e.g., 3.3V), connect a resistor divider between the target rail and GND, with the midpoint fed to RESET IN. The MAX6387XS44D3 asserts reset if either VCC < 4.38V or RESET IN < 1.27V.

What is the function of the RESET output on MAX6387XS44D3, and does it require an external pull-up resistor?

The RESET output on MAX6387XS44D3 is an active-low push-pull driver. It actively pulls low during reset assertion and actively drives high during deassertion. Because it is push-pull, no external pull-up resistor is required - simplifying design, reducing component count, and ensuring fast, well-defined logic transitions without reliance on external biasing.

How long does the reset signal remain asserted after VCC recovers above the threshold in MAX6387XS44D3?

The MAX6387XS44D3 guarantees a minimum reset timeout period of 140ms after VCC rises above the 4.38V threshold. This fixed delay is internally generated and independent of supply voltage or temperature - ensuring sufficient hold time for microprocessors and FPGAs to complete internal initialization before release, even under worst-case conditions.

Can MAX6387XS44D3 operate reliably at very low supply voltages, and what is its minimum functional VCC?

Yes, MAX6387XS44D3 is guaranteed to maintain valid reset output logic states down to VCC = 1.0V. Its internal circuitry continues to monitor thresholds and assert/deassert RESET correctly within this range - enabling controlled shutdown sequencing in battery-powered devices where supply voltage decays gradually, preventing erratic µP behavior during brownout.