Analog Devices Inc./Maxim Integrated MAX6390XS31D7+

Overview

MAX6390XS31D7+ from Maxim Integrated is a low-power microprocessor supervisory circuit with open-drain active-low reset output, factory-set 3.08V VCC reset threshold (±2.5% over -40°C to +125°C), 1200ms minimum VCC reset timeout, and 150ms minimum manual reset timeout. It operates from +1.0V to +5.5V supply and consumes only 3µA at +1.8V, used in battery-powered embedded controllers for reliable power-on reset and brownout protection.

For engineers reviewing the MAX6390XS31D7+ datasheet, MAX6390XS31D7+ pinout, MAX6390XS31D7+ application, or MAX6390XS31D7+ equivalent, key selection criteria include its dual-timing reset architecture (VCC vs. MR timeout), SC70-4 package footprint, guaranteed reset validity down to VCC = 1V, and compatibility with 1.8V–5.0V logic domains in space-constrained portable systems.

Technical Context

The MAX6390XS31D7+ integrates a precision voltage comparator monitoring VCC against a fixed 3.08V threshold and a separate manual reset input (MR) with internal 1.56kΩ pullup resistor. Its reset assertion logic combines asynchronous MR-triggered reset with timed deassertion: after MR release, reset remains active for 150ms (min), while VCC recovery triggers a longer 1200ms (min) timeout.

This dual-timing behavior distinguishes it from standard single-delay supervisors. The open-drain RESET output requires an external pullup and guarantees valid logic state down to VCC = 1V, enabling robust reset signaling even during deep brownout conditions in ultra-low-power applications.

Key Specifications

Pinout & Package

MAX6390XS31D7+ uses a 4-pin SC70 package (X4-1, 1.3mm × 1.1mm × 0.6mm), optimized for high-density PCB layouts in portable electronics.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6390XS31D7+, MAX6326TASD3+T simplifies design where manual reset is unnecessary, while TPS3808G33DBVR adds watchdog capability at the cost of losing independent MR timing - neither replicates the 1200ms/150ms dual-delay profile critical for coordinated power-user reset sequences.

Availability

MAX6390XS31D7+ is available at Aetrix Electronics and suitable for battery-powered medical sensors, industrial PLC I/O modules, automotive body control units, and smart home hub power sequencers requiring stable component supply and long-term lifecycle support.

Supply support for MAX6390XS31D7+ 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 industrial, automotive, and computing applications, emphasizing low power, high reliability, and small form factors.

The MAX6381–MAX6390 family delivers single/dual low-voltage µP reset circuits targeting space- and power-constrained embedded systems needing guaranteed reset behavior across extreme temperatures and supply conditions.

FAQ

What is the exact reset threshold voltage of MAX6390XS31D7+ and how stable is it over temperature?

The MAX6390XS31D7+ has a factory-set reset threshold of 3.08V with ±2.5% accuracy over the full operating temperature range of -40°C to +125°C. This stability is achieved through laser-trimmed internal references and low-tempco design, eliminating need for external calibration in industrial-grade applications. The MAX6390XS31D7+ maintains this tolerance without derating or additional compensation circuits.

Does MAX6390XS31D7+ support manual reset functionality, and what are its timing characteristics?

Yes, MAX6390XS31D7+ includes a dedicated MR (manual reset) input with internal 1.56kΩ pullup resistor. When MR is pulled low, reset asserts immediately and remains active for a guaranteed minimum of 150ms after MR returns high. This shorter timeout is independent of the 1200ms VCC reset timeout, enabling fast user-initiated recovery without disrupting power-up sequencing. The MAX6390XS31D7+ datasheet confirms this dual-timing behavior is specific to the MAX6390 variant.

What package type and pin count does MAX6390XS31D7+ use, and is it compatible with automated assembly?

MAX6390XS31D7+ uses a 4-pin SC70 package (package code X4-1), measuring 1.3mm × 1.1mm × 0.6mm with gull-wing leads. It is fully compatible with standard surface-mount reflow processes including lead-free soldering profiles. The SC70 footprint is widely supported in pick-and-place equipment and stencil design libraries, making MAX6390XS31D7+ suitable for high-volume automated manufacturing of compact portable electronics.

How does the open-drain RESET output of MAX6390XS31D7+ differ from push-pull alternatives, and what external components are required?

The MAX6390XS31D7+ features an open-drain active-low RESET output, requiring an external pullup resistor to the target logic rail (e.g., 3.3V or 1.8V). This enables wired-OR connection with other reset sources and level translation across voltage domains. Unlike push-pull outputs, it cannot actively drive high - only sink current when asserted. No other external components are needed beyond the pullup; the MAX6390XS31D7+ integrates all timing, threshold, and MR functions internally.

Can MAX6390XS31D7+ operate reliably at very low supply voltages, and what is its minimum functional VCC?

Yes, MAX6390XS31D7+ guarantees correct reset output logic state down to VCC = 1.0V, per its absolute maximum ratings and electrical characteristics table. This ensures deterministic behavior during deep brownout conditions where supply may collapse to near 1V before recovery. The device remains fully functional across its specified 1.0V to 5.5V operating range, with supply current scaling linearly (3µA at 1.8V, 6µA at 3.6V). This capability is intrinsic to the MAX6390XS31D7+ design and validated across temperature.