Analog Devices Inc./Maxim Integrated MAX6387XS28D2+

Overview

MAX6387XS28D2+ from Maxim Integrated is a dual-voltage microprocessor supervisory circuit with active-low push-pull reset output, factory-set 2.80V 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 consumes only 3µA at +1.8V and guarantees valid reset state down to VCC = 1V, used in portable battery-powered equipment and dual-rail embedded systems.

For engineers reviewing the MAX6387XS28D2+ datasheet, MAX6387XS28D2+ pinout, MAX6387XS28D2+ application, or MAX6387XS28D2+ equivalent, this page delivers verified functional identity, exact SC70-4 package mapping, confirmed dual-monitoring capability, reset timing accuracy, and real-world selection guidance against comparable supervisory ICs.

Technical Context

The MAX6387XS28D2+ integrates two independent voltage comparators: one monitors VCC against a fixed 2.80V threshold, the other compares an external voltage applied to RESET IN against an internal +1.27V reference. Reset asserts if either comparator detects an under-voltage condition.

Its internal timer ensures a guaranteed minimum 140ms reset assertion after VCC or RESET IN recovers above their respective thresholds. The push-pull active-low RESET output drives directly without external pull-up, and operates reliably across the full −40°C to +125°C industrial temperature range.

Key Specifications

Pinout & Package

MAX6387XS28D2+ is housed in a lead-free 4-pin SC70 package (X4-1), measuring 1.0mm × 1.0mm × 0.5mm, optimized for space-constrained portable designs.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6387XS28D2+, the µDFN variant offers superior thermal performance in dense layouts, while the TPS3808G125DBVR lacks dual-supply capability and requires external biasing-making MAX6387XS28D2+ the only option that delivers compact size, dual-rail supervision, and push-pull drive in one device.

Availability

MAX6387XS28D2+ is available at Aetrix Electronics and suitable for portable medical sensors, industrial PLC I/O modules, automotive body control units, and smart energy meters requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MAX6387XS28D2+ 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 power management ICs for demanding industrial, automotive, and computing applications.

The MAX6381–MAX6390 family was engineered specifically for low-power, dual-rail microprocessor supervision in space- and energy-constrained systems-delivering factory-trimmed accuracy, ultra-low ICC, and auxiliary voltage monitoring in miniature packages.

FAQ

What is the exact reset threshold voltage of MAX6387XS28D2+ and how stable is it over temperature?

The MAX6387XS28D2+ has a factory-set VCC reset threshold of 2.80V, with ±2.5% tolerance guaranteed over the full −40°C to +125°C operating range. This stability is achieved via laser-trimmed on-chip resistors and a bandgap reference, eliminating the need for external calibration. The MAX6387XS28D2+ maintains this accuracy without drift, making it suitable for mission-critical brownout protection in automotive and industrial settings.

Does MAX6387XS28D2+ support monitoring of a second voltage rail, and how is it implemented?

Yes, MAX6387XS28D2+ includes a dedicated RESET IN pin that connects to an internal +1.27V comparator. To monitor a second rail (e.g., 1.8V or 3.3V), apply the voltage through a resistor divider to RESET IN so that the divided voltage equals 1.27V at the target trip point. The MAX6387XS28D2+ asserts reset if either VCC falls below 2.80V or the voltage at RESET IN drops below +1.27V-enabling true dual-supply supervision in a single 4-pin device.

What is the function of the RESET output on MAX6387XS28D2+, and does it require an external pull-up resistor?

The RESET output of MAX6387XS28D2+ is an active-low push-pull driver, meaning it actively pulls low during reset assertion and actively drives high when deasserted. Because it is not open-drain, no external pull-up resistor is required-simplifying design and reducing component count. This feature ensures fast, clean transitions and full rail-to-rail swing, which is essential for reliable µP reset signaling in noise-prone environments.

What is the minimum VCC voltage at which MAX6387XS28D2+ guarantees correct RESET logic state?

MAX6387XS28D2+ guarantees valid RESET output logic state down to VCC = 1.0V. Below this level, the internal circuitry may not operate predictably, but above 1.0V-including during brownout conditions-the device ensures RESET remains asserted until both monitored voltages recover and the 140ms timeout expires. This specification is critical for fail-safe operation in battery-powered devices where supply voltage decays gradually.

Can MAX6387XS28D2+ replace older Maxim supervisors like MAX809 or MAX6326 in existing designs?

MAX6387XS28D2+ is not pin-compatible with MAX809 or MAX6326 due to different pin count (4-pin SC70 vs. 3-pin SOT23) and added RESET IN functionality. However, it is explicitly listed in the datasheet as pin-compatible with MAX6384–MAX6390 series in the same SC70-4 package. For drop-in replacement of legacy 3-pin parts, redesign is required-but the MAX6387XS28D2+ offers superior features including dual-rail monitoring and tighter threshold accuracy.