Analog Devices Inc./Maxim Integrated MAX6387XS29D3-T

Overview

MAX6387XS29D3-T from Maxim Integrated is a dual-voltage microprocessor supervisory circuit with active-low push-pull reset output, factory-set 2.93V 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 battery-powered instrumentation and dual-rail embedded systems requiring reliable power-up sequencing and brownout protection.

For engineers reviewing the MAX6387XS29D3-T datasheet, MAX6387XS29D3-T pinout, MAX6387XS29D3-T application, or MAX6387XS29D3-T equivalent, key selection criteria include its 2.93V fixed VCC threshold, 140ms timeout, 4-pin SC70 package, auxiliary voltage monitoring capability, and guaranteed operation down to 1V supply - critical for low-power portable and automotive-qualified designs.

Technical Context

The MAX6387XS29D3-T integrates two independent voltage comparators: one monitors VCC against a precision ±2.5% 2.93V internal reference, the other compares an external voltage applied to RESET IN against a stable +1.27V internal reference. Reset asserts when either comparator trips, and remains asserted for a guaranteed minimum 140ms after recovery.

Its push-pull active-low RESET output drives directly without external pullup, supports sink currents up to 3.2mA at VCC ≥ 4.5V (VOL ≤ 0.4V), and maintains logic validity down to VCC = 1V. The device uses BiCMOS process technology and operates across -40°C to +125°C with negative-going transient immunity validated per typical operating characteristics.

Key Specifications

Pinout & Package

MAX6387XS29D3-T is housed in a RoHS-compliant 4-pin SC70 package (outline 21-0098, land pattern 90-0187), measuring 1.25mm × 1.65mm × 0.95mm, with 0.65mm pin pitch and thermal resistance θJA = 322.6°C/W on multilayer board.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6387XS29D3-T, MAX6387LT29D3-T offers identical supervision functionality in a thermally superior but physically larger package, while TPS3808G33DBVR provides a single-rail alternative with different threshold and no auxiliary input - neither is pin-compatible, and both require schematic and layout changes.

Availability

MAX6387XS29D3-T is available at Aetrix Electronics and suitable for battery-powered instrumentation, dual-rail microcontroller systems, and automotive body control modules requiring stable component supply, long-term lifecycle support, and AEC-Q100–aligned reliability.

Supply support for MAX6387XS29D3-T 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, with emphasis on low-power, high-reliability solutions.

The MAX6381–MAX6390 family delivers ultra-low-power, dual-voltage microprocessor supervisory circuits optimized for portable, automotive, and harsh-environment embedded systems demanding guaranteed reset behavior across wide temperature and supply ranges.

FAQ

What is the exact reset threshold voltage of MAX6387XS29D3-T and how stable is it over temperature?

The MAX6387XS29D3-T has a factory-set nominal VCC reset threshold of 2.93V, with guaranteed tolerance of ±2.5% over the full operating temperature range of -40°C to +125°C. This stability is achieved through laser-trimmed references and BiCMOS process design, ensuring consistent brownout detection without external calibration - critical for unattended field-deployed equipment where voltage margins are tight.

Does MAX6387XS29D3-T support monitoring of a second voltage rail, and how is it implemented?

Yes, MAX6387XS29D3-T includes a dedicated RESET IN input that compares an external voltage to an internal +1.27V reference. To monitor a second rail (e.g., 3.3V or 5V), connect it to RESET IN through a resistor divider - the threshold is set by R1/R2 ratio per V_INTH = 1.27V × (R1/R2 + 1). This eliminates need for a second supervisor IC in dual-supply systems like microcontrollers with separate core/I/O domains.

What is the reset timeout duration of MAX6387XS29D3-T, and is it guaranteed minimum or typical?

The MAX6387XS29D3-T provides a guaranteed minimum reset timeout period of 140ms after VCC or RESET IN recovers above their respective thresholds. This is not a typical value - it is production-tested and specified in the Electrical Characteristics table as "min" under t_RP for suffix D3. The actual timeout may be longer (up to 280ms per datasheet), ensuring robust reset hold time even under worst-case process/voltage/temperature corners.

Can MAX6387XS29D3-T operate reliably at very low supply voltages, and what is the lower limit?

Yes, MAX6387XS29D3-T guarantees correct RESET output logic state down to VCC = 1.0V - meaning it continues asserting or deasserting reset with defined voltage levels (e.g., VOL ≤ 0.3V when sinking 80µA) even as supply collapses. This ensures safe shutdown sequencing in battery-powered systems where VCC decays slowly, preventing partial execution or memory corruption during power-down.

Is MAX6387XS29D3-T pin-compatible with legacy Maxim reset ICs like MAX809 or MAX6326?

No, MAX6387XS29D3-T is not pin-compatible with MAX809/MAX6326 due to its 4-pin SC70 configuration (VCC, RESET, RESET IN, GND) versus the 3-pin SC70 layout of those legacy parts (VCC, RESET, GND). While functionally similar and listed as "pin compatible" in the datasheet's Features section, that statement refers to same-package *footprint families* (e.g., MAX6384–MAX6390 share 4-pin SC70), not cross-family compatibility - board redesign is required for replacement.