Analog Devices Inc./Maxim Integrated MAX6389LT29D3+T

Overview

MAX6389LT29D3+T from Maxim Integrated is a low-power microprocessor supervisory circuit with open-drain active-low reset output, factory-set 2.93V reset threshold (±2.5% over -40°C to +125°C), 140ms minimum reset timeout, and auxiliary RESET IN input for dual-voltage monitoring. It operates from 1.0V to 5.5V supply and consumes only 3μA at 1.8V, enabling reliable power-up/brownout protection in space-constrained battery-powered systems.

For engineers reviewing the MAX6389LT29D3+T datasheet, MAX6389LT29D3+T pinout, MAX6389LT29D3+T application, or MAX6389LT29D3+T equivalent, key selection considerations include its open-drain reset architecture requiring external pullup, dual-supply monitoring capability via RESET IN, guaranteed reset validity down to VCC = 1V, and AEC-Q100-qualified automotive variants.

Technical Context

The MAX6389LT29D3+T integrates a precision voltage comparator monitoring VCC against a 2.93V threshold and a second comparator referencing an internal 1.27V bandgap to monitor external voltages via the RESET IN pin. Its reset assertion logic triggers when either monitored voltage falls below its respective threshold, with independent timing control ensuring deterministic deassertion after recovery.

It features a dedicated open-drain RESET output with 0.3V VOL at 80µA sink current (VCC ≥ 1.0V), internal 50nA RESET IN leakage, and immunity to negative-going VCC transients up to 35µs duration at 100mV overdrive - critical for noisy industrial and automotive power rails.

Key Specifications

Pinout & Package

MAX6389LT29D3+T is housed in a 4-pin SC70 package (outline 21-0098, land pattern 90-0187) with 0.65mm pitch and RoHS-compliant lead-free finish. The compact 2.0mm × 2.1mm footprint supports 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 MAX6389LT29D3+T, MAX6389XS29D3+T offers identical performance in the same package form factor, while TLV809E29DBZR reduces cost and complexity at the expense of dual-supply monitoring - making MAX6389LT29D3+T optimal for systems requiring independent validation of multiple rails.

Availability

MAX6389LT29D3+T is available at Aetrix Electronics and suitable for industrial PLCs, automotive body controllers, portable medical sensors, battery-powered smart meters, and dual-voltage embedded systems requiring stable component supply with AEC-Q100 qualification support.

Supply support for MAX6389LT29D3+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 demanding industrial, automotive, and computing applications, with emphasis on low-power, high-reliability solutions.

The MAX6381–MAX6390 family delivers ultra-low-power microprocessor supervisory circuits optimized for battery-critical and thermally harsh environments, featuring factory-trimmed thresholds, dual-supply monitoring, and AEC-Q100 qualification paths.

FAQ

What is the exact reset threshold voltage of MAX6389LT29D3+T and how stable is it over temperature?

The MAX6389LT29D3+T has a factory-set reset threshold of 2.93V with ±2.5% tolerance over the full -40°C to +125°C operating range. This stability is achieved through laser-trimming during production and verified by design per the datasheet's Electrical Characteristics table, ensuring consistent brownout detection across automotive and industrial thermal profiles without external calibration.

Does MAX6389LT29D3+T support monitoring two independent power supplies?

Yes, MAX6389LT29D3+T supports dual-supply monitoring: VCC is monitored against its 2.93V threshold, while the RESET IN pin compares an external voltage to an internal 1.27V reference. When either voltage falls below its respective threshold, the open-drain RESET output asserts - enabling coordinated reset of systems with separate core and I/O rails.

What is the required external pullup resistor value for the open-drain RESET output of MAX6389LT29D3+T?

The MAX6389LT29D3+T RESET output is open-drain and requires an external pullup resistor to the host logic rail (e.g., 3.3V or 5V). A typical value is 10kΩ to 100kΩ; lower values improve rise time but increase static current, while higher values reduce current but may slow edge transitions. The datasheet specifies VOL ≤ 0.3V at 80µA sink, confirming compatibility with standard CMOS inputs.

Can MAX6389LT29D3+T operate reliably when VCC drops below 1.8V?

Yes, MAX6389LT29D3+T guarantees valid reset output behavior down to VCC = 1.0V, with supply current dropping to 3μA at 1.8V and remaining functional at lower voltages. Its reset assertion remains accurate even during deep brownout, and the open-drain output maintains defined logic states - critical for orderly shutdown in battery-depleted scenarios.

Is MAX6389LT29D3+T qualified for automotive applications?

MAX6389LT29D3+T itself is not automotive-qualified, but the MAX6389 family includes /V suffix variants (e.g., MAX6389XS29D3/V+T) that are AEC-Q100 qualified. The "+T" suffix indicates RoHS-compliant packaging, while automotive qualification requires explicit /V marking in the part number - confirmed in the Ordering Information table on page 8 of the datasheet.