Analog Devices Inc./Maxim Integrated MAX6389LT28D2+T

Overview

MAX6389LT28D2+T from Maxim Integrated is a low-power microprocessor supervisory circuit with open-drain active-low reset output, factory-set 2.80V VCC reset threshold (±2.5% over −40°C to +125°C), 20ms 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, serving in battery-powered instrumentation and embedded controllers requiring reliable power-up/brownout detection.

For engineers reviewing the MAX6389LT28D2+T datasheet, MAX6389LT28D2+T pinout, MAX6389LT28D2+T application, or MAX6389LT28D2+T equivalent, key selection criteria include its 2.80V reset threshold accuracy, 20ms VCC reset timeout, open-drain output requiring external pullup, RESET IN comparator referenced to +1.27V, and guaranteed valid reset state down to VCC = 1V.

Technical Context

The MAX6389LT28D2+T integrates a precision voltage comparator for VCC monitoring and a separate high-impedance RESET IN comparator referenced to an internal +1.27V bandgap. Reset asserts when either VCC falls below 2.80V or RESET IN drops below its threshold (set via external resistor divider), with independent timing control ensuring deterministic deassertion after recovery.

Its open-drain RESET output supports wired-OR configurations and level-shifting across voltage domains, while the RESET IN path features 4.5µs propagation delay (−40°C to +125°C) and ±50nA input leakage-enabling accurate secondary supply monitoring without loading sensitive nodes.

Key Specifications

Pinout & Package

MAX6389LT28D2+T is housed in a RoHS-compliant 4-pin SC70 package (outline 21-0098, land pattern 90-0187), measuring 2.0mm × 2.1mm × 0.95mm, optimized for space-constrained portable designs.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6389LT28D2+T, MAX6389XS28D2+T saves PCB area but sacrifices dual-supply supervision, while TLV809E28DBZR offers lower unit cost at the expense of higher current draw, missing RESET IN, and reduced environmental robustness.

Availability

MAX6389LT28D2+T is available at Aetrix Electronics and suitable for industrial sensor nodes, automotive body control modules, medical wearables, and POS terminals requiring stable component supply with guaranteed long-term availability.

Supply support for MAX6389LT28D2+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.

The MAX6381–MAX6390 family delivers ultra-low-power, high-accuracy reset supervision for battery-operated and safety-critical systems, emphasizing thermal stability, glitch immunity, and dual-rail monitoring capability.

FAQ

What is the exact reset threshold voltage of MAX6389LT28D2+T and how stable is it over temperature?

The MAX6389LT28D2+T has a factory-trimmed nominal VCC reset threshold of 2.80V, with ±2.5% accuracy guaranteed over the full −40°C to +125°C operating range. Its tempco is 60ppm/°C, resulting in maximum deviation of ±35mV across temperature - sufficient for robust brownout detection in automotive and industrial environments where MAX6389LT28D2+T is commonly deployed.

Does MAX6389LT28D2+T require an external pullup resistor on the RESET pin?

Yes, MAX6389LT28D2+T features an open-drain active-low RESET output and requires an external pullup resistor to the target logic voltage (e.g., 3.3V or 5V). The datasheet specifies a maximum sink current of 3.2mA at VCC ≥ 4.5V, so a 10kΩ pullup is typical for standard CMOS loads - ensuring proper reset assertion without excessive current draw when MAX6389LT28D2+T is used in low-power systems.

Can MAX6389LT28D2+T monitor two different supply voltages simultaneously?

Yes, MAX6389LT28D2+T provides dual-supply monitoring via its dedicated RESET IN pin, which compares an external voltage to an internal +1.27V reference. When combined with its primary VCC monitor set to 2.80V, MAX6389LT28D2+T independently supervises two rails - for example, a 3.3V I/O supply (VCC) and a 1.2V core supply (via RESET IN divider) - asserting reset if either falls out of specification.

What is the minimum supply voltage at which MAX6389LT28D2+T guarantees correct reset output behavior?

MAX6389LT28D2+T guarantees valid RESET output logic states down to VCC = 1.0V, meaning the open-drain output remains correctly asserted or deasserted even as the supply collapses. This ensures deterministic microprocessor behavior during deep brownout events - a critical feature absent in many competing supervisors, making MAX6389LT28D2+T especially valuable in battery-backed systems where MAX6389LT28D2+T must operate through full discharge cycles.

Is MAX6389LT28D2+T qualified for automotive applications?

MAX6389LT28D2+T itself is not automotive-qualified; however, the identical function is available in automotive-grade versions such as MAX6389LT28D2/V+T (with /V suffix), which meets AEC-Q100 Grade 1 requirements (−40°C to +125°C) and undergoes additional stress testing. For production automotive designs, engineers must specify the /V variant - MAX6389LT28D2+T is intended for industrial and commercial applications where AEC-Q100 is not mandated.