Analog Devices Inc./Maxim Integrated MAX6389XS26D3+T

Overview

MAX6389XS26D3+T from Maxim Integrated is a low-power microprocessor supervisory circuit with open-drain active-low reset output, factory-set 2.63V VCC reset threshold (±2.5% over -40°C to +125°C), 140ms minimum reset timeout, and auxiliary RESET IN input for dual-voltage monitoring in battery-powered embedded systems.

For engineers reviewing the MAX6389XS26D3+T datasheet, MAX6389XS26D3+T pinout, MAX6389XS26D3+T application, or MAX6389XS26D3+T equivalent, key selection considerations include its 3μA supply current at 1.8V, guaranteed reset validity down to VCC = 1V, ±60ppm/°C reset threshold tempco, and compatibility with dual-rail power domains requiring independent voltage supervision.

Technical Context

The MAX6389XS26D3+T implements a precision bandgap-based reset comparator for VCC monitoring and a separate +1.27V reference comparator for the RESET IN pin, enabling independent supervision of two voltage rails. Its internal timer guarantees a minimum 140ms reset assertion after VCC recovery or RESET IN deassertion.

It features an open-drain RESET output requiring an external pullup resistor, supports VCC operation from 1.0V to 5.5V, and maintains valid logic states across the full industrial temperature range (-40°C to +125°C) with negative-going transient immunity up to 35µs at 100mV overdrive.

Key Specifications

Pinout & Package

MAX6389XS26D3+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, with thermal resistance θ_JA = 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 MAX6387XS26D3+T, the MAX6389XS26D3+T's open-drain output enables shared reset buses and flexible voltage translation, while versus TLV809K26DBZR, its integrated RESET IN and tighter ±2.5% threshold accuracy support robust dual-rail systems in demanding industrial settings.

Availability

MAX6389XS26D3+T is available at Aetrix Electronics and suitable for battery-powered medical devices, automotive body electronics, industrial PLC I/O cards, and smart energy meters requiring stable component supply with long-term lifecycle assurance.

Supply support for MAX6389XS26D3+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, mixed-signal, and power management ICs for industrial, automotive, and computing applications.

The MAX6381–MAX6390 family delivers ultra-low-power, high-accuracy reset supervision for microprocessor-based systems operating under constrained power budgets and harsh environmental conditions.

FAQ

What is the exact reset threshold voltage of MAX6389XS26D3+T and how stable is it over temperature?

The MAX6389XS26D3+T has a factory-set nominal VCC reset threshold of 2.63V, with guaranteed tolerance of ±2.5% across the full operating temperature range of -40°C to +125°C. Its temperature coefficient is ±60ppm/°C, meaning the threshold drifts less than ±0.016V over the entire range - ensuring consistent brownout detection without recalibration in automotive or industrial deployments.

Does MAX6389XS26D3+T require an external pullup resistor on the RESET pin?

Yes, MAX6389XS26D3+T features an open-drain active-low RESET output and requires an external pullup resistor to define the high-state voltage and provide current sourcing capability. Typical values range from 10kΩ to 100kΩ depending on bus capacitance and rise-time requirements; the resistor must connect between RESET and the target logic rail (e.g., 3.3V or 5V).

Can MAX6389XS26D3+T monitor two different voltage rails simultaneously?

Yes, MAX6389XS26D3+T supports dual-rail supervision: VCC is monitored against its fixed 2.63V threshold, while the RESET IN pin compares an external voltage (via resistor divider) against an internal +1.27V reference. Reset asserts if either rail falls below its respective threshold - enabling coordinated reset for core and I/O supplies in SoC-based systems.

What is the minimum VCC voltage at which MAX6389XS26D3+T guarantees correct RESET output behavior?

MAX6389XS26D3+T guarantees valid RESET output logic states down to VCC = 1.0V. Below this, the internal circuitry cannot maintain defined output levels. This feature ensures reliable reset assertion during deep brownout events common in battery-depleted or unregulated power scenarios - a key requirement for fail-safe embedded control.

How does the 140ms reset timeout of MAX6389XS26D3+T benefit system reliability?

The 140ms minimum reset timeout of MAX6389XS26D3+T ensures the microprocessor remains held in reset long enough for all power rails to stabilize, clocks to lock, and decoupling capacitors to charge fully after power-up or recovery from brownout. This prevents erratic code execution, memory corruption, or peripheral initialization failures - especially critical in safety-critical or data-logging applications.