Analog Devices Inc./Maxim Integrated MAX6389XS26D3+

Overview

MAX6389XS26D3+ 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. It consumes only 3μA at +1.8V and guarantees valid reset state down to VCC = 1V, used in battery-powered instrumentation and industrial controllers requiring reliable brownout detection.

For engineers reviewing the MAX6389XS26D3+ datasheet, MAX6389XS26D3+ pinout, MAX6389XS26D3+ application, or MAX6389XS26D3+ equivalent, key selection criteria include its 2.63V threshold accuracy, 140ms timeout, open-drain output compatibility with mixed-voltage systems, RESET IN comparator referenced to +1.27V, and 4-pin SC70 package footprint.

Technical Context

The MAX6389XS26D3+ integrates a precision voltage comparator monitoring VCC against a fixed 2.63V threshold and a separate high-impedance RESET IN input compared to an internal +1.27V reference. Reset assertion occurs when either voltage falls below its respective threshold, with independent timing control.

Its open-drain RESET output requires an external pullup and supports level-shifting across voltage domains; the RESET IN path includes 50nA max leakage and 4.5µs propagation delay over temperature, enabling accurate resistor-divider–based secondary supply monitoring without additional components.

Key Specifications

Pinout & Package

MAX6389XS26D3+ is housed in a RoHS-compliant 4-pin SC70 package (package code X4+1), measuring 2.0mm × 2.1mm × 0.95mm, with 0.65mm pin pitch and exposed pad optional per land pattern 90-0187.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6389XS26D3+, MAX6387XS26D3+ offers identical electrical behavior in a larger package, while TPS3808G33DBVR trades dual-rail flexibility and low-threshold capability for simplified single-rail integration and higher drive strength.

Availability

MAX6389XS26D3+ is available at Aetrix Electronics and suitable for industrial PLC I/O modules, battery-powered data loggers, and automotive body control units requiring stable component supply with AEC-Q100–compatible variants.

Supply support for MAX6389XS26D3+ 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 power efficiency and reliability.

The MAX6381–MAX6390 product line delivers ultra-low-power, factory-trimmed reset supervisors targeting space-constrained, battery-operated, and thermally demanding systems requiring dual-voltage monitoring and guaranteed brownout protection.

FAQ

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

The MAX6389XS26D3+ has a nominal VCC reset threshold of 2.63V, with guaranteed accuracy of ±2.5% across the full operating temperature range of -40°C to +125°C. This stability is achieved via factory laser trimming and BiCMOS process design, making MAX6389XS26D3+ suitable for automotive and industrial applications where thermal drift must not compromise reset timing integrity.

Does MAX6389XS26D3+ support monitoring of a second voltage rail, and how is it implemented?

Yes, MAX6389XS26D3+ includes a dedicated RESET IN pin compared to an internal +1.27V reference. To monitor a second voltage (e.g., 5V or 12V), connect a resistor divider between that rail and GND, feeding the midpoint to RESET IN. The threshold is calculated as V_TH = 1.27V × (R1/R2 + 1), where R1 is the upper resistor and R2 the lower. MAX6389XS26D3+ asserts reset if either VCC or the divided RESET IN voltage falls below its respective threshold.

What is the function of the open-drain RESET output in MAX6389XS26D3+, and what external component is required?

The open-drain RESET output of MAX6389XS26D3+ provides active-low reset signaling with inherent voltage-level translation capability. It requires an external pullup resistor to the target logic rail (e.g., 1.8V or 3.3V). Typical values range from 4.7kΩ to 10kΩ; the resistor ensures proper logic high when reset is inactive and allows multiple MAX6389XS26D3+ outputs to share a common reset bus via wired-OR configuration.

How does MAX6389XS26D3+ behave during severe supply droop - down to what VCC level does it guarantee correct reset assertion?

MAX6389XS26D3+ guarantees correct reset output logic state (active-low asserted) down to VCC = 1.0V. Below this, the internal comparators and timer may become indeterminate. This feature ensures deterministic microprocessor behavior during deep brownout events, preventing execution of corrupted code - a critical requirement in safety-critical and battery-depleted operation where VCC can decay well below nominal levels before shutdown.

Is MAX6389XS26D3+ pin-compatible with other members of the MAX6381–MAX6390 family, and which packages share the same pinout?

MAX6389XS26D3+ uses a 4-pin SC70 package (pinout: VCC, RESET, GND, RESET IN) and is pin-compatible with other 4-pin SC70 variants in the family, including MAX6384XSxxDx+, MAX6385XSxxDx+, MAX6386XSxxDx+, MAX6387XSxxDx+, MAX6388XSxxDx+, and MAX6390XSxxDx+. It is not pin-compatible with 3-pin SC70 or 6-pin µDFN versions due to differing pin count and assignment - always verify land pattern against Maxim's document 21-0098 for MAX6389XS26D3+.