Analog Devices Inc./Maxim Integrated MAX6389XS22D2+T

Overview

MAX6389XS22D2+T from Maxim Integrated is a low-power microprocessor supervisory circuit with open-drain active-low reset output, factory-set 2.19V 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, enabling use in battery-powered systems requiring reliable power-on reset and brownout protection.

For engineers reviewing the MAX6389XS22D2+T datasheet, MAX6389XS22D2+T pinout, MAX6389XS22D2+T application, or MAX6389XS22D2+T equivalent, key selection criteria include its 2.19V reset threshold accuracy, 20ms timeout timing, open-drain output requiring external pullup, RESET IN comparator referenced to 1.27V, and 4-pin SC70 package compatibility with space-constrained embedded designs.

Technical Context

The MAX6389XS22D2+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 2.19V or RESET IN drops below 1.27V, with propagation delay under 5µs for RESET IN transitions.

Its open-drain RESET output supports flexible logic-level interfacing across mixed-voltage systems, and guaranteed valid operation down to VCC = 1V ensures robust reset assertion during deep brownout conditions without requiring external biasing circuitry.

Key Specifications

Pinout & Package

MAX6389XS22D2+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 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 MAX6389XS22D2+T, the LT22D2+T variant offers identical functionality in a thermally superior μDFN package but occupies more PCB area, while TPS3808G125DBVR trades dual-supply flexibility and open-drain interoperability for simpler integration in single-rail 2.5V systems.

Availability

MAX6389XS22D2+T is available at Aetrix Electronics and suitable for battery-powered IoT sensors, automotive body control modules, industrial PLC I/O cards, and medical wearable vital sign monitors requiring stable component supply with guaranteed long-term continuity.

Supply support for MAX6389XS22D2+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 demanding industrial, automotive, and computing applications.

The MAX6381–MAX6390 family delivers ultra-low-power, high-accuracy reset supervision for microprocessor-based systems where reliability under brownout, transient, and wide-temperature conditions is critical.

FAQ

What is the exact reset threshold voltage of MAX6389XS22D2+T and how stable is it over temperature?

The MAX6389XS22D2+T has a factory-set nominal VCC reset threshold of 2.19V, with guaranteed accuracy of ±2.5% over the full –40°C to +125°C operating range. Its temperature coefficient is 60ppm/°C, meaning threshold drift is limited to ±0.013V across the entire temperature span - sufficient to maintain timing margins in automotive and industrial applications without recalibration.

Does MAX6389XS22D2+T require an external pullup resistor on the RESET pin, and what value is recommended?

Yes, MAX6389XS22D2+T features an open-drain active-low RESET output and requires an external pullup resistor. A 4.7kΩ to 10kΩ resistor to the target logic supply (e.g., 3.3V or 5V) is recommended: it ensures fast rise time (<100ns) while limiting sink current to <1mA during reset assertion, staying well within the 3.2mA absolute maximum rating at VCC ≥ 4.5V.

Can MAX6389XS22D2+T monitor two independent power rails simultaneously, and how is the second rail configured?

Yes, MAX6389XS22D2+T supports dual-rail supervision: VCC is monitored directly, and a second rail is monitored via the RESET IN pin. To configure the second threshold, connect RESET IN to the center tap of a resistor divider between the secondary rail and ground. With an internal 1.27V reference, the divider sets the trip point using R1 = R2 × ((V_TH/1.27V) – 1); typical R2 values are 100kΩ to 1MΩ due to <50nA input leakage.

What is the minimum supply voltage at which MAX6389XS22D2+T guarantees correct RESET output logic state?

MAX6389XS22D2+T guarantees valid RESET output logic state down to VCC = 1.0V. Below this, the internal comparators and timer may become indeterminate. This feature ensures reliable reset assertion during deep brownout events common in battery-depleted or cold-start conditions, eliminating the need for external undervoltage lockout circuitry.

Is MAX6389XS22D2+T qualified for automotive applications, and what packaging indicates this qualification?

MAX6389XS22D2+T itself is not automotive-qualified; it carries the "+T" RoHS-compliant suffix but lacks the "/V" automotive qualification marker. For AEC-Q100 Grade 2 (–40°C to +105°C) compliance, select variants such as MAX6389XS22D2/V+T - the "/V" suffix explicitly denotes automotive qualification per the manufacturer's ordering information table.