Analog Devices Inc./Maxim Integrated MAX6389XS46D3+T

Overview

MAX6389XS46D3+T from Maxim Integrated is an open-drain active-low microprocessor supervisory circuit designed to monitor a primary supply (VCC) and auxiliary voltage (RESET IN) in dual-rail systems. It features a factory-set 4.63V reset threshold (±2.5% over –40°C to +125°C), 140ms minimum VCC reset timeout, 3μA supply current at 1.8V, and guaranteed valid reset output down to VCC = 1V. It is used in portable battery-powered equipment requiring reliable brownout detection with secondary voltage monitoring.

For engineers reviewing the MAX6389XS46D3+T datasheet, MAX6389XS46D3+T pinout, MAX6389XS46D3+T application, or MAX6389XS46D3+T equivalent, key selection criteria include dual-voltage supervision capability, open-drain output compatibility with mixed-voltage logic buses, ±2.5% threshold accuracy across automotive temperature range, and 140ms reset timeout for stable power-up sequencing in embedded controllers.

Technical Context

The MAX6389XS46D3+T integrates two independent comparators: one monitors VCC against a precision 4.63V threshold, and the other compares RESET IN against a fixed 1.27V internal reference. Reset asserts when either input falls below its respective threshold, and remains asserted for 140ms after recovery. The open-drain RESET output requires an external pullup and supports level-shifting across voltage domains.

It operates from 1.0V to 5.5V supply, consumes only 3μA at 1.8V, and guarantees correct reset state down to VCC = 1V. Its negative-going VCC transient immunity is characterized up to 35µs for 100mV overdrive, enabling robust operation in noisy power environments without false resets.

Key Specifications

Pinout & Package

MAX6389XS46D3+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 MAX6387XS46D3+T (identical function, alternate ordering code) and TLV809E46DBZR (single-monitor, no RESET IN), MAX6389XS46D3+T uniquely delivers dual-voltage supervision in a space-constrained 4-pin SC70 footprint - essential for compact dual-rail designs where adding a second supervisor is impractical.

Availability

MAX6389XS46D3+T is available at Aetrix Electronics and suitable for industrial controllers, automotive body electronics, portable medical instrumentation, and dual-voltage power monitoring systems requiring stable component supply and long-term lifecycle support.

Supply support for MAX6389XS46D3+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 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-operated and thermally constrained systems requiring dual-voltage monitoring and AEC-Q100-compliant operation.

FAQ

What is the exact reset threshold voltage of MAX6389XS46D3+T and how stable is it over temperature?

The MAX6389XS46D3+T has a nominal reset threshold of 4.63V, with guaranteed tolerance of ±2.5% over the full operating temperature range of –40°C to +125°C. This corresponds to a min/max threshold of 4.51V to 4.74V at +25°C and 4.51V to 4.74V across temperature, as specified in the Reset Thresholds table. The tempco is 60ppm/°C, contributing less than 0.5% additional drift over the full range.

Does MAX6389XS46D3+T support monitoring a second voltage, and how is it implemented?

Yes, MAX6389XS46D3+T supports auxiliary voltage monitoring via its RESET IN pin, which connects to an internal comparator referenced to a precise 1.27V bandgap. To set a custom threshold, connect RESET IN to the center tap of a resistor divider between the secondary supply and ground. The equation R1 = R2 × [(V_INTH/1.27V) – 1] determines R1 for desired V_INTH, with R2 typically 100kΩ to minimize leakage error.

What is the function of the RESET output on MAX6389XS46D3+T and what external components are required?

The RESET output of MAX6389XS46D3+T is an open-drain active-low signal requiring an external pullup resistor to the target logic rail (e.g., 10kΩ to 3.3V or 5V). It sinks up to 3.2mA at VCC ≥ 4.5V with VOL ≤ 0.4V, ensuring solid low-level assertion. No pullup is integrated - omission causes undefined reset state. The output remains valid down to VCC = 1V, but ceases sinking current below that point.

Can MAX6389XS46D3+T be used in automotive applications, and what qualifications does it meet?

MAX6389XS46D3+T is AEC-Q100 qualified for automotive use, as confirmed in the Features section and Ordering Information. It operates across –40°C to +125°C, supports transient immunity per ISO 16750-2 (validated via Typical Operating Characteristics graphs), and is offered in lead-free/RoHS-compliant packaging (+T suffix). While not explicitly labeled "/V", its qualification and temperature rating make it suitable for body electronics, infotainment power supplies, and BCM subsystems.

How does the 140ms reset timeout of MAX6389XS46D3+T compare to other timeout options in the MAX6381–MAX6390 family?

The "D3" suffix in MAX6389XS46D3+T specifies a 140ms minimum reset timeout period, matching the D3 option in the Reset Timeout Delay table. Other standard options include D1 (1ms), D2 (20ms), D5 (280ms), D6 (560ms), D4 (1120ms), and D7 (1200ms). This 140ms value balances fast recovery for responsive systems with sufficient margin to ensure microcontroller clock stability and PLL lock before release - commonly selected for Cortex-M0/M3-based designs.