Analog Devices Inc./Maxim Integrated MAX6389XS16D3+

Overview

MAX6389XS16D3+ from Maxim Integrated is a low-power, open-drain active-low microprocessor supervisory circuit with factory-set 1.58V reset threshold, 140ms minimum reset timeout, auxiliary RESET IN input for dual-voltage monitoring, and operation down to VCC = 1.0V. It consumes only 3µA at +1.8V and supports industrial temperature range (–40°C to +125°C), used in portable battery-powered equipment and dual-voltage systems requiring reliable power-on reset.

For engineers reviewing the MAX6389XS16D3+ datasheet, MAX6389XS16D3+ pinout, MAX6389XS16D3+ application, or MAX6389XS16D3+ equivalent, key selection factors include its open-drain reset output requiring external pull-up, ±2.5% reset threshold accuracy over temperature, 1.58V threshold tolerance, 140ms guaranteed timeout, and dedicated RESET IN comparator referenced to +1.27V for secondary voltage supervision.

Technical Context

The MAX6389XS16D3+ integrates a precision bandgap reference and comparator to monitor VCC against a fixed 1.58V threshold while simultaneously comparing an external voltage at RESET IN to an internal +1.27V reference. Reset asserts if either monitored voltage falls below its respective threshold.

It features a monolithic timer that guarantees ≥140ms reset assertion after VCC or RESET IN recovers, with immunity to negative-going VCC transients up to 35µs at 100mV overdrive. The open-drain RESET output ensures compatibility with mixed-voltage I/O domains and requires no internal pull-up.

Key Specifications

Pinout & Package

MAX6389XS16D3+ is housed in a 4-pin SC70 package (package code X4-1), measuring 1.0mm × 1.0mm × 0.55mm, with wettable flank leads for automated optical inspection. Pin 1 = VCC, Pin 2 = RESET, Pin 3 = RESET IN, Pin 4 = GND.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6389XS16D3+, the µDFN variant offers superior thermal performance in constrained layouts, while the TPS3808G15DBVR trades dual-monitoring capability for higher threshold precision and push-pull simplicity-neither is pin-compatible, and both require PCB redesign.

Availability

MAX6389XS16D3+ is available at Aetrix Electronics and suitable for battery-powered portable devices, dual-voltage microcontroller systems, and low-power IoT edge nodes requiring stable component supply, long-term lifecycle support, and guaranteed lead-free compliance.

Supply support for MAX6389XS16D3+ 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 power, sensing, and interface applications, with emphasis on low-power, high-reliability solutions for industrial and automotive markets.

The MAX6381–MAX6390 family was engineered specifically for space-constrained, battery-sensitive systems needing dual-supply monitoring, ultra-low ICC, and guaranteed reset behavior across extreme temperatures.

FAQ

What is the exact reset threshold voltage of MAX6389XS16D3+ and how stable is it over temperature?

The MAX6389XS16D3+ has a factory-set reset threshold of 1.58V, specified with ±2.5% tolerance over the full operating temperature range of –40°C to +125°C. This stability is achieved through laser-trimmed bandgap reference circuitry and is documented in the Electrical Characteristics table under "VCC Reset Threshold" with tempco of 60ppm/°C. The MAX6389XS16D3+ maintains this accuracy without external calibration.

Does MAX6389XS16D3+ support monitoring a second voltage, and how is it implemented?

Yes, MAX6389XS16D3+ supports dual-voltage supervision via its dedicated RESET IN pin, which compares an external voltage to an internal +1.27V reference. To implement, connect a resistor divider between the secondary supply and GND, with the midpoint fed to RESET IN. The threshold is set by V_INTH = 1.27V × (R1/R2 + 1). The MAX6389XS16D3+ 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 on MAX6389XS16D3+, and what pull-up value is recommended?

The open-drain RESET output on MAX6389XS16D3+ actively pulls low to assert reset and floats high when deasserted, requiring an external pull-up resistor to the target logic rail (e.g., 3.3V or 1.8V). A 10kΩ–100kΩ resistor is typical; the MAX6389XS16D3+ guarantees sinking ≥80µA while maintaining VOL ≤0.3V. This architecture enables level translation and wired-OR reset bus configurations not possible with push-pull outputs.

Can MAX6389XS16D3+ operate reliably during deep brownout conditions, and down to what VCC level?

Yes, MAX6389XS16D3+ guarantees correct RESET output logic state down to VCC = 1.0V, as confirmed in the Absolute Maximum Ratings and Electrical Characteristics tables. Below 1.0V, operation is not specified. This ensures deterministic reset hold during severe brownout, preventing µP execution errors. The device draws only 3µA at 1.8V, making it ideal for battery-powered systems where VCC may sag near cutoff.

Is MAX6389XS16D3+ pin-compatible with older Maxim reset ICs like MAX809 or MAX6326?

No, MAX6389XS16D3+ is not pin-compatible with MAX809 (3-pin SOT23) or MAX6326 (3-pin SOT23), as it uses a 4-pin SC70 package with dedicated RESET IN functionality. While the datasheet notes "pin compatible with" those parts *in functional families*, the physical pinout differs: MAX6389XS16D3+ allocates Pin 3 to RESET IN, whereas MAX809 uses Pin 3 for manual reset or is unassigned. Board-level replacement requires layout revision.