Analog Devices Inc./Maxim Integrated MAX6839XSD3

Overview

MAX6839XSD3 from Maxim Integrated is a push-pull active-high microprocessor supervisory circuit in 4-pin SC70 package, designed to monitor supply voltage via external resistive divider at RESET-IN pin with 444mV internal reference, assert reset for 210ms after threshold breach, and operate down to VCC = 0.75V with 7.5µA typical supply current - used in low-voltage portable systems requiring precise brownout protection.

For engineers reviewing the MAX6839XSD3 datasheet, MAX6839XSD3 pinout, MAX6839XSD3 application, or MAX6839XSD3 equivalent, key selection criteria include its adjustable threshold architecture (RESET-IN), 210ms timeout period (D3 suffix), active-high push-pull output, ±3.0% VRSTIN accuracy over -40°C to +85°C, and compatibility with 1.1V–3.3V monitored supplies.

Technical Context

The MAX6839XSD3 uses an internal 444mV precision reference to compare externally divided supply voltage at RESET-IN; reset assertion occurs when RESET-IN falls below this threshold, independent of VCC monitoring. Its push-pull active-high RESET output drives high during fault conditions and remains asserted for exactly 210ms after RESET-IN recovers.

This variant belongs to the MAX6838–MAX6840 subgroup featuring RESET-IN input instead of direct VCC monitoring, enabling flexible low-voltage trip points (e.g., 0.44V–3.3V) using high-impedance resistor networks. It excludes manual reset (MR) and debounced inputs, distinguishing it from MAX6835/MAX6836/MAX6837 variants.

Key Specifications

Pinout & Package

MAX6839XSD3 is housed in a 4-pin SC70 package (3.0mm × 1.7mm × 0.9mm), surface-mount, lead-free compatible, with thermal pad not electrically connected.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6839XSD3, MAX6836XSD3 lacks adjustable threshold capability but simplifies design when VCC is the sole monitored rail, while MAX6840XSD3 trades push-pull convenience for open-drain flexibility - neither is pin-compatible, and all three require distinct PCB layouts due to differing pin functions (RESET-IN vs. MR vs. GND placement).

Availability

MAX6839XSD3 is available at Aetrix Electronics and suitable for battery-powered IoT nodes, low-voltage FPGA configuration monitors, and wearable health monitors requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for MAX6839XSD3 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, medical, communications, and consumer applications.

The MAX6832–MAX6840 family delivers ultra-low-voltage supervision for portable and energy-constrained systems, emphasizing minimal quiescent current, small SC70 packaging, and flexible reset architectures including RESET-IN and multiple timeout options.

FAQ

What is the exact reset timeout period for MAX6839XSD3?

The MAX6839XSD3 has a fixed reset active timeout period of 210ms, corresponding to the D3 suffix in its ordering code. This duration is guaranteed over the full -40°C to +85°C operating temperature range and begins when RESET-IN rises above the 444mV threshold after a fault condition. The 210ms value ensures compatibility with most microprocessors' minimum reset hold time requirements without external timing components.

Does MAX6839XSD3 monitor VCC directly or use an external reference?

MAX6839XSD3 does not monitor VCC directly. Instead, it uses the RESET-IN pin to monitor an externally divided voltage - the internal 444mV reference is compared against the voltage applied to RESET-IN. VCC (1.1V–3.3V) only powers the IC; accuracy of the 444mV reference is guaranteed only when VCC ≥ 1.1V per the datasheet Electrical Characteristics table.

What is the minimum VCC required for MAX6839XSD3 to guarantee RESET output validity?

MAX6839XSD3 guarantees valid RESET output operation down to VCC = 0.75V for active-high push-pull functionality. Below this voltage, the output may not drive reliably high during reset assertion. This specification ensures robust reset behavior across the full usable range of low-voltage battery discharge curves, especially critical in coin-cell and energy-harvesting applications.

Can MAX6839XSD3 replace a MAX809 or MAX6712 in an existing design?

No, MAX6839XSD3 cannot directly replace MAX809 or MAX6712 because it uses RESET-IN instead of VCC monitoring and has different pinout (RESET-IN/VCC/GND/RESET vs. VCC/GND/RESET). While functionally similar as supervisors, the MAX6839XSD3 requires redesign of the voltage divider network and PCB layout. Pin-compatible alternatives would be MAX6836XSD3 (for VCC-monitoring) or MAX6833XRD3 (SC70-3, VCC-monitoring, active-high).

What is the RESET-IN input leakage current specification for MAX6839XSD3?

The RESET-IN input leakage current for MAX6839XSD3 is ±25nA over the full -40°C to +85°C temperature range. This ultra-low leakage enables use of high-value resistors (e.g., 100kΩ–1MΩ) in the external divider network without introducing significant trip-point error, thereby minimizing power consumption in always-on monitoring circuits.