Analog Devices Inc./Maxim Integrated MAX6838XSD3

Overview

The MAX6838XSD3 from Maxim Integrated is a precision ultra-low-voltage microprocessor supervisory circuit with adjustable reset threshold, push-pull active-high RESET output, and 210ms timeout period. It monitors supply voltages via external resistive divider on RESET-IN (typical threshold 444mV), operates from VCC = 1.1V to 3.3V, draws only 7.5µA typical supply current, and guarantees valid reset assertion down to VCC = 0.75V. It is used in battery-powered embedded controllers requiring reliable brownout detection.

For engineers reviewing the MAX6838XSD3 datasheet, MAX6838XSD3 pinout, MAX6838XSD3 application, or MAX6838XSD3 equivalent, this device serves as a low-power, adjustable-threshold reset supervisor for sub-1.2V core supplies - especially where manual reset is unnecessary but precise voltage monitoring of auxiliary rails (e.g., DC/DC converter feedback nodes) is required.

Technical Context

The MAX6838XSD3 implements a high-impedance comparator that references an internal 444mV bandgap voltage at the RESET-IN pin; reset asserts when RESET-IN falls below this threshold. Its push-pull active-high RESET output drives directly into CMOS inputs without external pullup, eliminating level-shifting complexity.

VCC powers the internal circuitry but is not monitored; only RESET-IN determines reset assertion. The 210ms timeout (D3 suffix) is fixed and temperature-stable (±2.5% threshold accuracy over −40°C to +85°C), and the device rejects fast transients via built-in hysteresis and glitch immunity.

Key Specifications

Pinout & Package

MAX6838XSD3 is housed in a 4-pin SC70-4 package (2.0mm × 2.1mm, 0.5mm pitch), optimized for space-constrained portable designs.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar voltage supervisor applications.

Compared with MAX6839XSD3, the MAX6838XSD3 offers design flexibility through adjustable thresholding at the cost of one extra resistor; compared with TLV809E21DBZR, it enables sub-1V monitoring and eliminates pullup dependency, albeit with higher quiescent current and larger package.

Availability

MAX6838XSD3 is available at Aetrix Electronics and suitable for portable equipment, industrial controllers, and battery-powered IoT devices requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MAX6838XSD3 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 in industrial, computing, and communications systems.

The MAX6832–MAX6840 family delivers ultra-low-voltage supervision for next-generation energy-efficient processors and battery-operated devices, emphasizing minimal current draw and flexible threshold configuration.

FAQ

What is the function of the RESET-IN pin on the MAX6838XSD3?

The RESET-IN pin on the MAX6838XSD3 is a high-impedance input that connects to an external resistive divider to set the reset trip voltage. The internal comparator references a precise 444mV threshold; reset asserts when the voltage at RESET-IN falls below this value. This allows the MAX6838XSD3 to supervise supply rails as low as 0.44V without modifying the IC itself - a key capability distinguishing it from fixed-threshold supervisors like the MAX6839XSD3.

Does the MAX6838XSD3 monitor its own VCC supply?

No, the MAX6838XSD3 does not monitor VCC. VCC (pin 2) solely powers the internal circuitry and must be maintained between 1.1V and 3.3V for guaranteed operation. Only the voltage applied to the RESET-IN pin (pin 1) determines reset assertion. This decoupling allows the MAX6838XSD3 to supervise a different rail - for example, using a 1.2V VCC to monitor a 0.6V core supply via RESET-IN - which is explicitly supported in the datasheet's Figure 1 and Applications Information section.

What is the significance of the 'D3' suffix in MAX6838XSD3?

Within the MAX6832–MAX6840 family, the 'D3' suffix denotes a fixed reset timeout period of 210ms. This value is factory-trimmed and guaranteed over temperature (−40°C to +85°C). The timeout begins when RESET-IN rises above the 444mV threshold and ends when the RESET output deasserts. Unlike programmable supervisors, the MAX6838XSD3 offers no user-adjustable delay - the D3 option provides a robust, predictable hold time ideal for systems requiring consistent post-brownout recovery sequencing.

Can the MAX6838XSD3 drive a microcontroller reset pin directly?

Yes, the MAX6838XSD3 can drive a microcontroller reset pin directly because its RESET output (pin 4) is push-pull active-high and fully specified down to VCC = 0.75V. It sources up to 50µA at VOH ≥ 0.8×VCC and sinks up to 150µA at VOL ≤ 0.2×VCC, meeting standard CMOS input requirements. No external pullup resistor is needed - unlike open-drain alternatives such as the MAX6840XSD3 - reducing component count and improving noise margin in compact layouts.

What is the minimum VCC required for guaranteed RESET-IN threshold accuracy in the MAX6838XSD3?

The MAX6838XSD3 requires VCC ≥ 1.1V to guarantee RESET-IN threshold accuracy of ±3.0% over temperature (−40°C to +85°C), as stated in the Electrical Characteristics table. Below 1.1V, the internal reference may deviate beyond spec, though the device remains functional. This requirement ensures the 444mV bandgap reference remains stable - critical when using high-value resistors in the external divider to minimize current draw in battery-critical applications.