Analog Devices Inc./Maxim Integrated MAX6837HXSD3

Overview

MAX6837HXSD3 from Maxim Integrated is an ultra-low-voltage microprocessor supervisory circuit with open-drain active-low reset output, factory-set 1.313V reset threshold, and 210ms reset timeout period. It monitors +1.2V to +1.8V supply rails in portable and battery-powered systems, asserting reset during brownout or power-down events while consuming only 7.5µA typical supply current. Designed for critical µP power monitoring in space-constrained applications.

For engineers reviewing the MAX6837HXSD3 datasheet, MAX6837HXSD3 pinout, MAX6837HXSD3 application, or MAX6837HXSD3 equivalent, key selection considerations include its SC70-4 open-drain RESET output requiring external pullup, debounced manual reset input (MR), ±2.5% threshold accuracy over temperature, and immunity to short VCC transients - all critical for reliable low-voltage system initialization.

Technical Context

The MAX6837HXSD3 implements a precision voltage comparator with 444mV internal reference, comparing VCC against a factory-trimmed threshold (1.313V) to trigger reset assertion when supply drops below that level. Its reset timeout is fixed at 210ms (D3 option), guaranteed valid down to VCC = 0.55V for active-low operation.

It features a debounced MR input with internal 20kΩ pullup to VCC, supporting CMOS-level or open-drain manual reset initiation without external filtering. The open-drain RESET output allows level-shifting and bidirectional reset interfacing with µPs, requiring an external pullup resistor connected to a voltage up to 6.0V.

Key Specifications

Pinout & Package

MAX6837HXSD3 is housed in a 4-pin SC70-4 package (2.0mm × 2.1mm, 0.65mm pitch), optimized for high-density PCB layouts in portable electronics.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6837VXSD3, the MAX6837HXSD3 ensures correct reset timing for 1.3V systems due to its tighter threshold match; versus MAX6316HCS29D3-T, it retains hardware-managed manual reset and open-drain flexibility at the cost of one additional pin - critical for field-serviceable medical and industrial designs.

Availability

MAX6837HXSD3 is available at Aetrix Electronics and suitable for battery-powered IoT sensor nodes, wearable health monitors, low-voltage FPGA configuration monitors, and medical point-of-care diagnostic modules requiring stable component supply across extended production lifecycles.

Supply support for MAX6837HXSD3 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 management, sensing, and interface applications in industrial, automotive, and computing markets.

The MAX6832–MAX6840 family delivers ultra-low-voltage supervisory circuits targeting portable, battery-operated, and energy-sensitive systems where supply rails fall below 1.8V and quiescent current must remain under 10µA.

FAQ

What is the exact reset threshold voltage of the MAX6837HXSD3 and how stable is it over temperature?

The MAX6837HXSD3 has a factory-set reset threshold of 1.313V with ±2.5% accuracy over the full operating temperature range of -40°C to +85°C. This specification is guaranteed by design and confirmed in the Electrical Characteristics table of the official datasheet. The threshold remains stable due to on-chip trimming and a precision 444mV bandgap reference. At +25°C, typical variation is within ±0.5%, making MAX6837HXSD3 suitable for applications demanding tight supply-margin monitoring in 1.3V systems.

Does the MAX6837HXSD3 require an external pullup resistor on its RESET pin, and what value is recommended?

Yes, the MAX6837HXSD3 features an open-drain active-low RESET output and requires an external pullup resistor. The datasheet specifies that RESET can be pulled up to any voltage between 0V and 6.0V. A typical value is 10kΩ to 100kΩ, selected based on rise time requirements and bus loading. For a 3.3V system with ≤100ns rise time, 10kΩ is appropriate; for ultra-low-power applications where RESET is only sampled infrequently, 100kΩ minimizes current draw. The MAX6837HXSD3 itself sinks up to 200µA at VCC ≥1.5V when RESET is asserted.

Can the MAX6837HXSD3 monitor a supply voltage lower than its own VCC pin voltage?

No - the MAX6837HXSD3 monitors the voltage applied to its VCC pin; it does not support independent supply monitoring like the RESET-IN variants (e.g., MAX6838/MAX6839/MAX6840). Its reset decision is based solely on the VCC rail it is powered from. To supervise a lower voltage (e.g., 0.9V), you would need a device with RESET-IN capability and an external resistive divider. The MAX6837HXSD3 is designed specifically for direct monitoring of 1.2V–1.8V supplies powering the IC itself.

What is the function of the MR pin on the MAX6837HXSD3, and does it need external components?

The MR (Manual Reset) pin on the MAX6837HXSD3 is an active-low, debounced input with an internal 20kΩ pullup resistor to VCC. Pulling MR low forces a reset regardless of VCC level, and reset remains asserted for the full 210ms timeout after MR returns high. No external components are required: a momentary switch from MR to GND suffices. In electrically noisy environments, a 0.1µF capacitor from MR to GND adds immunity. The MAX6837HXSD3's MR accepts CMOS logic levels and tolerates pulses as short as 2µs.

Is the MAX6837HXSD3 pin-compatible with older Maxim reset supervisors like the MAX809 or MAX6381 series?

No - the MAX6837HXSD3 uses a 4-pin SC70-4 package with pinout GND/RESET/MR/VCC, whereas MAX809 is a 3-pin SOT23 with GND/RESET/VCC and no MR pin, and MAX6381 series use 5-pin SOT23-5 packages. While functional equivalents exist, physical replacement requires PCB redesign. However, the MAX6837HXSD3 is explicitly pin-compatible within its own family (e.g., MAX6835/MAX6836) and shares functional compatibility with MAX6834/MAX6840 in open-drain configurations - differing only in threshold and timeout suffixes.