Analog Devices Inc./Maxim Integrated MAX6844UKD2

Overview

The MAX6844UKD2 from Maxim Integrated is an ultra-low-voltage microprocessor supervisory circuit with adjustable reset threshold, active-high push-pull reset output, 30ms reset timeout, and operation down to VCC = 0.75V. It monitors power supplies in portable and battery-powered systems, provides manual reset input with internal 20kΩ pullup, and guarantees valid reset assertion down to VCC = 0.55V.

For engineers reviewing the MAX6844UKD2 datasheet, MAX6844UKD2 pinout, MAX6844UKD2 application, or MAX6844UKD2 equivalent, this page delivers verified specifications, SOT23-5 package mapping, reset timing behavior, RESET IN threshold calibration, and real-world selection guidance for low-voltage µP monitoring in space-constrained designs.

Technical Context

The MAX6844UKD2 uses a precision bandgap-referenced comparator to monitor the voltage differential between VCC and the RESET IN pin, with a fixed internal reference of 187.4mV (±3.2mV) referenced to VCC. Its reset assertion is triggered when RESET IN falls below this threshold, and reset remains asserted for a factory-set 30ms timeout after RESET IN rises above threshold and MR is released.

It features a debounced manual reset input (MR) with 150ns glitch rejection and 1µs minimum pulse width, and its active-high push-pull RESET output drives high with VOH ≥ 0.8×VCC (ISOURCE = 40µA) and low with VOL ≤ 0.2×VCC (ISINK = 80µA), ensuring reliable interface with CMOS logic across its operating range.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, surface-mount, lead-free compatible (replaces -T with +T), footprint per JEDEC MO-178AB.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6843UKD2, the MAX6844UKD2 eliminates level-shifting needs for active-high interfaces; compared with TPS3808G30DBVR, it enables precise low-voltage trip points and reduces power by 40% in 1.5V systems.

Availability

MAX6844UKD2 is available at Aetrix Electronics and suitable for portable medical sensors, battery-powered IoT nodes, and industrial edge controllers requiring stable component supply with guaranteed long-term sourcing.

Supply support for MAX6844UKD2 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 high reliability and low power.

The MAX6841–MAX6845 family was developed specifically for ultra-low-voltage microprocessor supervision in portable and energy-constrained systems, addressing the need for sub-1V reset accuracy and minimal quiescent current.

FAQ

What is the exact reset timeout period of the MAX6844UKD2?

The MAX6844UKD2 has a factory-set reset active timeout period of 30ms (typical), with min/max values of 20ms and 40ms respectively. This fixed delay begins after VCC or RESET IN rises above the threshold and MR is deasserted, ensuring sufficient hold time for microprocessor initialization before release. The D2 suffix in MAX6844UKD2 explicitly denotes this 30ms option per Table 2 of the datasheet.

How do I configure the reset threshold for MAX6844UKD2?

The MAX6844UKD2 uses the RESET IN pin with an internal 187.4mV reference (vs. VCC) to enable adjustable threshold configuration. Connect an external resistor divider from VCC to GND, tapping the junction to RESET IN. For example, to set a 1.0V trip point, use R1 = 422kΩ and R2 = 100kΩ (R2 to GND). The MAX6844UKD2 asserts reset when the voltage at RESET IN falls below 187.4mV, corresponding to VCC dropping below the desired threshold.

Does MAX6844UKD2 support operation below 1.0V?

Yes, the MAX6844UKD2 operates with VCC as low as 0.75V and guarantees valid reset assertion down to VCC = 0.55V. Its internal circuitry remains functional across this range, and the active-high push-pull RESET output maintains VOH ≥ 0.8×VCC and VOL ≤ 0.2×VCC even at 0.75V, enabling direct interface with low-voltage logic families used in modern SoCs and MCUs.

What is the function of the MR pin on MAX6844UKD2?

The MR (Manual Reset) pin on MAX6844UKD2 is an active-low input with an internal 20kΩ pullup to VCC. Pulling MR to GND forces an immediate reset regardless of VCC or RESET IN status. Reset remains asserted for the full 30ms timeout after MR is released. The pin rejects glitches as short as 150ns and accepts pulses as brief as 1µs, making it suitable for pushbutton or logic-driven reset initiation without external debounce components.

Can MAX6844UKD2 replace MAX6841 or MAX6842 in existing designs?

No, MAX6844UKD2 is not a drop-in replacement for MAX6841 or MAX6842 due to fundamental differences: MAX6844UKD2 requires an external resistor divider on RESET IN for threshold setting, while MAX6841/MAX6842 use factory-trimmed thresholds; additionally, MAX6844UKD2 has only one active-high push-pull RESET output, whereas MAX6841 offers dual outputs and MAX6842 includes open-drain capability. Board-level changes are required for substitution.