Analog Devices Inc./Maxim Integrated MAX6727KASDD3+T

Overview

MAX6727KASDD3+T from Maxim Integrated is a triple-voltage microprocessor supervisory circuit in an 8-pin SOT23 package, monitoring VCC1 (4.625V threshold), VCC2 (3.075V threshold), and an externally adjustable RSTIN input (626.5mV reference). It provides two open-drain active-low reset outputs (RST and RST2), manual reset input, watchdog timer with 35s startup/1.12s normal timeout, and operates from -40°C to +85°C. It ensures reliable system boot and brownout recovery in multivoltage embedded power rails.

For engineers reviewing the MAX6727KASDD3+T datasheet, MAX6727KASDD3+T pinout, MAX6727KASDD3+T application, or MAX6727KASDD3+T equivalent, key selection criteria include dual independent reset outputs, factory-trimmed dual-supply thresholds with third-voltage adjustability, guaranteed reset validity down to VCC = 0.8V, and integrated watchdog with long-startup mode for complex firmware initialization.

Technical Context

The MAX6727KASDD3+T implements dual independent voltage comparators for VCC1 and VCC2, plus a high-impedance RSTIN comparator referenced to a 626.5mV internal bandgap. Its reset logic asserts both RST and RST2 simultaneously upon any monitored supply drop below threshold, MR low pulse, or watchdog timeout - and holds reset for a fixed 210ms minimum timeout period after recovery.

It features separate push-pull or open-drain output drivers: RST is referenced to VCC1, RST2 to VCC2; both are open-drain in this variant. The watchdog uses dual-mode timing - 35s min after reset assertion, then switches to 1.12s min after first WDI edge - enabling robust boot supervision without false triggers during initialization.

Key Specifications

Pinout & Package

MAX6727KASDD3+T is housed in an 8-pin SOT23-8 package (2.0mm × 2.1mm × 0.95mm), optimized for space-constrained PCB layouts in portable and industrial equipment.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar triple-voltage supervisory applications.

Compared with MAX6725KAHDD3+T and TPS3808G33DBVR, the MAX6727KASDD3+T uniquely delivers dual open-drain reset outputs with independent VCC referencing, full RSTIN adjustability, and dual-mode watchdog - making it optimal for complex multivoltage systems requiring synchronized yet electrically isolated reset control and runtime fault detection.

Availability

MAX6727KASDD3+T is available at Aetrix Electronics and suitable for industrial PLCs, network infrastructure equipment, medical diagnostics devices, and automotive infotainment systems requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for MAX6727KASDD3+T 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 demanding industrial, communications, and computing applications.

The MAX6715–MAX6729 family delivers ultra-low-voltage, multirail supervisory circuits targeting space-constrained, battery-sensitive, and high-reliability embedded systems where deterministic reset behavior and brownout immunity are critical.

FAQ

What is the function of the RSTIN pin on the MAX6727KASDD3+T?

The RSTIN pin on the MAX6727KASDD3+T is a high-impedance input that connects to an internal 626.5mV precision reference comparator. When the voltage at RSTIN falls below this threshold - typically set using an external resistor divider - the device asserts both RST and RST2 outputs. This enables monitoring of a third supply voltage (e.g., 1.2V, 1.8V) without requiring additional supervisory ICs. The MAX6727KASDD3+T guarantees accurate trip points across temperature and supply variations.

Does the MAX6727KASDD3+T support both push-pull and open-drain reset outputs?

No - the MAX6727KASDD3+T provides two open-drain active-low reset outputs: RST (referenced to VCC1) and RST2 (referenced to VCC2). Both require external pull-up resistors to their respective supply rails. Unlike variants such as MAX6726, this part does not include push-pull outputs. The open-drain configuration allows flexible voltage-level translation and wired-OR reset bus implementation, which is essential in multivoltage systems where reset signals must be shared across domains.

How does the watchdog timer in the MAX6727KASDD3+T operate during system startup?

The MAX6727KASDD3+T watchdog timer operates in dual-mode: after any reset event (power-up, brownout, MR, or prior watchdog timeout), it enters a 35s minimum startup period. During this time, the µP can complete bootloader execution and OS initialization without needing to toggle WDI. Once the first valid WDI edge occurs, the timer switches to its normal 1.12s minimum timeout mode. This architecture prevents premature resets during boot while maintaining strict runtime supervision - a key feature of the MAX6727KASDD3+T design.

What are the exact reset threshold voltages programmed into the MAX6727KASDD3+T?

The MAX6727KASDD3+T has factory-trimmed reset thresholds of 4.625V for VCC1 and 3.075V for VCC2, as indicated by the "AS" suffix per Maxim's Reset Voltage Threshold Suffix Guide. These values are guaranteed over temperature (-40°C to +85°C) with ±1.5% tolerance. The RSTIN input uses a fixed 626.5mV internal reference, enabling precise third-voltage monitoring via external resistor dividers. All thresholds are production-tested and documented in the MAX6727KASDD3+T electrical characteristics table.

Can the MAX6727KASDD3+T operate reliably when VCC1 drops below 1.0V?

Yes - the MAX6727KASDD3+T is guaranteed to maintain valid reset output logic states as long as either VCC1 or VCC2 remains above 0.8V. This specification ensures deterministic behavior during deep brownout conditions where VCC1 may sag to near-zero while VCC2 remains marginally active. The device continues asserting reset until both supplies recover above their respective thresholds and the 210ms timeout expires. This capability is explicitly validated in the MAX6727KASDD3+T absolute maximum ratings and functional description.