Analog Devices Inc./Maxim Integrated MAX6726KAYHD3+

Overview

MAX6726KAYHD3+ 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 push-pull active-high RST and active-low RST outputs, manual reset input, watchdog timer with 35s startup/1.12s normal timeout, and operates from -40°C to +85°C. Used in multivoltage embedded systems requiring reliable power sequencing and fault detection.

For engineers reviewing the MAX6726KAYHD3+ datasheet, MAX6726KAYHD3+ pinout, MAX6726KAYHD3+ application, or MAX6726KAYHD3+ equivalent, key selection criteria include its dual reset output polarity, factory-trimmed dual-threshold supervision, 210ms min reset timeout, 14µA typical supply current at 3.6V, and guaranteed reset validity down to VCC1 or VCC2 = 0.8V.

Technical Context

The MAX6726KAYHD3+ integrates three independent voltage monitors: primary (VCC1), secondary (VCC2), and auxiliary (RSTIN) with a precision 626.5mV internal reference. Its dual reset outputs-active-high RST and active-low RST-are push-pull, referenced respectively to VCC1 and VCC1, enabling direct interface with bidirectional µP reset pins without contention when used with a 4.7kΩ series resistor.

It implements a dual-mode watchdog timer: 35s minimum initial timeout after any reset event (power-up, MR, or watchdog), followed by 1.12s minimum normal timeout triggered by WDI edge transitions. The manual reset input (MR) features a 50kΩ internal pullup to VCC1 and 200ns MR-to-reset delay, supporting TTL/CMOS logic or momentary switch interfaces without external debounce.

Key Specifications

Pinout & Package

MAX6726KAYHD3+ uses an 8-pin SOT23-8 package (2.0mm × 2.1mm × 1.25mm), surface-mount, RoHS-compliant, lead-free (+ suffix).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6726KAYHD3+, MAX6725KAHGD3+ offers identical threshold accuracy and timeout but requires external pullups due to open-drain outputs, while TPS3808G33DBVR reduces functionality to single-rail monitoring with no watchdog or auxiliary input-making MAX6726KAYHD3+ the only option supporting full triple-voltage, dual-polarity, and watchdog-enabled supervision in one 8-pin SOT23.

Availability

MAX6726KAYHD3+ is available at Aetrix Electronics and suitable for industrial PLC controllers, telecom line cards, medical imaging subsystems, and network attached storage (NAS) requiring stable component supply, long-term lifecycle support, and guaranteed RoHS-compliant sourcing.

Supply support for MAX6726KAYHD3+ 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, automotive, communications, and computing markets.

The MAX6715–MAX6729 family delivers ultra-low-voltage, multi-rail µP supervision with integrated watchdog, manual reset, and power-fail monitoring-targeting space-constrained, reliability-critical embedded systems.

FAQ

What is the reset timeout period for MAX6726KAYHD3+?

The MAX6726KAYHD3+ has a minimum reset timeout period of 210ms, as indicated by the "D3" suffix in its part number. This timeout is guaranteed across the full operating temperature range (-40°C to +85°C) and ensures the reset signal remains asserted long enough for microprocessors and associated logic to complete full initialization after power-up or fault recovery. The timeout begins when all monitored supplies rise above their respective thresholds and ends 210ms later.

Does MAX6726KAYHD3+ support monitoring a third voltage rail?

Yes, MAX6726KAYHD3+ supports third-rail monitoring via its RSTIN pin, which connects to an internal 626.5mV precision reference. By using an external resistor divider between the target rail and ground, designers can set a custom reset threshold-for example, monitoring a 1.2V core supply with a 1.14V trip point. The RSTIN input draws only ±25nA, enabling high-impedance, low-power sensing without loading the monitored rail.

What are the logic polarities of the reset outputs on MAX6726KAYHD3+?

MAX6726KAYHD3+ provides two independent reset outputs: Pin 1 is an active-high push-pull RST output referenced to VCC1, and Pin 8 is an active-low push-pull RST output also referenced to VCC1. Both outputs assert simultaneously during fault conditions and maintain their respective states for the full 210ms timeout period after recovery. This dual-polarity capability eliminates the need for external inverters when interfacing with mixed-logic peripherals.

Is MAX6726KAYHD3+ compatible with manual reset switches?

Yes, MAX6726KAYHD3+ includes a dedicated MR (manual reset) input on Pin 3 with an internal 50kΩ pullup resistor to VCC1. A normally open momentary switch connected between MR and GND provides full manual reset functionality without external components. The device responds to MR pulses as short as 1µs, and reset remains active for the full 210ms timeout after the switch is released-ensuring robust, bounce-free reset initiation.

What is the supply current consumption of MAX6726KAYHD3+ at 3.6V?

The MAX6726KAYHD3+ consumes 14µA typical supply current at 3.6V, as specified in the Electrical Characteristics table. This ultra-low quiescent current is maintained across the full -40°C to +85°C temperature range and enables use in battery-backed systems such as portable medical devices and remote telemetry units where standby power budget is critical. Total current scales predictably with VCC1 and VCC2 levels, as shown in the Typical Operating Characteristics plots.