Analog Devices Inc./Maxim Integrated MAX6726KASDD3+

Overview

MAX6726KASDD3+ 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 (MR), watchdog timer (1.12s normal / 35s startup timeout), and operates from -40°C to +85°C. It ensures reliable system reset in multivoltage embedded power rails for telecom and industrial controllers.

For engineers reviewing the MAX6726KASDD3+ datasheet, MAX6726KASDD3+ pinout, MAX6726KASDD3+ application, or MAX6726KASDD3+ equivalent, this page delivers verified electrical specs, dual reset output logic behavior, RSTIN threshold calibration guidance, MR timing constraints, and real-world substitution options - all confirmed against Maxim's official MAX6715–MAX6729 family documentation.

Technical Context

The MAX6726KASDD3+ implements a dual-mode watchdog timer with a guaranteed 35s minimum startup period after any reset event and a 1.12s minimum normal timeout, triggered by WDI edge transitions. Its internal comparators monitor three independent supply rails: VCC1 (primary, factory-trimmed 4.625V threshold), VCC2 (secondary, 3.075V), and RSTIN (adjustable via resistor divider referenced to 626.5mV).

It guarantees valid reset assertion down to VCC1 or VCC2 = 0.8V and supports both push-pull RST (referenced to VCC1) and push-pull RST2 (referenced to VCC2), with MR featuring a 50kΩ internal pullup and 1µs minimum pulse width requirement. Reset timeout is fixed at 210ms (typical) per the "D3" suffix.

Key Specifications

Pinout & Package

MAX6726KASDD3+ uses an 8-pin SOT23-8 package (3.0mm × 1.6mm × 1.1mm height), optimized for high-density PCB layouts in space-constrained applications such as portable equipment and modular telecom modules.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6726KASDD3+, MAX6725KAUDD3+ offers identical supervision logic but open-drain outputs for bus-sharing, while TPS3808G33DBVR reduces cost and size at the expense of triple-rail capability and dual-output flexibility - making MAX6726KASDD3+ optimal for complex multivoltage systems requiring deterministic, independent reset signaling.

Availability

MAX6726KASDD3+ is available at Aetrix Electronics and suitable for telecom infrastructure, industrial PLCs, and server management controllers requiring stable component supply, long-term lifecycle assurance, and guaranteed lead-free compliance.

Supply support for MAX6726KASDD3+ 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 demanding industrial, automotive, and communications applications, with emphasis on reliability, low power, and high integration.

The MAX6715–MAX6729 family was engineered specifically for multivoltage microprocessor systems requiring simultaneous monitoring of primary, secondary, and auxiliary rails - delivering compact, single-chip supervision with configurable reset logic and watchdog intelligence.

FAQ

What is the exact reset threshold voltage for VCC1 on the MAX6726KASDD3+?

The MAX6726KASDD3+ has a factory-trimmed VCC1 reset threshold of 4.625V (minimum 4.500V, maximum 4.750V) with ±0.5% hysteresis. This value is encoded in the "AS" suffix per Maxim's Reset Voltage Threshold Suffix Guide and is guaranteed over -40°C to +85°C. The threshold is referenced to the VCC1 supply itself and remains stable due to internal bandgap regulation.

Does the MAX6726KASDD3+ support both active-high and active-low reset outputs?

Yes, the MAX6726KASDD3+ provides two independent reset outputs: Pin 1 (RST) is an active-high push-pull output referenced to VCC1, and Pin 8 (RST2) is an active-low push-pull output referenced to VCC2. Both are driven internally - no external pull resistors are needed - and assert synchronously when any monitored supply falls below its threshold.

How is the third supply voltage monitored using RSTIN on the MAX6726KASDD3+?

The MAX6726KASDD3+ uses its RSTIN pin (Pin 7) with an internal 626.5mV precision reference to monitor a third supply. A resistor divider (R1/R2) scales the target supply voltage so that when it drops to the desired trip point, the voltage at RSTIN equals 626.5mV. For example, to monitor a 1.8V rail at 1.62V, use R1 = 180kΩ and R2 = 100kΩ per the formula V_{EXT_TH} = 626.5mV × (R1 + R2)/R2.

What is the function of the "D3" suffix in MAX6726KASDD3+?

"D3" denotes the reset timeout period: 210ms typical (140ms minimum, 280ms maximum). This timeout defines the minimum duration RST and RST2 remain asserted after all monitored supplies rise above their thresholds. It is factory-programmed and non-adjustable; other options include D1 (1.65ms), D2 (13.2ms), D5 (420ms), and D6 (840ms).

Can the MAX6726KASDD3+ operate reliably during deep supply brownouts?

Yes - the MAX6726KASDD3+ guarantees valid reset output logic states down to VCC1 or VCC2 = 0.8V. Its internal biasing and comparator design maintain correct reset assertion/deassertion even as supplies sag below 1.0V, ensuring deterministic behavior during severe brownout events where many supervisors fail silently or oscillate.