Analog Devices Inc./Maxim Integrated MAX6725KAWGD3+T

Overview

MAX6725KAWGD3+T from Maxim Integrated is a triple-voltage microprocessor supervisory circuit in an 8-pin SOT23 package, monitoring VCC1 (primary), VCC2 (secondary), and RSTIN (auxiliary) supply rails with factory-trimmed thresholds of 2.925V (VTH1), 2.188V (VTH2), and 626.5mV reference for RSTIN. It provides active-low open-drain RST and RST2 outputs, manual reset input (MR), watchdog timer (35s startup / 1.12s normal timeout), and operates from -40°C to +85°C. Used in multivoltage telecom and industrial systems requiring reliable power-up sequencing and brownout detection.

For engineers reviewing the MAX6725KAWGD3+T datasheet, MAX6725KAWGD3+T pinout, MAX6725KAWGD3+T application, or MAX6725KAWGD3+T equivalent, key selection criteria include dual independent reset outputs, guaranteed reset validity down to VCC1/VCC2 = 0.8V, adjustable third-voltage monitoring via RSTIN, watchdog startup timing behavior, and SOT23-8 footprint compatibility with space-constrained embedded designs.

Technical Context

The MAX6725KAWGD3+T integrates three independent voltage comparators - one for VCC1 (2.925V threshold), one for VCC2 (2.188V threshold), and one for RSTIN referenced to a 626.5mV internal bandgap - each feeding a shared reset timeout timer (210ms min). Its dual open-drain reset outputs (RST and RST2) are independently driven but share assertion logic, with RST referenced to VCC1 and RST2 to VCC2.

This device implements a dual-mode watchdog: a 35s minimum initial timeout after any reset event (power-up, MR, or watchdog timeout), followed by a 1.12s minimum normal-mode timeout triggered by the first WDI edge. MR features a 50kΩ internal pullup to VCC1 and 200ns propagation delay to reset assertion.

Key Specifications

Pinout & Package

MAX6725KAWGD3+T is housed in an 8-pin SOT23-8 package (2.0mm × 2.1mm × 1.1mm height), compatible with standard reflow profiles and high-density PCB layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6725KAWGD3+T, MAX6726KAUD3+T offers push-pull drive for reduced BOM count, while TPS3808G33DBVR reduces functionality and package size for less complex power-monitoring needs - neither is pin-compatible, but both serve overlapping supervisory roles in different system complexity tiers.

Availability

MAX6725KAWGD3+T is available at Aetrix Electronics and suitable for telecom infrastructure, industrial PLCs, battery-powered medical devices, and consumer set-top boxes requiring stable component supply, long-term lifecycle support, and guaranteed performance across extended temperature ranges.

Supply support for MAX6725KAWGD3+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) is a semiconductor company specializing in precision analog, mixed-signal, and power management ICs for industrial, communications, and computing markets.

The MAX6715–MAX6729 family was designed to replace discrete reset circuits in multivoltage embedded systems, delivering compact, factory-trimmed supervision with configurable timing and triple-rail monitoring capability.

FAQ

What is the function of the RSTIN pin on the MAX6725KAWGD3+T?

The RSTIN pin on the MAX6725KAWGD3+T serves as a high-impedance auxiliary voltage monitor input with a 626.5mV internal reference. When used with an external resistor divider, it enables supervision of a third supply rail down to 0.62V. The MAX6725KAWGD3+T asserts reset if RSTIN falls below this threshold, and its 3mV hysteresis improves noise immunity. RSTIN must be tied to VCC1 or VCC2 if unused.

Does the MAX6725KAWGD3+T provide both active-high and active-low reset outputs?

No, the MAX6725KAWGD3+T provides two active-low open-drain reset outputs: RST (referenced to VCC1) and RST2 (referenced to VCC2). It does not include an active-high reset output. Both outputs assert low simultaneously when any monitored supply (VCC1, VCC2, or RSTIN) falls below its threshold, MR is pulled low, or the watchdog times out. External pullup resistors are required for proper logic-level translation.

How does the watchdog timer operate in the MAX6725KAWGD3+T?

The MAX6725KAWGD3+T implements a dual-mode watchdog: after any reset event (power-up, MR, or prior watchdog timeout), it enters a 35s minimum startup mode to accommodate firmware boot. Once the first valid WDI edge occurs, it switches to a 1.12s minimum normal timeout mode. The MAX6725KAWGD3+T resets if WDI remains static beyond the active timeout period, ensuring robust software execution monitoring.

What is the guaranteed operating voltage range for valid reset assertion on the MAX6725KAWGD3+T?

The MAX6725KAWGD3+T guarantees correct reset output logic state as long as either VCC1 or VCC2 remains above 0.8V. Below this level, reset behavior is not specified. This feature ensures reliable operation during deep brownout conditions common in battery-powered or unregulated supply environments, distinguishing it from supervisors requiring higher minimum supply voltages for reset integrity.

Can the MAX6725KAWGD3+T monitor negative supply voltages?

Yes, the MAX6725KAWGD3+T can monitor negative supplies using the RSTIN or PFI pins with appropriate external resistor networks. For example, connecting a negative rail through a voltage divider to RSTIN allows detection when the divided voltage crosses the 626.5mV internal reference. The MAX6725KAWGD3+T's input structure supports such configurations, though accuracy depends on resistor tolerance and temperature drift of the external network.