Analog Devices Inc./Maxim Integrated MAX6728AKATGD3+T

Overview

MAX6728AKATGD3+T from Maxim Integrated is a dual-supply ultra-low-voltage microprocessor supervisory circuit in 8-pin SOT23 package, monitoring VCC1 (4.625V factory-trimmed threshold) and VCC2 (0.788V typical threshold), with power-fail input (PFI), power-fail output (PFO), manual-reset (MR), and 140ms minimum reset timeout. It ensures reliable system reset in telecom power supplies and industrial controllers during brownout conditions.

For engineers reviewing the MAX6728AKATGD3+T datasheet, MAX6728AKATGD3+T pinout, MAX6728AKATGD3+T application, or MAX6728AKATGD3+T equivalent, key selection criteria include its dual-voltage monitoring capability down to 0.8V supply validity, PFI/PFO support for early power-fail warning, and guaranteed 140ms reset assertion after supply recovery - critical for safe firmware initialization in battery-backed systems.

Technical Context

The MAX6728AKATGD3+T implements independent voltage comparators for VCC1 and VCC2, each with 0.5% hysteresis and 20ppm/°C tempco, ensuring stable reset thresholds across -40°C to +125°C. Its internal reset timer guarantees ≥140ms assertion after all monitored supplies exceed thresholds.

It integrates a dedicated power-fail comparator (PFI → PFO) with 2µs propagation delay and 3mV hysteresis, plus MR input with 50kΩ internal pullup and 1µs minimum pulse width support - enabling robust manual reset without external components.

Key Specifications

Pinout & Package

MAX6728AKATGD3+T is housed in an 8-pin SOT23 package (package code K8SN+1, outline 21-0078), with 0.65mm pitch, 2.9mm × 1.6mm footprint, and thermal resistance θJA = 180°C/W on multilayer board.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual-supply supervisory applications.

Compared with MAX6728AKATGD3+T, MAX6729AKATGD3+T offers push-pull drive for simplified interfacing but sacrifices wired-OR capability, while TPS3808G33DBVR reduces cost and current draw at the expense of dual-supply supervision and power-fail functionality - making MAX6728AKATGD3+T optimal for safety-critical multirail systems requiring independent fault signaling.

Availability

MAX6728AKATGD3+T is available at Aetrix Electronics and suitable for telecom infrastructure, industrial automation, and automotive ADAS applications requiring stable component supply, long-term lifecycle support, and AEC-Q100-aligned reliability.

Supply support for MAX6728AKATGD3+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 and mixed-signal ICs for demanding industrial, automotive, and communications applications.

The MAX6715A–MAX6729A family delivers ultra-low-voltage supervisory circuits optimized for multirail systems where simultaneous monitoring of primary and secondary supplies is essential for fail-safe operation.

FAQ

What is the exact reset threshold voltage for VCC1 on MAX6728AKATGD3+T?

The MAX6728AKATGD3+T has a factory-trimmed VCC1 reset threshold of 4.625V (typical), with guaranteed range 4.500V to 4.750V at 25°C. This value is fixed by the 'K' suffix in the part number per Maxim's Reset Voltage Threshold Suffix Guide and applies across the full -40°C to +125°C operating range with ±20ppm/°C tempco.

Does MAX6728AKATGD3+T support monitoring a third voltage rail?

No, MAX6728AKATGD3+T does not use the RSTIN pin for third-rail monitoring. Per the Pin Description table, RSTIN is unused in the MAX6728A/MAX6729A variants and must be tied to VCC1 or GND. For triple-voltage supervision, select MAX6723A–MAX6727A variants which implement the adjustable RSTIN input with 626.5mV internal reference.

What is the function of the PFI and PFO pins on MAX6728AKATGD3+T?

On MAX6728AKATGD3+T, PFI is a high-impedance input (±100nA) that monitors an external voltage via resistor divider against a 626.5mV internal reference; PFO is an active-low open-drain output that asserts immediately (<2µs) when PFI falls below threshold - providing asynchronous power-fail interrupt independent of the main reset timeout period.

Can MAX6728AKATGD3+T operate with VCC1 below 1.0V?

Yes, MAX6728AKATGD3+T guarantees valid reset output logic states with VCC1 or VCC2 ≥ 0.8V. However, the device ceases operation entirely below 0.8V. For applications requiring reset assertion down to 0V, a 100kΩ pulldown resistor on RST is recommended - though this only works with push-pull variants, not the open-drain RST in MAX6728AKATGD3+T.

What is the minimum pulse width required on the MR pin to trigger reset in MAX6728AKATGD3+T?

The MR pin on MAX6728AKATGD3+T requires a minimum low pulse width of 1µs to reliably initiate reset. The input includes 100ns glitch rejection, and the internal 50kΩ pullup to VCC1 allows MR to be left unconnected when unused. Reset remains asserted for the full 140ms timeout period after MR returns high.