Analog Devices Inc./Maxim Integrated MAX6368HKA31+T

Overview

The MAX6368HKA31+T from Maxim Integrated is a low-power microprocessor supervisory circuit with auxiliary user-adjustable reset input, battery-backup switchover, and chip-enable gating. It monitors VCC supply voltage (reset threshold = 3.08V typ), asserts active-low open-drain RESET during power-up/down/brownout, switches OUT between VCC and backup battery (VBATT), and gates CE signals with 1.5ns propagation delay. Used in portable equipment requiring reliable memory write protection during power failure.

For engineers reviewing the MAX6368HKA31+T datasheet, MAX6368HKA31+T pinout, MAX6368HKA31+T application, or MAX6368HKA31+T equivalent, key selection criteria include its 3.08V factory-set reset threshold, 1.235V auxiliary RESET IN comparator, 150ms minimum reset timeout, 10µA quiescent current, and SOT23-8 package compatibility with space-constrained µP systems.

Technical Context

The MAX6368HKA31+T integrates four core functions: precision VCC monitoring with ±1.5% threshold accuracy over temperature, automatic VCC-to-BATT switchover when VCC falls below VBATT by >20mV, internal chip-enable gating that disables CE signal paths during reset to prevent SRAM corruption, and a dedicated RESET IN comparator referenced to 1.235V for secondary supply monitoring.

Its RESET output is open-drain active-low (MAX636_H variant), asserted continuously when VCC < 3.08V or RESET IN < 1.235V, and held for ≥150ms after recovery. The CE IN-to-CE OUT path uses a transmission gate with 20–100Ω on-resistance and 12µs reset-to-CE OUT delay, enabling use with high-speed µPs and DSPs without timing violation.

Key Specifications

Pinout & Package

Package: 8-pin SOT23 (2.9mm × 1.6mm × 1.1mm), lead(Pb)-free, tape-and-reel.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar microprocessor supervisory applications.

Compared with MAX6368HKA31+T, the PKA31 variant offers lower component count in single-load designs but sacrifices bus-sharing flexibility, while the TPS3808G33DBVR reduces quiescent current by 70% but omits critical battery-backup and dual-threshold functionality required for data retention systems.

Availability

MAX6368HKA31+T is available at Aetrix Electronics and suitable for portable medical devices, industrial PLC modules, point-of-sale terminals, and set-top box firmware storage requiring stable component supply and long-term lifecycle support.

Supply support for MAX6368HKA31+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 power management, sensing, and connectivity in demanding industrial and automotive environments.

The MAX6365–MAX6368 family delivers integrated µP supervision with battery backup and CE gating, targeting space-constrained embedded systems needing guaranteed data integrity during power faults.

FAQ

What is the exact reset threshold voltage for MAX6368HKA31+T?

The MAX6368HKA31+T has a factory-trimmed reset threshold of 3.00V (min), 3.08V (typ), and 3.15V (max) at TA = +25°C, with ±1.5% variation over -40°C to +85°C. This 3.08V nominal threshold is optimized for reliable detection of brownout conditions on 3.3V logic rails, ensuring the MAX6368HKA31+T asserts reset before µP operation becomes unstable.

How does the RESET IN pin function on MAX6368HKA31+T?

The RESET IN pin on MAX6368HKA31+T connects to an internal 1.235V comparator. When the voltage at RESET IN falls below 1.235V (±50mV), the MAX6368HKA31+T asserts active-low RESET. This enables monitoring of secondary supplies-e.g., using a resistor divider to detect failure of a 5V analog rail at 4.60V-without adding external comparators or voltage references.

What package type and dimensions does MAX6368HKA31+T use?

The MAX6368HKA31+T is supplied in an 8-pin SOT23 package measuring 2.9mm × 1.6mm × 1.1mm, with lead(Pb)-free terminations and tape-and-reel packaging (2500 units per reel). Its small footprint and thermal performance support high-density PCB layouts in portable and industrial edge devices where the MAX6368HKA31+T operates reliably from -40°C to +85°C.

Does MAX6368HKA31+T support battery-backup switchover, and what are the conditions?

Yes, the MAX6368HKA31+T automatically switches OUT from VCC to BATT when two conditions are met: VCC falls below the 3.08V reset threshold AND VCC drops at least 20mV below VBATT. A 40mV hysteresis prevents oscillation during slow VCC decay. In backup mode, the MAX6368HKA31+T draws only 3µA from the battery (IBACK), sustaining SRAM data for years.

What is the purpose of CE IN and CE OUT pins on MAX6368HKA31+T?

The CE IN and CE OUT pins implement chip-enable signal gating: CE IN accepts the µP's chip-enable signal, and CE OUT delivers a gated version to external memory. During normal operation, CE IN passes through to CE OUT with 1.5ns delay. When RESET asserts, CE OUT is disabled-preventing spurious writes to SRAM during power transitions. This function is integral to the MAX6368HKA31+T's role in data-critical embedded systems.