Analog Devices Inc./Maxim Integrated MAX6368LKA26+T

Overview

The MAX6368LKA26+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 operates from 1.2V to 5.5V, features a factory-preset 2.63V reset threshold (±70mV), guarantees RESET assertion down to 1.2V supply, delivers 150ms minimum reset timeout, and supports CMOS RAM protection in portable industrial controllers.

For engineers reviewing the MAX6368LKA26+T datasheet, MAX6368LKA26+T pinout, MAX6368LKA26+T application, or MAX6368LKA26+T equivalent, key selection criteria include its 1.235V internal reference for external voltage monitoring, 1.5µs RESET IN to reset propagation delay, open-drain active-high RESET output, 8-pin SOT23 package, and guaranteed operation across –40°C to +85°C.

Technical Context

The MAX6368LKA26+T integrates a precision comparator for RESET IN (1.235V ±50mV reference), a VCC-to-OUT power switch with 4.6Ω on-resistance at 2.38V, and a chip-enable transmission gate with 1.5ns typical propagation delay. Its battery switchover logic requires both VCC < VTH and VCC < VBATT − 20mV before engaging backup mode.

RESET is an open-drain active-high output asserted continuously during VCC brownout, RESET IN undervoltage, or after watchdog timeout (though MAX6368 lacks watchdog). CE OUT is actively pulled up to OUT when disconnected, and CE IN to CE OUT resistance is 20–100Ω when reset is deasserted.

Key Specifications

Pinout & Package

MAX6368LKA26+T is housed in an 8-pin SOT23 package (2.9mm × 1.6mm × 1.1mm), surface-mount, lead(Pb)-free, RoHS-compliant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6368PKA26+T, the MAX6368LKA26+T provides flexible reset bus interfacing via open-drain output, while TPS3808G125DBVR offers lower cost and smaller footprint but omits critical battery-switchover and RESET IN functions required for data retention systems.

Availability

MAX6368LKA26+T is available at Aetrix Electronics and suitable for portable medical devices, industrial PLC modules, battery-backed data loggers, and secure POS terminals requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MAX6368LKA26+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, mixed-signal, and power management ICs for demanding industrial, automotive, and computing applications.

The MAX6365–MAX6368 family targets space-constrained µP systems needing integrated power supervision, battery backup, and memory write protection - specifically engineered for reliability in portable and harsh-environment equipment.

FAQ

What is the function of the RESET IN pin on the MAX6368LKA26+T?

The RESET IN pin on the MAX6368LKA26+T is an auxiliary reset input compared against an internal 1.235V reference. When the voltage at RESET IN falls below this threshold, the device asserts its open-drain active-high RESET output. This enables precise monitoring of secondary power rails-such as a 4.6V analog supply-using an external resistor divider. The MAX6368LKA26+T guarantees a 1.5µs propagation delay from RESET IN transition to RESET assertion, supporting fast fault response in safety-critical systems.

Does the MAX6368LKA26+T support battery backup switchover, and what are the conditions?

Yes, the MAX6368LKA26+T supports automatic battery backup switchover. It connects the BATT input to the OUT pin only when two simultaneous conditions are met: VCC must fall below the factory-preset 2.63V reset threshold, and VCC must also be at least 20mV lower than VBATT. This 40mV hysteresis prevents oscillatory switching during slow VCC decay. In backup mode, the device draws just 3µA from the battery (excluding load current), enabling multi-year operation with standard coin cells. The MAX6368LKA26+T does not power up from BATT alone-it requires initial VCC presence at startup.

What output structure does the MAX6368LKA26+T use for its RESET signal?

The MAX6368LKA26+T uses an open-drain active-high RESET output. This means the RESET pin remains high-impedance (floating) when deasserted and pulls to GND only when actively asserting reset. An external pull-up resistor is required to establish the high state-typically to VCC or another logic rail. This architecture enables wired-OR connection of multiple reset sources on a shared bus and supports level translation across different voltage domains. Unlike push-pull versions (e.g., MAX6368PKA26+T), the LKA variant cannot actively drive high, making it ideal for systems requiring reset arbitration or mixed-voltage interfaces.

How does chip-enable gating work on the MAX6368LKA26+T, and what is its timing behavior?

The MAX6368LKA26+T gates the CE IN signal to CE OUT using a low-on-resistance transmission gate (20–100Ω). During normal operation, CE IN passes directly to CE OUT with 1.5ns typical propagation delay. When reset asserts, CE OUT is immediately held low for 12µs to complete any ongoing memory read/write cycle-even if CE IN transitions high during that time. After 12µs, CE OUT is actively pulled up to OUT. This behavior prevents data corruption in SRAM during power faults. The MAX6368LKA26+T's CE gating is fully integrated, eliminating the need for external logic or MOSFETs in memory protection circuits.

What is the guaranteed operating temperature range and supply voltage range for the MAX6368LKA26+T?

The MAX6368LKA26+T is specified for continuous operation from –40°C to +85°C ambient temperature and supports supply voltages from 1.2V to 5.5V on both VCC and VBATT pins. Its RESET output remains valid down to 1.2V supply-ensuring reliable reset assertion even during deep brownout conditions. The device's internal circuitry, including the 1.235V RESET IN reference and reset timer, is characterized across this full range. This makes the MAX6368LKA26+T suitable for industrial and automotive-adjacent applications where thermal stress and wide input voltage variation are common design constraints.