Analog Devices Inc./Maxim Integrated MAX6368HKA29+

Overview

The MAX6368HKA29+ from Maxim Integrated is a low-power microprocessor supervisory circuit with auxiliary user-adjustable reset input, battery backup switching, and chip-enable gating. It monitors VCC supply voltage (reset threshold 2.85V–3.00V), provides active-high open-drain RESET output, operates down to 1.2V supply, draws only 10µA quiescent current, and supports CMOS RAM write protection in portable industrial controllers.

For engineers reviewing the MAX6368HKA29+ datasheet, MAX6368HKA29+ pinout, MAX6368HKA29+ application, or MAX6368HKA29+ equivalent, key selection criteria include its 1.235V internal reference for external reset threshold programming, 150ms minimum reset timeout, battery-switchover hysteresis, CE IN-to-CE OUT propagation delay under 9ns, and guaranteed RESET/RESET validity down to 1.2V during brownout.

Technical Context

The MAX6368HKA29+ implements a precision voltage comparator with 1.235V internal reference to monitor an externally programmed reset input (RESET IN), enabling secondary power-rail undervoltage detection. Its battery switchover logic enforces dual conditions: VCC must fall below both the factory-set 2.93V (typ) threshold *and* drop 20mV below VBATT before engaging backup mode.

Chip-enable gating uses a series transmission gate between CE IN and CE OUT, with 12µs reset-to-CE OUT delay and <9ns propagation delay (50Ω source, 50pF load). The open-drain active-high RESET output remains asserted for ≥150ms after RESET IN rises above threshold, ensuring reliable µP initialization during transient faults.

Key Specifications

Pinout & Package

MAX6368HKA29+ is housed in an 8-pin SOT23 package (2.9mm × 1.6mm × 1.1mm), optimized for space-constrained portable and industrial PCB layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6368HKA29+, MAX6368PKA29+ offers identical supervision functionality with simplified reset drive, while TPS3808G33DBVR trades advanced features (battery switchover, CE gating, adjustable reset input) for lower cost and power-making it viable only where those capabilities are unnecessary.

Availability

MAX6368HKA29+ is available at Aetrix Electronics and suitable for portable medical monitors, industrial PLC I/O modules, point-of-sale terminals, and smart energy meters requiring stable component supply and long-term lifecycle support.

Supply support for MAX6368HKA29+ 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, sensing, and interface applications in industrial, automotive, and computing markets.

The MAX6365–MAX6368 family was engineered to replace discrete reset, battery switchover, and memory protection circuits in space- and power-constrained µP systems-delivering integrated reliability in miniature SOT23 packages.

FAQ

What is the factory-set reset threshold voltage for MAX6368HKA29+?

The MAX6368HKA29+ has a factory-preset VCC reset threshold of 2.85V (min), 2.93V (typ), and 3.00V (max), optimized for reliable supervision of +3.0V microprocessor power rails. This threshold is laser-trimmed during production and does not require external components. The MAX6368HKA29+ maintains this specification across −40°C to +85°C operating temperature.

How does the RESET IN pin function on MAX6368HKA29+?

The RESET IN pin on MAX6368HKA29+ connects to an internal 1.235V precision reference comparator. When the voltage at RESET IN falls below 1.235V (1.185V min, 1.285V max), the device asserts the active-high RESET output. Its ±25nA leakage current allows use with high-value resistor dividers for monitoring secondary supplies like 5V or 12V rails without loading errors.

Does MAX6368HKA29+ support battery backup switching, and what are the engagement conditions?

Yes, MAX6368HKA29+ supports automatic battery backup switching. It engages backup mode only when two conditions are met simultaneously: VCC must fall below the 2.93V (typ) reset threshold *and* must be at least 20mV lower than VBATT. This dual-condition logic prevents false triggering during supply noise or slow VCC decay, ensuring reliable SRAM retention during actual power failures.

What is the purpose of the CE IN and CE OUT pins on MAX6368HKA29+?

The CE IN and CE OUT pins on MAX6368HKA29+ implement chip-enable signal gating to protect CMOS RAM from corruption during power faults. During normal operation, CE IN passes directly to CE OUT with ≤9ns delay. When reset asserts, CE OUT is forced low for 12µs (if CE IN was low) or held high (if CE IN was high), blocking erroneous writes to memory until the system stabilizes.

What output structure does MAX6368HKA29+ use for its RESET signal?

MAX6368HKA29+ uses an open-drain active-high RESET output. This configuration allows multiple devices to share a common reset bus (wired-OR), supports level translation across different voltage domains, and eliminates the need for a pull-up resistor when interfacing with µPs that provide internal pull-ups. The output sinks up to 20mA and remains valid down to 1.2V VCC or VBATT.