Analog Devices Inc./Maxim Integrated MAX6368PKA44+

Overview

MAX6368PKA44+ 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 (1.2V–5.5V), asserts active-low open-drain RESET when VCC falls below 4.38V (typ), provides 150ms minimum reset timeout, and supports 1.235V ±50mV RESET IN threshold for secondary supply monitoring. It is used in portable equipment requiring reliable power-fail detection and SRAM data retention.

For engineers reviewing the MAX6368PKA44+ datasheet, MAX6368PKA44+ pinout, MAX6368PKA44+ application, or MAX6368PKA44+ equivalent, key selection criteria include its 4.38V factory-set VTH, 1.235V RESET IN comparator reference, 8-pin SOT23 package, open-drain active-low RESET output, and integrated CE signal gating with 1.5ns propagation delay.

Technical Context

The MAX6368PKA44+ implements a precision voltage monitor with factory-trimmed 4.38V reset threshold (±0.125V over temperature), a dedicated 1.235V internal reference for external RESET IN threshold programming, and a bidirectional transmission gate for CE IN/CE OUT with 20Ω–100Ω on-resistance. Its battery switchover logic enforces dual conditions: VCC must be both below VTH and at least 20mV below VBATT to engage backup mode.

RESET assertion is triggered by VCC falling below 4.38V, RESET IN falling below 1.235V, or MR (if present) going low - but only MAX6368 variants support RESET IN; MR and WDI are excluded. The device guarantees RESET/RESET validity down to 1.2V VCC or VBATT and maintains <10µA quiescent current in normal operation.

Key Specifications

Pinout & Package

MAX6368PKA44+ is housed in an 8-pin SOT23 package (2.9mm × 1.6mm × 1.1mm), optimized for high-density portable designs. Pin assignments are validated per Maxim's official pin configuration diagram for MAX6368.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6367PKA44+, MAX6368PKA44+ trades BATT ON status signaling for programmable secondary-supply monitoring via RESET IN - enabling dual-rail fault detection in compact form factor. Against TPS3808G33DBVR, it adds critical features for data-retention systems: battery switchover, CE gating, and adjustable reset input - at higher quiescent current but essential for robust SRAM protection.

Availability

MAX6368PKA44+ is available at Aetrix Electronics and suitable for portable medical monitors, industrial PLC I/O modules, smart meter data loggers, and POS terminal memory backup systems requiring stable component supply, long-term lifecycle support, and guaranteed lead(Pb)-free compliance.

Supply support for MAX6368PKA44+ 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 high-performance analog, mixed-signal, and power-management ICs for industrial, automotive, and computing applications.

The MAX6365–MAX6368 family was designed specifically for microprocessor systems needing integrated power supervision, battery backup, and memory write protection - targeting space-constrained, battery-sensitive applications where reliability and low quiescent current are critical.

FAQ

What is the exact reset threshold voltage for MAX6368PKA44+?

The MAX6368PKA44+ has a factory-set reset threshold (VTH) of 4.38V (typical), with a guaranteed range of 4.25V to 4.50V across -40°C to +85°C. This value is laser-trimmed during production and applies to the VCC supply monitoring function - distinct from the 1.235V internal reference used for the RESET IN pin. The "44" suffix in the part number directly encodes this 4.38V nominal threshold per Maxim's ordering guide.

Does MAX6368PKA44+ support battery backup functionality?

Yes, MAX6368PKA44+ fully supports battery backup. When VCC falls below both the 4.38V reset threshold and VBATT by at least 20mV, the internal MOSFET switches OUT from VCC to BATT. It delivers up to 150mA from VCC and sustains SRAM operation in backup mode with <10µA quiescent current (VBATT = 2.8V). The device requires no external components for switchover and includes 40mV hysteresis to prevent oscillation during slow VCC decay.

What is the function of the RESET IN pin on MAX6368PKA44+?

The RESET IN pin on MAX6368PKA44+ is a dedicated auxiliary reset input that compares an external voltage to an internal 1.235V reference. When the voltage at RESET IN falls below 1.235V ±0.05V, the device asserts RESET. This enables precise undervoltage monitoring of secondary supplies (e.g., 5V, 3.3V) using a simple resistor divider - a feature absent in MAX6365/MAX6366/MAX6367 variants and critical for dual-rail system supervision.

What output type does MAX6368PKA44+ provide for the RESET signal?

MAX6368PKA44+ provides an open-drain active-low RESET output (denoted by "P" in the "PKA" suffix). This configuration allows wired-OR connection with other reset sources, level translation via external pull-up to any voltage ≤6V, and compatibility with µP reset inputs requiring active-low assertion. It differs from push-pull (L) and open-drain active-high (H) variants in the same family.

How does MAX6368PKA44+ protect memory during power failure?

MAX6368PKA44+ protects memory through two coordinated mechanisms: (1) Chip-enable (CE) gating - it disconnects CE IN from CE OUT within 1.5ns when RESET asserts, halting SRAM writes; and (2) Power switchover - it seamlessly transfers OUT from failing VCC to backup battery, maintaining SRAM VDD. Both functions operate simultaneously, ensuring data integrity even during rapid brownouts or complete VCC collapse.