Analog Devices Inc./Maxim Integrated MAX6366PKA44-T

Overview

The MAX6366PKA44-T from Maxim Integrated is a low-power microprocessor supervisory circuit with integrated watchdog timer, battery-backup switchover, and chip-enable gating. It monitors VCC supply (1.2V–5.5V), asserts active-low open-drain RESET on power-up/down/brownout or watchdog timeout, provides 1.6s watchdog timeout, supports 4.38V factory-set reset threshold, and maintains CMOS RAM during main supply failure in portable and industrial µP systems.

For engineers reviewing the MAX6366PKA44-T datasheet, MAX6366PKA44-T pinout, MAX6366PKA44-T application, or MAX6366PKA44-T equivalent, key selection criteria include its 1.6s watchdog timeout, 4.38V reset threshold tolerance, 10µA quiescent current, SOT23-8 package compatibility, and support for battery-backed memory write protection in space-constrained embedded designs.

Technical Context

The MAX6366PKA44-T implements a dedicated watchdog timer with 1.00–2.25s timeout range (typ. 1.6s), triggered by WDI edge transitions and cleared on reset assertion or WDI state change. Its internal reset generator guarantees RESET assertion for ≥150ms after VCC rises above 4.38V, while maintaining valid logic levels down to 1.2V supply.

Battery switchover uses a MOSFET-based VCC/BATT selector with 40mV hysteresis and <1µA standby current in backup mode. Chip-enable gating provides 1.5ns propagation delay and 20–100Ω on-resistance between CE IN and CE OUT, disabled during reset to prevent SRAM corruption.

Key Specifications

Pinout & Package

MAX6366PKA44-T is housed in an 8-pin SOT23 package (2.9mm × 1.6mm, 0.95mm height), optimized for high-density PCB layouts and reflow-compatible assembly.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6366HKA44-T and TPS3808G33DBVR, the MAX6366PKA44-T uniquely combines open-drain reset flexibility, integrated watchdog supervision, and battery-backed memory protection in a single SOT23-8 device-enabling compact, fail-safe µP systems where power continuity and firmware reliability are critical.

Availability

MAX6366PKA44-T 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 MAX6366PKA44-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 interface applications in industrial, automotive, and communications markets.

The MAX6365–MAX6368 family delivers ultra-low-power supervisory functions-including watchdog, battery switchover, and chip-enable gating-for space-constrained microprocessor systems demanding high reliability under variable power conditions.

FAQ

What is the exact reset threshold voltage of the MAX6366PKA44-T?

The MAX6366PKA44-T has a factory-trimmed reset threshold of 4.38V, with a guaranteed range of 4.25V (min) to 4.50V (max) across temperature and process variation. This value is permanently laser-trimmed during manufacturing and does not require external resistor programming. The threshold remains stable over -40°C to +85°C operation and is specified in the Electrical Characteristics table of the MAX6366PKA44-T datasheet.

Does the MAX6366PKA44-T support battery backup for SRAM, and how does it switch?

Yes, the MAX6366PKA44-T supports battery backup for SRAM via its integrated VCC/BATT switchover circuit. When VCC falls below the 4.38V reset threshold and VBATT exceeds VCC by at least 20mV, the internal MOSFET connects BATT to the OUT pin, powering SRAM from the backup source. The 40mV hysteresis prevents oscillation during slow VCC decay. In battery-backup mode, MAX6366PKA44-T draws <1µA from BATT (excluding load current) to maximize backup runtime.

What is the function of the WDI pin on the MAX6366PKA44-T, and how should it be driven?

The WDI (Watchdog Input) pin on the MAX6366PKA44-T resets the internal 1.6s watchdog timer on any rising or falling edge. To prevent spurious timeouts, firmware must toggle WDI at least once every 1.6s - typically by pulsing it low then high within a subroutine loop. The pin accepts TTL/CMOS logic levels (VIH = 0.7×VCC, VIL = 0.3×VCC), tolerates 100ns minimum pulse width, and draws ±1.0µA input current. Leaving WDI unconnected disables the watchdog function.

Can the MAX6366PKA44-T be used without a backup battery?

Yes, the MAX6366PKA44-T operates fully without a backup battery. In this configuration, connect the BATT pin to GND and route VCC directly to the OUT pin. The device continues to provide VCC monitoring, 4.38V reset generation, 1.6s watchdog supervision, and chip-enable gating. All core supervisory functions remain active; only battery switchover and backup power delivery are disabled. This setup is common in cost-sensitive or non-critical applications where data retention during power loss is not required.

What is the purpose of the CE IN and CE OUT pins on the MAX6366PKA44-T?

The CE IN and CE OUT pins on the MAX6366PKA44-T implement hardware-enforced chip-enable gating to prevent SRAM corruption during power faults. CE IN connects to the µP's chip-enable signal; CE OUT drives the SRAM's CE input. During normal operation, the path is transparent (1.5ns delay). When RESET asserts, CE OUT is immediately disabled - holding low for 12µs if CE IN was low at assertion time, then pulled high to OUT. This blocks all CE transitions during reset, ensuring no partial memory writes occur.