Analog Devices Inc./Maxim Integrated MAX6366HKA44+T

Overview

MAX6366HKA44+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-high open-drain RESET on power failure or watchdog timeout, features 4.38V factory-set reset threshold, 150ms minimum reset timeout, and operates in 8-pin SOT23 for portable equipment requiring reliable µP reset and data retention during brownout.

For engineers reviewing the MAX6366HKA44+T datasheet, MAX6366HKA44+T pinout, MAX6366HKA44+T application, or MAX6366HKA44+T equivalent, key selection criteria include its 1.6s watchdog timeout, 4.38V reset threshold tolerance, battery-switchover hysteresis (±20mV), CE IN-to-CE OUT propagation delay (≤9ns), and guaranteed RESET/RESET operation down to 1.2V supply.

Technical Context

The MAX6366HKA44+T implements a precision voltage monitor with ±1.5% threshold accuracy over temperature, a monostable watchdog timer triggered by WDI edge transitions, and a bidirectional MOSFET-based VCC/BATT switchover path with 40mV hysteresis. Its internal 1.235V reference enables accurate reset assertion during VCC fall below 4.38V.

Chip-enable gating uses a transmission gate with 20Ω–100Ω on-resistance and ≤9ns propagation delay (50Ω source, 50pF load), while RESET output remains asserted for ≥150ms after VCC recovery. The device guarantees functional operation with VCC or VBATT as low as 1.2V, supporting ultra-low-voltage systems.

Key Specifications

Pinout & Package

Package: 8-pin SOT23 (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 MAX6366HKA44+T, MAX6366HKA46+T offers higher reset voltage for robustness in noisy 5V environments but reduces margin on 4.5V rails, while TPS3808G33DBVR provides lower-cost reset-only functionality at the expense of missing critical battery management and watchdog features required for data-retentive systems.

Availability

MAX6366HKA44+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 MAX6366HKA44+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, automotive, and computing applications.

The MAX6365–MAX6368 family was engineered specifically for µP systems needing coordinated reset, battery backup, and memory write protection-enabling compact, reliable solutions in space-constrained portable and industrial equipment.

FAQ

What is the exact reset threshold voltage of the MAX6366HKA44+T?

The MAX6366HKA44+T has a factory-preset reset threshold 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 specified in the Reset Threshold Ranges table of the datasheet. The MAX6366HKA44+T uses this precise threshold to initiate reset when VCC falls below the nominal +4.38V supply rail.

Does the MAX6366HKA44+T support both VCC and VBATT as valid operating supplies?

Yes, the MAX6366HKA44+T guarantees full functionality with either VCC or VBATT as low as 1.2V, including RESET assertion, watchdog operation, and CE gating. When VCC = 0V and VBATT ≥ 2.25V, the device remains active and switches OUT to battery power. This dual-supply capability ensures continuous supervision during main power failure, a core design requirement for the MAX6366HKA44+T.

How does the watchdog timer in the MAX6366HKA44+T respond to firmware hangs?

The MAX6366HKA44+T watchdog timer triggers a reset pulse if the WDI input remains static (high or low) for longer than 1.6s (typical). Each rising or falling edge on WDI resets the timer, so firmware must toggle WDI within this window-e.g., at subroutine entry/exit. If the firmware hangs, WDI stops toggling, the timer expires, and MAX6366HKA44+T asserts RESET for ≥150ms to force recovery.

Can the MAX6366HKA44+T be used without a backup battery?

Yes, the MAX6366HKA44+T operates fully without a backup battery: connect BATT to GND and tie OUT to VCC. In this configuration, it retains all core functions-VCC monitoring, 4.38V reset generation, 1.6s watchdog supervision, and CE gating-while disabling battery switchover. This makes the MAX6366HKA44+T suitable for cost-sensitive applications where data retention during power loss is not required.

What is the purpose of the CE IN and CE OUT pins on the MAX6366HKA44+T?

The CE IN and CE OUT pins implement hardware-enforced chip-enable gating: when reset is asserted, CE OUT is disconnected from CE IN to block spurious writes to SRAM or EEPROM. During normal operation, CE IN passes through to CE OUT with ≤9ns delay and 20Ω–100Ω on-resistance. This feature prevents memory corruption during power-up/down, making CE control an integral safety function of the MAX6366HKA44+T.