Maxim Integrated MAX823T Microprocessor Supervisory Circuit

The MAX823T from Maxim Integrated is a precision microprocessor (µP) supervisory circuit designed to monitor power supplies in digital systems. It provides excellent circuit reliability and low cost by eliminating external components and adjustments when used with 5V-powered circuits. This compact supervisory IC is ideal for monitoring 3.3V and 5V power supplies in a wide range of electronic applications, including computers, controllers, and intelligent instruments.

The MAX823T features a combination of functionalities that ensure system integrity. It offers a reset output during power-up, power-down, and brownout conditions. The reset signal is asserted when the VCC supply voltage falls below the reset threshold, keeping it asserted for at least 140ms after VCC has risen above the reset threshold, ensuring a proper system reset. This feature allows the connected microprocessor to reset to a known state during power disturbances.

Additionally, the MAX823T incorporates a watchdog timer that monitors the connected microprocessor or microcontroller, providing an additional layer of system reliability. If the microprocessor fails to provide a watchdog pulse within a preset timeout period, the MAX823T generates a system reset, thereby preventing system hangs and ensuring reliable operation.

This supervisory circuit is available in a compact SOT23-5 package, making it suitable for space-constrained applications. Its low power consumption and wide supply voltage range make it versatile for use in portable and battery-powered devices. With its built-in glitch immunity, the MAX823T ensures that voltage transients on VCC do not result in false resets, providing stable operation even in electrically noisy environments.

Key features of the MAX823T include:

• Reset threshold options suitable for 3.3V and 5V power supplies
• Minimum 140ms reset timeout period
• Watchdog timer with a 1.6s timeout period
• Low supply current of 17µA (typical) for energy efficiency
• Guaranteed reset valid to VCC = 1V for low-voltage operation
• Immunity to short VCC transients

Overall, the Maxim Integrated MAX823T is a robust and reliable solution for system monitoring, offering protection against power supply anomalies and ensuring consistent operation of electronic systems.