Maxim Integrated's MAX708SESA Microprocessor Supervisory Circuit

The MAX708SESA from Maxim Integrated is a compact, highly efficient microprocessor (µP) supervisory circuit designed to monitor power supplies in µP and digital systems. It provides excellent circuit reliability and low cost by eliminating external components and adjustments when used with +5V-powered circuits.

This supervisory circuit is particularly well-suited for use in computers, controllers, intelligent instruments, and critical µP power monitoring applications. Its primary function is to assert a reset signal to the µP whenever the VCC supply voltage declines below a preset threshold, ensuring that the µP starts up in a known state. The reset signal remains asserted until the VCC supply voltage returns to an acceptable level and after a preset timeout period has elapsed, allowing the power supply and µP to stabilize.

Key features of the MAX708SESA include:

• Reset Timeout: It offers a factory-trimmed reset timeout delay of 200ms, ensuring that the system has adequate time to recover before the µP resumes operation.
• Manual Reset Input: A manual reset input is provided, allowing for a reset to be triggered with an external switch or logic signal.
• Watchdog Timer: A watchdog timer is built-in, which must be periodically cleared by the µP. If not cleared, the MAX708SESA asserts a reset signal, providing an additional layer of system reliability.
• Voltage Monitor: The supervisory circuit monitors the supply voltage and asserts a reset if the supply voltage drops below the threshold, which is factory preset to 4.63V for the MAX708SESA.
• Low Power Consumption: It is designed for low power consumption, which is critical for battery-powered applications.
• Compact Package: The device is available in a space-saving 8-pin SO package, making it suitable for use in systems where space is at a premium.

The MAX708SESA supervisory circuit is an essential component for system stability, providing critical monitoring and control functions to ensure that digital systems operate reliably. Its integration of several supervisory functions into a single chip makes it an economical choice for a wide range of applications.