Maxim Integrated MAX691AESE+T Microprocessor Supervisory Circuit

The MAX691AESE+T from Maxim Integrated is an advanced microprocessor (µP) supervisory circuit designed to monitor power supplies and microprocessor activity in digital systems. It provides excellent circuit reliability and low cost by eliminating external components and adjustments when used in conjunction with +5V-powered circuits.

This supervisory circuit significantly enhances system reliability by providing several key protection features to ensure the proper operation of the microprocessor. It monitors the power supply voltage and maintains a reset output to the microprocessor for a minimum of 140ms after VCC has reached the operating threshold. This ensures that the µP starts up in a known state every time the power is applied.

Additionally, the MAX691AESE+T has a watchdog timer that must be periodically reset by the microprocessor within a set time frame. If the µP fails to reset the watchdog circuit within that time, the MAX691AESE+T will issue a system reset, thereby providing a fail-safe for systems that lock up due to software or hardware faults.

The device also features a battery backup switching function that automatically switches to a backup battery when the main power supply fails, ensuring that critical data is preserved. The chip-select gating function ensures that the µP's memory is in the write-protect state during power-up, power-down, and reset, preventing any erroneous writes to the memory.

Designed in a 16-pin narrow SO package, the MAX691AESE+T is easy to integrate into a variety of systems. It's ideal for use in microprocessor systems, computers, controllers, intelligent instruments, critical µP power monitoring, and portable battery-powered equipment.

Overall, the MAX691AESE+T supervisory circuit is a versatile and reliable solution for enhancing system integrity. Its combination of reset, watchdog, and backup battery functionalities make it an invaluable component for any microprocessor-based system that requires robust protection against power failures and operational errors.