The MAX6821MAX6825 are low-voltage microprocessor (P) supervisory circuits that combine voltage monitoring, watchdog timer, and manual reset input functions in a 5-pin SOT23 package. Microprocessor supervisory circuits significantly improve system reliability and accuracy compared to separate ICs or discrete components. These devices assert a reset signal whenever the monitored voltage drops below its preset threshold, keeping it asserted for a minimum timeout period after VCC rises above the threshold. In addition, a watchdog timer monitors against code execution errors. A debounced manual reset is also available. The MAX6821MAX6825 monitor voltages from +1.8V to +5.0V. These outputs are guaranteed to be in the correct state for VCC down to +1.0V. Nine preprogrammed reset threshold voltages are available (see Threshold Suffix Guide). The MAX6821, MAX6822, and MAX6823 all have a manual reset input and a watchdog timer. The MAX6821 has push-pull RESET, the MAX6822 has open-drain RESET, and the MAX6823 has push-pull RESET. The MAX6824 has a watchdog timer and both push-pull RESET and pushpull RESET. The MAX6825 has a manual reset input and both push-pull RESET and push-pull RESET. The Selector Guide explains the functions offered in this series of parts.