Low-Voltage SOT23 µP Supervisors with Manual Reset and Watchdog Timer

The MAX6821—MAX6825 are low-voltage microprocessor (µP) 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 MAX6821—MAX6825 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 the 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 active-low RESET, and the MAX6823 has push-pull active-low RESET. The MAX6824 has a watchdog timer and both push-pull active-low RESET and push-pull RESET. The MAX6825 has a manual reset input and both push-pull active-low RESET and push-pull RESET. The Selector Guide explains the functions offered in this series of parts.

Applications

* Computers and Controllers * Critical µP Monitoring * Embedded Controllers * Intelligent Instruments * Portable Battery-Powered Equipment * Set-Top Boxes

* Monitors +1.8V, +2.5V, +3.0V, +3.3V, +5.0V Supplies

* 140ms (min) Reset Timeout Delay

* 1.6s Watchdog Timeout Period (MAX6821/MAX6822/MAX6823/MAX6824)

* Manual Reset Input (MAX6821/MAX6822/MAX6823/MAX6825)

* Three Reset Output Options

* Push-Pull Active-Low RESET

* Push-Pull RESET

* Open-Drain Active-Low RESET

* Guaranteed Reset Valid to VCC = +1.0V

* Immune to Short Negative VCC Transients

* No External Components

* Small 5-Pin SOT23 Packages