The STM809/810/811/812 MICROPROCESSOR RESET Circuits are low-power supervisory devices used to monitor power supplies. They perform a single function: asserting a reset signal whenever the VCCsupply voltage drops below a preset value and keeping it asserted until VCChas risen above the preset threshold for a minimum period of time (trec). The STM811/812 also provide a push-button reset input (MR).