Watchdog timer ICs (WDT) monitor whether or not the system operates normally by detecting periodical clock signals from an MCU.
They are also called supervisor IC, the same another name as voltage detectors (reset ICs) which detect supply voltage decrease.
If clock signals are not input within the timer period, the WDT judges that the system is under abnormal operation (or is going out of control), and outputs a reset signal.
There are two types of abnormality detection: the timeout type which detects abnormality by no signals within a certain period, and the window type which detects abnormality also by signals coming earlier than a certain cycle as well as no signals.
We have a wide lineup of WDTs featuring two types of clock input, a manual reset function (MR function), monitoring halt function by an INH pin, etc.
Besides, some of our products contain not only a WDT but also a voltage detector to monitor the supply voltage drop, and others incorporate an LDO regulator, a voltage detector, and a WDT in a single chip.