TOREX Semiconductor Ltd. has developed the XC6190 series of push button Reboot Controllers, designed to provide a system reboot signal to the controller used in small wearable devices. The chip itself measures just 1.3 mm square (USPN-6 outline) and is available in four variants.
The A variant only requires one external resistor to define the reboot delay timing between 1 s and 20 s while the B variant uses no resistor but can only generate a reboot delay of 7.5 s or 12.5 s depending on the state of the TS input.
For more detail: Torex Reboot Controller