The watch dog circuit compares {TAIL ~ a second reference voltage} with a voltage exhibited by the first reset signal, and provides {HEAD ~ output} of a second reset signal to the controller to reset the controller in dependence upon the comparison between the second reference voltage and the voltage exhibited by the first reset signal 
The watch dog circuit compares { TAIL ~ a second reference voltage } with a voltage exhibited by the first reset signal , and provides { HEAD ~ output } of a second reset signal to the controller to reset the controller in dependence upon the comparison between the second reference voltage and the voltage exhibited by the first reset signal
OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH