a first voltage monitor coupled to a first voltage source at a first input and a first threshold voltage at a second input, {HEAD ~ the first voltage source} operable at a pair of {TAIL ~ voltages}, one voltage higher than the second voltage, 
a first voltage monitor coupled to a first voltage source at a first input and a first threshold voltage at a second input , { HEAD ~ the first voltage source } operable at a pair of { TAIL ~ voltages } , one voltage higher than the second voltage ,
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH