When the input voltage {HEAD ~ VIN} 602 is much lower than the output voltage VOUT 604, {TAIL ~ the buck boost converter} is running in a pure boost mode of operation 
When the input voltage { HEAD ~ VIN } 602 is much lower than the output voltage VOUT 604 , { TAIL ~ the buck boost converter } is running in a pure boost mode of operation
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH