a resistor connected to the current feedback input of the PWM generator and {HEAD ~ current compensation IC}, the electronic switch and {TAIL ~ ground} 
a resistor connected to the current feedback input of the PWM generator and { HEAD ~ current compensation IC } , the electronic switch and { TAIL ~ ground }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL