Therefore, in accordance with the voltage level of {HEAD ~ the battery} 38 and bus 40, and by varying the duty cycle of {TAIL ~ a control signal} received by the SW1 and SW2, the battery 38 is either charged or discharged 
Therefore , in accordance with the voltage level of { HEAD ~ the battery } 38 and bus 40 , and by varying the duty cycle of { TAIL ~ a control signal } received by the SW1 and SW2 , the battery 38 is either charged or discharged
OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH