The pump down circuit may be configured to generate {HEAD ~ a pump} down {TAIL ~ signal} in response to the pump up signal and the control signal 
down
The pump down circuit may be configured to generate { HEAD ~ a pump } down { TAIL ~ signal } in response to the pump up signal and the control signal
OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH