FB:Feedback Input. Error amplifier input for remote sensing of the output voltage. An external resistor between this pin and the output voltage sets the no load offset point.
CSREF:Current Sense Reference Voltage Input. The voltage on this pin is used as the reference for the current sense amplifier and the power-good and crowbar functions.
This pin should be connected to the common point of the output inductors
CSSUM:Current Sense Summing Node. External resistors from each switch node to this pin sum the average inductor currents together to measure the total output current.
CSCOMP:Current Sense Compensation Point. A resistor and capacitor from this pin to CSSUM determines the gain of the current sense amplifier and the positioning loop response time.
以上可看出四者的作用及關係:D