How does Kelvin connection of PCB traces for current sensing help in accurate measurements? Or Why are the CSPx and CSNx nets routed as a pair?
Routing the Kelvin sense lines (separating lines for sensing signals from lines delivering power to loads) prevents noise related problems in a closed loop system as it allows for more accurate measurement of the sense voltage. In concept voltage developed across the sense resistor due to current is sensed and causes the current to constantly adjust in order to remain within tolerance. The voltage delta between the differential sense lines is often less than 100 mV, so 2 to 3 mV system noise can affect the sense accuracy by 5%.   Below picture shows how the sense lines from the sense resistor MUST NOT be connected. Below picture shows the correct layout. 其实"Kelvin Connector"还有更深层的含义，做早用于精确测量微电阻。请戳http://www.allaboutcircuits.com/vol_1/chpt_8/9.html