Samsung S3F84A5 사용자 설명서

 

Buck circuit works when a switch signal turns on the transistor (Q). The DC power then starts to charge the coil 
(L). When the current reaches a predefined level, change the transistor state from On to Off using the switch 
signal. At this time, since the coil will have inertia to keep the current direction, the load still can be powered with a 
freewheeling diode until the switch signal turns on the transistor again. The resulting current is continuous but 
alternating (see 

 

 for more details). 

 

  The average current over load is determined by the duty cycle of switch signal. 
  SMPS can lead to current ripple. But it could be alleviated by increasing the PWM frequency or coil 

inductance value, or by adding extra filtering circuits.