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Problems with the output LM25118

user5727960
Prodigy 40 points
Other Parts Discussed in Thread: LM25118
ello Community, Currently I am working with the chip LM25118 which outputs is fixed by a variable input voltage.
This function works perfectly when idling without load. For a load connection that needs a bit of power, the output voltage drops to a lower value than set.


Does anyone have any idea why this could be?















The oscilloscope image shows the voltage values ​​at the Rsense.






















This is the circuit for the board.
At the FB-pin is a potentiometer, so that the voltages 12 V and 24 V can be realized. (That is not Show in this circuit.)







 





								


				
				

				
			

		

			
						
									
                			    			                        
						
						
			
			
						
			                        
			
			
				
			  
			

			     
			

		


				    			

						
















	

	

					
    
	
    





		
	
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                          TI__Guru*
                        78190 points
                      
    
                          
                   		
		
    
					
    Hi user,
    

    
Thank you for your interests in LM25118.   It seems the current sense hit the peak current limit, mostly caused by noise picked  by the CS pin.  The CS and CSG traces should be routed closely side by side  over the entire lengths from the Rsense to the IC pins.  To see if this is issue, you can cut  the CS and CSG traces and use a pair of twisted wired to connect the Rsense to CS and CGS, and the issue should be resolved.
    

    
Thanks,
    
Youhao Xi,  Applications Engineering
    
			
    

		
		
		
		
	
    
	
    
		
    
			
		
    
	
    

	            
                 	
	
    
				
		                
                
                
                
                
                
                
        		
		
				
    
			
		
    
		
		 
		
		
     
    
	
    

    
			
    
			
    
		
    

		
    
	
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