Products Mentioned

ADD5211 Not Recommended for New Designs
The ADD5211 is a four-string, white LED driver for backlight applications based on high efficiency, current mode, step-up converter technology. The boost...
Datasheet
ADD5211 on Analog.com

Thread Details

  • State Verified Answer
  • Replies 1 reply
  • Subscribers 39 subscribers
  • Views 714 views
  • Users 0 members are here
Options 

        

            Post
             Go back to editing
        

    

    


    

    









		


















	
	
			
	
			
		
	
	
		

	    
	    
	    		
ADD5211 Cout,inductor scream issue

		
	
				

			

									
					    Verti
					
							


			
				
									
											
			
			
				
    
			
			
			    	
			                    
                
				                on Feb 21, 2019 
				
			
			
		
    
		
		                     
				
        		
    
		    
		    		    
		    			
    
			    
    Good day,
    

             We use ADD5211  for four-string LED driving, input voltage is 12v, output voltage is 20.4v/89mA per string.
    

    All parameters follow the datasheet and tool guidance, ADD5211 can delight the LEDs but scream issue happen with Cin, Cout and boost Inductor. We try to increase the Cout value and adjust the comp circuit, still can not solve this issue. Can you kindly help to advice or share the debug experience about this chip, thank you.
    

    Below is the schematic.
    

     
    
			
    
			
									    
    
			        
    Edit Notes
    
    				none
    
[edited by: Verti at 8:41 AM (GMT 0) on 21 Feb 2019]
				
    
						
		                             
                        

    
    
                                            
                 Step-Up (Boost) LED Drivers
                
                                                    
                 add5211
                
                                                    
                 LED Driver IC
                
                                
            
    
    
    
		
    

				
				        
        		
    
			
						
									
												
			
			
                        
                                    
                        
                                                    
                        
            
			            
						
						
			
			
			
			
		
    

        
        
        
    
					
    
			
    


    
















    
	
    
	
    
					



			








	
	
	
	



Parents
	
      
	

    • 
	
      



	
			
		
	



      
	
      
		
      
							
					
      
		
      
			
				
									
							        
			
			
			
      •  Analog Employees  
      
            
						
                            
            
            				
            
                on Mar 7, 2019 12:10 AM
            
            
						
			            		
      
		
										0
					
	
      

		
		
      
		
      
                                
                                                            
      
					
      the MLCC capacitor has the piezoelectric effect, which may cause the noise (scream) on the capacitor, could you replace the capacitor with other vendors capacitor or another type of capacitor to check if the issue gone?
      

      

      for the inductor, the vibration of the wind also will cause the scream. if the noise is coming from the inductor, please change another inductor and see if issue goes ( you can use flat winding inductors )
      
			
      

		
			
	      

		
		
	
      
	
      
		
      
			
		
      
	
      
	
      
		
						
						
						
				
				
				
		
		
      
			
		
      
	
      

      

      • 

	
    



Reply

      


    • 
	
      



	
			
		
	



      
	
      
		
      
							
					
      
		
      
			
				
									
							        
			
			
			
      •  Analog Employees  
      
            
						
                            
            
            				
            
                on Mar 7, 2019 12:10 AM
            
            
						
			            		
      
		
										0
					
	
      

		
		
      
		
      
                                
                                                            
      
					
      the MLCC capacitor has the piezoelectric effect, which may cause the noise (scream) on the capacitor, could you replace the capacitor with other vendors capacitor or another type of capacitor to check if the issue gone?
      

      

      for the inductor, the vibration of the wind also will cause the scream. if the noise is coming from the inductor, please change another inductor and see if issue goes ( you can use flat winding inductors )
      
			
      

		
			
	      

		
		
	
      
	
      
		
      
			
		
      
	
      
	
      
		
						
						
						
				
				
				
		
		
      
			
		
      
	
      

      

      • 


    


Children
	
    No Data