Products Mentioned

LT8390 Recommended for New Designs
The LT8390 is a synchronous 4-switch buck-boost DC/DC controller that regulates output voltage, input or output current from an input voltage above, below...
Datasheet
LT8390 on Analog.com

LT8390A Recommended for New Designs
The LT8390A is a synchronous 4-switch buck-boost DC/DC controller that regulates output voltage, input or output current from an input voltage above, below...
Datasheet
LT8390A on Analog.com

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LT8390, LT8390A



		

			

									
					    kurt555
					
							

			
				
									
											
			
			
				
    
			
			
			    	
			                    
                
				                on Nov 27, 2022 
				
			
			
		
    

				
		
    
		    		    
		    
		    		      		            		        
    Category: Datasheet/Specs
    
    		        		            		    
    Product Number:  LT8390 
    
    		        		    		    	
			
    Hello!
    

    I am making a Buck-Boost Voltage Regulator using LT8390 or LT8390A.
    

    Comparing the typical applications listed in the datasheet of the LT8390 and LT8390A, in the case of the LT8390A, BST1 and BST2 are connected to INTVCC through a diode.
    

    I'd like to know why I should use a diode and what the problems would be if I didn't.
    

    

    Kind regards
    
									
			        
		
    

				
						
        

    
    Tags: 
                                            
                 Datasheet/Specs
                
                                                    
                 lt8390
                
                                                    
                 External Power Switch Buck-Boost Controllers
                
                                                    
                 Buck-Boost Regulators
                
                                                    
                 LT8390A
                
                                
            
    
    
    

		
    
			
						
									
									
						
						
			
			
			
			
		
    

        
        

					
    
			
    


    
















    
	
    
	
    
					



			








	
	
	
	



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							FormerMember
					
      
		
      
			
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									FormerMember
							        
			
			
			
    
            
						
                            
            
            				
            
                on Nov 28, 2022 1:02 AM
            
            
					
    
	
    

		
		
    
					
    Hello,
    

    The diode is used to block current coming back into the INTVCC. You should use diodes that are fast, typically schottky diodes are used as they have very good reverse recovery time, this should minimize the losses.
    

    

    Regards,
    

    Jhun
    
			
    

		
			
	      

		
		
	
    
	
    
		
    
			
		
    
	
    
	
    
		
						
						
				
						
				
				
		
		
    
			
		
    
	
    

    


	

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													0
							
			
				
									
							        
			
			
			
      
            
						
                            
            
            				
            
                on Nov 28, 2022 2:03 AM
            
            
												
						in reply to FormerMember
					
									
      
	
      

		
		
      
					
      Hello,
      

      Thank you for your reply.
      

      Please can you tell me what happens if I don't add a diode?
      

      Regards,
      
			
      

		
			
	      

		
		
	
      
	
      
		
      
			
		
      
	
      
	
      
		
						
						
				
						
				
				
		
		
      
			
		
      
	
      

      

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							FormerMember
					
      
		
      
			
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									FormerMember
							        
			
			
			
            
						
                            
            
            				
            
                on Nov 28, 2022 2:18 AM
            
            
												
						in reply to kurt555
					
									
      
	
      

		
		
      
					
      The current that returns to the Bias Supply might damage the bias, destroying your system.
      

      Read about how bootstrap circuit works. The diode also lets the Voltage on the High Side to be greater than the Bias in order to drive the top FET.
      
			
      

		
			
	      

		
		
	
      
	
      
		
      
			
		
      
	
      
	
      
		
						
						
						
						
				
				
		
		
      
			
		
      
	
      

      

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							FormerMember
					
        
		
        
			
													0
							
			
				
									FormerMember
							        
			
			
			
      
            
						
                            
            
            				
            
                on Nov 28, 2022 2:18 AM
            
            
												
						in reply to kurt555
					
									
      
	
      

		
		
      
					
      The current that returns to the Bias Supply might damage the bias, destroying your system.
      

      Read about how bootstrap circuit works. The diode also lets the Voltage on the High Side to be greater than the Bias in order to drive the top FET.
      
			
      

		
			
	      

		
		
	
      
	
      
		
      
			
		
      
	
      
	
      
		
						
						
						
						
				
				
		
		
      
			
		
      
	
      

      





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