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LTC4411 - Schottky diode selection for automatic power switch over



		

			

									
					    jlittle
					
							

			
				
									
											
			
			
				
    
			
			
			    	
			                    
                
				                on Aug 7, 2019 
				
			
			
		
    

				
		
    
		    		    
		    
		    	
			
    I'm in the process of designed a simple power supply OR switch using the LTC4411.  The main supply is regulated 3.3V from a battery while the secondary source is a regulated 3.3V supplied via a 12V wall adapter. 
    

    I have trouble properly selecting the schottky diode that is recommended in the applications notes from the data sheet.
    

    Thanks
    
								
    

				
				
		
    
			
						
									
									
						
						
			
			
			
			
		
    

        
        

					
    
			
    


    


	















    
	
    
	
    
					



			








	
	
	
	



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      •  Analog Employees  
      
            
			                            
                        
                on Aug 20, 2019 12:01 AM
            
            
					
      
	
      

		
		
      
					
      Hi,  The Schottky diode needs to have a reverse breakdown greater than 3.3V (plus margin) and should be rated for your load current. Note that a 0.3V or 0.5V Schottky diode drop can eat up a significant portion of your 3.3V supply (10% to 15%). It may be better to use the LTC4413 dual ideal diode for your application.
      
			
      

		
		
		
		
	
      
	
      
		
      
			
		
      
	
      
	
      
		
						
				
						
						
				
				
		
		
      
			
		
      
	
      

      

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      •  Analog Employees  
      
            
			                            
                        
                on Aug 20, 2019 12:01 AM
            
            
					
      
	
      

		
		
      
					
      Hi,  The Schottky diode needs to have a reverse breakdown greater than 3.3V (plus margin) and should be rated for your load current. Note that a 0.3V or 0.5V Schottky diode drop can eat up a significant portion of your 3.3V supply (10% to 15%). It may be better to use the LTC4413 dual ideal diode for your application.
      
			
      

		
		
		
		
	
      
	
      
		
      
			
		
      
	
      
	
      
		
						
				
						
						
				
				
		
		
      
			
		
      
	
      

      

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