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LT3845A Recommended for New Designs
The LT3845A is a high voltage, synchronous, current mode controller used for medium to high power, high efficiency supplies. It offers a wide 4V to 60V...
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LT3845A on Analog.com

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Freewheeling Diode instead of bottom side mosfet

		
	
				

			

									
					    SteScre
					
							

            
            			
				
									
											
			
			
				
    
			
			
			    	
			                    
                
				                on Jan 20, 2026 
				
			
			
		
    
		
		                    	    
    
        	    
    Thread Summary
    
                The user inquired about replacing the bottom-side MOSFET with a Schottky diode in a buck converter using the LT3845A, aiming for space and cost reduction. The final answer confirmed that this is possible, with the diode's cathode connected to SW and the anode to ground, and the BG pin can be left floating. However, the BURST_EN pin must be grounded to disable burst mode, which is necessary for the diode replacement.
                        	    
    
                
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    Category: Hardware
    
    		        		            		    
    Product Number:  LT3845A  
    
    		        		    		    
    
		    		    
		    			
    
			    
    Dear All,
    

    I need an information about buck converter using LT3845A.
    

    In case of DC/DC converter with Vin=15V and Vout=3.3V@500mA, is it possible to replace the bottom side mosfet with a diode (leaving floating pin BG?
    

    This for space and cost reduction.
    

    

    Thanks in advance for your gently reply
    

    Stefano
    
			
    
			
									
		                             
                        

    
    
                                            
                 LT3845A
                
                                                    
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                 switching regulators
                
                                
            
    
    
    
		
    

				
				        
        		
    
			
						
									
												
			
			
                        
                                    
                        
                                                    
                        
            
			            
						
						
			
			
			
			
		
    

        
        
        
    
					
    
			
    


    
















    
	
    
	
    
					



			


				
	









	
      
	

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      •  Analog Employees  
      
            
						
                            
            
            				
            
                on Jan 23, 2026 5:44 AM
            
            
						
			            		
      
		
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      Hi Stefano, 
       
      Yes, you can run the LT3845A as a non-synchronous buck by replacing the MOSFET with a Schotty diode.  The cathode of the diode will be connected to SW and the Anode to the ground. You can leave the BG floating, as it will just act as an open load.

      Just ensure the BURST_EN pin is grounded in your schematic, which I am sure it is.
       
      
			
      

		
			
	      

		
		
	
      
	
      
		
      
			
		
      
	
      
	
      
		
						
				
						
				
				
				
		
		
      
			
		
      
	
      

      

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                on Jan 23, 2026 6:06 AM
            
            
						
			            		
        
		
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        Hi Anthonyuche, 
        

        thank you very much for your gently reply.
        

        Actually I connected the BURST_EN pin to Vcc, by analogy with the RH3845MK (which does not have the BURST function). This is in the case of future space applications.
        

        If I leave the BURST function disabled, is it not possible to replace the low MOSFET with a diode?
        

        Thanks in advance for your support.
        

        Kind Regards
        

        Stefano
        

        
			
        

		
			
	      

		
		
	
        
	
        
		
        
			
		
        
	
        
	
        
		
						
						
				
				
				
				
		
		
        
			
		
        
	
        

        

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                on Jan 23, 2026 6:07 AM
            
            
						
			            		
          
		
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          Hi Anthonyuche, 
          

          thank you very much for your gently reply.
          

          Actually I connected the BURST_EN pin to Vcc, by analogy with the RH3845MK (which does not have the BURST function). This is in the case of future space applications.
          

          If I leave the BURST function disabled, is it not possible to replace the low MOSFET with a diode?
          

          Thanks in advance for your support.
          

          Kind Regards
          

          Stefano
          
			
          

		
			
	      

		
		
	
          
	
          
		
          
			
		
          
	
          
	
          
		
						
						
				
				
				
				
		
		
          
			
		
          
	
          

          

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