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ADP5071 Recommended for New Designs
The ADP5071 is a dual high performance dc-to-dc regulator that generates independently regulated positive and negative rails. The input voltage range of...
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ADP5071 on Analog.com

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Design Review - ADP5071 6V to +/-14V



		

			

									
					    Azone
					
							

			
				
									
											
			
			
				
    
			
			
			    	
			                    
                
				                on Aug 19, 2022 
				
			
			
		
    

				
		
    
		    		    
		    
		    		      		            		        
    Category: Hardware
    
    		        		            		    
    Product Number:  AD5071 
    
    		        		    		    	
			
    Hi,
    

    Please review the schematic if possible. I am only interested in the schematic at this time, not the layout. There are some discrepancies between the datasheet, eval board, and ADIsim tool in regards to compensation network, inductor values, and output voltage divider network resistor range. 
    

    1) I asked a question previously about compensation networks and was told to follow the sim tool instead of the datasheet - because it would be more accurate. Please confirm.
    

    2) Is there a sweet spot for the reference current for divider networks for setting the output voltages? The datasheet and eval show the values scaled up large (Mohms). The Sim tool gives much lower values. Please advise of either is preferable. 
    

    3) Any other thoughts welcome!
    

    AD5071 review 
    
									
			        
		
    

				
						
        

    
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      •  Analog Employees  
      
            
						
                            
            
            				
            
                on Aug 22, 2022 2:13 AM
            
            
					
      
	
      

		
		
      
					
      Hello Azone,
      

      The ADIsimPower tool considers a lot of design constraints, which is why we always recommend it to our customers. On the other hand, we also have recommended components on the datasheet for commonly used specifications of Vin and Vout.
      

      For the selection of feedback resistors, it is recommended that the current through the divider resistors is at least 10 times of Ifb1 or Ifb2 to limit the accuracy degradation of the output voltage (see page 17).
      

      May I know the estimated annual usage and the end application of this? Thank you.
      

      Regards, 
      

      Fritz Cyrill Gonzales
      
			
      

		
			
	      

		
		
	
      
	
      
		
      
			
		
      
	
      
	
      
		
						
						
				
						
				
				
		
		
      
			
		
      
	
      

      

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                on Aug 22, 2022 9:46 AM
            
            
												
						in reply to ADIApproved
					
									
        
	
        

		
		
        
					
        Thanks for the reply. Sounds good. We've already qualified the assembly but wanted more details before MP. The EAU is 500pcs. Thanks. I may share the layout as well. We did a 4-layer module and passed EMI for our application. 
        
			
        

		
			
	      

		
		
	
        
	
        
		
        
			
		
        
	
        
	
        
		
						
						
				
						
				
				
		
		
        
			
		
        
	
        

        

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        •  Analog Employees  
        
            
						
                            
            
            				
            
                on Aug 23, 2022 2:20 AM
            
            
												
						in reply to Azone
					
									
        
	
        

		
		
        
					
        Hi Azone, 
        

        I checked the connections on your schematic and it looks okay. Did you get the values of your components on the simPower tool? If so, then values should be okay. In addition to this, I recommend to put provision of unpopulated resistor across the SS pin to AGND and capacitor across the comp pin. The former is for soft start adjustment, while the latter is for adjustment of the compensation. You may need them later on your actual test, but these are just optional. You may still stick with what you have on your design right now.
        

        For the PCB layout, you may refer to the evaluation board of ADP5071 and the recommended layout on the datasheet. Kindly compare it with your layout and see if you missed something. Thank you.
        

        Regards, 
        

        Fritz
        
			
        

		
			
	      

		
		
	
        
	
        
		
        
			
		
        
	
        
	
        
		
						
						
						
						
				
				
		
		
        
			
		
        
	
        

        

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													0
							
			
				
									
							        
			
			
			
        •  Analog Employees  
        
            
						
                            
            
            				
            
                on Aug 23, 2022 2:20 AM
            
            
												
						in reply to Azone
					
									
        
	
        

		
		
        
					
        Hi Azone, 
        

        I checked the connections on your schematic and it looks okay. Did you get the values of your components on the simPower tool? If so, then values should be okay. In addition to this, I recommend to put provision of unpopulated resistor across the SS pin to AGND and capacitor across the comp pin. The former is for soft start adjustment, while the latter is for adjustment of the compensation. You may need them later on your actual test, but these are just optional. You may still stick with what you have on your design right now.
        

        For the PCB layout, you may refer to the evaluation board of ADP5071 and the recommended layout on the datasheet. Kindly compare it with your layout and see if you missed something. Thank you.
        

        Regards, 
        

        Fritz
        
			
        

		
			
	      

		
		
	
        
	
        
		
        
			
		
        
	
        
	
        
		
						
						
						
						
				
				
		
		
        
			
		
        
	
        

        

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