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AD7616 Production
The AD7616 is a 16-bit, DAS that supports dual simultaneous sampling of 16 channels. The AD7616 operates from a single 5 V supply and can accommodate Â...
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AD7616 on Analog.com

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Do I need to use resistor when grounding unused parallel lines (Dx).

		
	
				

			

									
					    Andy79881
					
							

            
            			
				
									
											
			
			
				
    
			
			
			    	
			                    
                
				                on Oct 23, 2025 
				
			
			
		
    
		
		                     
				
        		
    
		    
		    		    
    
		      		            		        
    Category: Datasheet/Specs
    
    		        		            		    
    Product Number:  AD7616  
    
    		        		    		    
    
		    		    
		    			
    
			    
    Hello,
    

    basically we would like to know if we can dierectly tie the parallel lines (Dx) in serial mode. Datasheet says : "In serial mode, these pins must be tied to DGND." (e.g. for DB0, 1, 2 3). The question raised up, since DBx pins are of DO/DI type is there a possibility that the pins are actively driven even if ADC is configured in Serial Mode (SER/PAR* tied to +3.3V).
    

    Q1:Can we directly tie the pins to DGND without any series resistors?
    

    Q2: If for safe operation resistors are required: what is the proposed value range?
    

    

    Regards Andreas
    
			
    
			
									
		                             
                        

    
    
                                            
                 Datasheet/Specs
                
                                                    
                 Simultaneous Sampling A/D Converters
                
                                                    
                 ad7616
                
                                                    
                 Precision A/D Converters
                
                                
            
    
    
    
		
    

				
				        
        		
    
			
						
									
												
			
			
                        
                                    
                        
                        
                        
            
			            
						
						
			
			
			
			
		
    

        
        
        
    
					
    
			
    


    
















    
	
    
	
    
					



			


				
	









	
      
	

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      •  Analog Employees  
      
            
						
                            
            
            				
            
                on Oct 23, 2025 9:51 AM
            
            
						
			            		
      
		
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      Hello,
      

      The recommendation from the datasheet is to tied them directly to DGND. In the eval board we used 100k pull-down resistors, which in the case of selecting SER interface is like a series resistor to ground. If that helps as a reference.
      

       
      

      Regards,
      

      Lluis.
      
			
      

		
			
	      

		
		
	
      
	
      
		
      
			
		
      
	
      
	
      
		
						
						
				
						
				
				
		
		
      
			
		
      
	
      

      

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                on Oct 24, 2025 2:42 AM
            
            
												
						in reply to Lluis
					
										
			            		
        
		
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        Hello,
        

        thanks for your feedback. So basically we will use SER mode only for ADC and never plan to use parallel mode. In this case I think we can directly tie to DGND as stated in datasheet and you confirmed. So, can you confirm that the AD7616 device actively never drives DBx pins in SER mode? I guess in Evalboard you have used 100k pull-down resistors since you provide both options SER and parallel mode.
        

        Regards,
        

        Andreas
        
			
        

		
			
	      

		
		
	
        
	
        
		
        
			
		
        
	
        
	
        
		
						
						
				
						
				
				
		
		
        
			
		
        
	
        

        

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                on Oct 27, 2025 4:57 AM
            
            
												
						in reply to Andy79881
					
										
			            		
          
		
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          Additionally info. We would save 11 resistors per ADC. With an ADC count of 6 these is a total saving of 66 resistors. So, if we can omit those this would be fine due to tight placement needs in our design. In any case safety first: we only omit the series resistors if we are sure that the AD7616 will never drive DBx pins in SER mode.
          
			
          

		
			
	      

		
		
	
          
	
          
		
          
			
		
          
	
          
	
          
		
						
						
				
						
				
				
		
		
          
			
		
          
	
          

          

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          •  Analog Employees  
          
            
						
                            
            
            				
            
                on Nov 11, 2025 3:25 AM
            
            
												
						in reply to Andy79881
					
										
			            		
          
		
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          Hi  ,
          

                   In the AD7616, there are pins that have dual function in parallel or in serial modes. There are pins that are used as Data pins in parallel mode, these pins must be connected to DGND. There is also a pin that is used as Data in parallel mode and Dout pin in serial mode like DB11/SDOB. SDOB pin can be in float or unconnected when it is unused. 
          

          Regards,
          

          Jonathan
          
			
          

		
			
	      

		
		
	
          
	
          
		
          
			
		
          
	
          
	
          
		
						
						
				
						
				
				
		
		
          
			
		
          
	
          

          

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