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The ADV7403 is a high quality, single chip, multiformat video decoder and graphics digitizer. This multiformat decoder supports the conversion of PAL,...
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ADV7403 on Analog.com

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ADV7403 I2C Series 100 ohm Resistor



		

			

									
					    Sagar_BN
					
							

			
				
									
											
			
			
				
    
			
			
			    	
			                    
                
				                on Feb 21, 2023 
				
			
			
		
    

				
		
    
		    		    
		    
		    		            		        
    Category: Hardware
    
    		        		            		    
    Product Number:  ADV7403BSTZ-110 
    
    		        		    		    	
			
    Hello All,
    

    We are using ADV7403 in our design. I have design query related to I2C interface connections made in ADV7403 Eval Board Schematic.
    

    100 ohms Series Resistor is used SDA and SCL lines of I2C. Please let us know the importance of usage of this resistor. Is 100 ohm Resistor Eval Board Requirement to interface with external board ?
    

    We were planning to have 4K7 Pullup resistor on I2C lines(open drain) to connect with our FPGA. Please let us know.
    
								
    

				
				
		
    
			
						
									
									
						
						
			
			
			
			
		
    

        
        

					
    
			
    


    


	















    
	
    
	
    
					



			


				
	









	
      
	

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      •  Analog Employees  
      •  Super User  
      
            
			                            
                        
                on Feb 21, 2023 11:02 PM
            
            
					
      
	
      

		
		
      
					
      A 100 Ohm series resistor is not needed.  Normally I'll drop a 10-22 Ohm resistor in that position although you can easily get rid of it.  The series resistor has 3 benefits in my opinion.
      

      1) Provides an easy way to disconnect the chip from the I2C bus by removing it in case there's address collisions or other problems.
      

      2) Provides ESD protection to the I2C pins on the part.  If the bus never goes off board then there is no ESD issues to worrry about.
      

      3) Provides an easy probe point to monitor the I2C bus activity.
      
			
      

		
		
		
		
	
      
	
      
		
      
			
		
      
	
      
	
      
		
						
				
						
						
				
				
		
		
      
			
		
      
	
      

      

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