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Rs-170 Buffer for long cable



		

			

									
					    baralelca
					
							

			
				
									
											
			
			
				
    
			
			
			    	
			                    
                
				                on May 4, 2016 
				
			
			
		
    

				
		
    
		    		    
		    
		    	
			
    Hi,
    
 
    We're designing with the ADV7123 Video DAC to implement  RS-170 video signal,
    
 
    the video signal should drive more then a 10 Meters cable and according to the Datasheet it's recommended to use buffers such as the AD848,
    
 
    Do we need to connect the buffer to a dual supply voltage (negative and positive) to support the RS-170 signal?
    
 
    Can you recommend on such application?
    
 
    Thanks in advance,
    
 
    Barak
    
								
    

				
				
		
    
			
						
									
									
						
						
			
			
			
			
		
    

        
        

					
    
			
    


    


	
    
		
	
    















    
	
    
	
    
					



			


				
	









	
      
	

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      •  Analog Employees  
      
            
			                            
                        
                on May 30, 2016 7:06 AM
            
            
					
      
	
      

		
		
      
					
      Hi, Barak.
      
 
      Apologies for the very late reply.
      
 
      The AD848 was rated to work with a minimum supply of +/-4.5V so if you want a single supply, +9V is the minimum supply you need. Figure 27 of the ADV7123 shows the configuration of AD848 as an output buffer. Please take note that as you use +9V, your output will only be limited to 2V (rload=150ohms) so even though you have a gain of 2, your output will still be 2V. To have a higher output voltage, better use a dual supply for the buffer.  
      
 
      Figure 26 of the ADV7123 shows the connections of ADV7123 using a Gray scale (also called the RS-170) video format as input.
      
 
      Regards,
      
 
      Anna
      
			
      

		
		
		
		
	
      
	
      
		
      
			
		
      
	
      
	
      
		
						
				
						
						
				
				
		
		
      
			
		
      
	
      

      

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