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AD7763 Production
The AD7763 high performance, 24-bit, S-? analog-to-digital converter (ADC) combines wide input bandwidth and high speed with the benefits of S-? conversion...
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AD7763 on Analog.com

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AD7763 Filter Download Question

    
		

			

									
					    GaryM
					
							


			
				
									
											
			
			
				
    
			
			
			    	
			                    
                
				                on Jul 18, 2013 
				
			
			
		
    
		
     
				
		
    
		    		    
		    
		    	
			
    Hi,
    
 
     
    
 
    I am having problems downloading filters to the AD7763. I have tried the example in the datasheet (in Table 16) so that I know the checksum is correct but I am not getting the FILTER_OK or DL_OK bits set in the Status read (the other bits of the Status read are fine - and UFILTER is set).
    
 
     
    
 
    I am convinced that I have no problems with the data timing and I have a good clean clock, frame sync and data. I am clocking at 12.8 MHz.
    
 
     
    
 
    I would be grateful for answers to the following questions:
    
 
     
    
 
    1. Are there are any errors or omissions in the datasheet with respect to the download?
    
 
    2. Is there any difference between the effects of applying a hardware SYNC (via the SYNC pin) or writing to the SYNC bit in Control Register 1?
    
 
    3. In Table 16 it is not clear whether the delay for the checksum should be before or after writing the checksum, could you clarify this please?
    
 
     
    
 
    Many thanks,
    
 
     
    
 
    Gary Moore
    
									
			        
		
    

				
						
        

    
    Tags: 
                                            
                 Single Channel A/D Converters
                
                                                    
                 ad7763
                
                                                    
                 Precision A/D Converters
                
                                
            
    
    
    

		
    
			
						
									
									
						
						
			
			
			
			
		
    

        
        

					
    
			
    


    
















    
	
    
	
    
					



			








	
	
	
	



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                on Oct 21, 2013 1:12 PM
            

            
					
        
	
        

		
		
        
					
        Hi Chris,
        
 
        My configuration is as follows:
        
 
        I have 4 AD7763s running together using MCLK = 25.6 MHz and with CDIV = 0 so that ICLK = MCLK/2 = 12.8 MHz.
        
 
        We have the decimation set to x16 so our output sample rate is 100 kHz.
        
 
        In an earlier version of our design we were running with CDIV = 1 and I’m fairly sure that this worked OK, i.e. we could successfully download the filter. Unfortunately it is not straightforward to re-create that arrangement.
        
 
        As I said in my response to Francois, it's possible that my problems are caused by the SYNC pulse width as we discovered that it wasn't as wide as we intended. I have not tried the download since we fixed that but I will let you know if this is successful.
        
 
        Thanks,
        
 
        Gary
        
			
        

		
			
	      

		
		
	
        
	
        
		
        
			
		
        
	
        
	
        
		
						
						
				
						
				
				
		
		
        
			
		
        
	
        

        

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													0
							
			
				
									
							        
			
			
			
          
            
						
                            
            
            				
            
                on Oct 21, 2013 1:12 PM
            

            
					
          
	
          

		
		
          
					
          Hi Chris,
          
 
          My configuration is as follows:
          
 
          I have 4 AD7763s running together using MCLK = 25.6 MHz and with CDIV = 0 so that ICLK = MCLK/2 = 12.8 MHz.
          
 
          We have the decimation set to x16 so our output sample rate is 100 kHz.
          
 
          In an earlier version of our design we were running with CDIV = 1 and I’m fairly sure that this worked OK, i.e. we could successfully download the filter. Unfortunately it is not straightforward to re-create that arrangement.
          
 
          As I said in my response to Francois, it's possible that my problems are caused by the SYNC pulse width as we discovered that it wasn't as wide as we intended. I have not tried the download since we fixed that but I will let you know if this is successful.
          
 
          Thanks,
          
 
          Gary
          
			
          

		
			
	      

		
		
	
          
	
          
		
          
			
		
          
	
          
	
          
		
						
						
				
						
				
				
		
		
          
			
		
          
	
          

          

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