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AD8555 Not Recommended for New Designs
The AD8555 is a zero-drift, sensor signal amplifier with digitally programmable gain and output offset. Designed to easily and accurately convert variable...
Datasheet
AD8555 on Analog.com

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AD8555 Read mode not working

		
	
				

			

									
					    Blackgar
					
							

            
            			
				
									
											
			
			
				
    
			
			
			    	
			                    
                
				                on Dec 2, 2018 
				
			
			
		
    
		
		                     
				
        		
    
		    
		    		    
		    			
    
			    
    Hello,
    

    

    I am checking a new design with AD8555. I have not connect the Strain Gauge sensor yet but i want to verify chip is working. I am trying to go into Read mode and check that chip replies back.
    

    

    I am sending the 1000 0000 0001 11 00 10 0000 0000 0111 1111 1110 code to read the second stage gain but there's no output on the DIGOUT pin.
    

      

    • Bit '1' =  85 usec
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    • Bit '1' =  6 usec
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    • Time between pulses = 22 usec
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    As you can see in the picture, the DIGOUT pin stays low. Is there something i misunderstand?
    

    

      
    
			
    
			
									
		                             
                        

    
    
                                            
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      •  Analog Employees  
      
            
						
                            
            
            				
            
                on Dec 2, 2018 7:20 PM
            
            
						
			            		
      
		
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      Hi,
      

      I'll contact the product owner of this part to address your concern.
      

      Thanks.
      
			
      

		
			
	      

		
		
	
      
	
      
		
      
			
		
      
	
      
	
      
		
						
						
				
						
				
				
		
		
      
			
		
      
	
      

      

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      •  Analog Employees  
      
            
						
                            
            
            				
            
                on Dec 19, 2018 6:19 AM
            
            
						
			            		
      
		
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      Hi,
      

      Have you programmed the AD8555 prior to entering the read mode?
      

      According to the datasheet, in Read Mode the output of the FILT /DIGOUT pin corresponds to the polysilicon fuses programmed prior to entering Read Mode. If you try to read before programming, it is possible that due to the fuses' default value nothing gets shifted out on the FILT/DIGOUT pin, maybe this is what you are seeing. This is the way I interpret it, I will double check with the designer and update you if there is a change of scheme that I'm not aware of.
      

      Thanks,
      

      Sarah
      
			
      

		
			
	      

		
		
	
      
	
      
		
      
			
		
      
	
      
	
      
		
						
						
				
						
				
				
		
		
      
			
		
      
	
      

      

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