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ADXL355 datasheet units



		

			

									
					    HaydenR
					
							

			
				
									
											
			
			
				
    
			
			
			    	
			                    
                
				                on Oct 12, 2022 
				
			
			
		
    

				
		
    
		    		    
		    
		    		            		        
    Category: Datasheet/Specs
    
    		        		            		    
    Product Number:  ADXL355 
    
    		        		        		        
    Software Version: Rev A
    
    		    		    	
			
    Hello,
    

    I have some confusion with the datasheet for the ADXL355 datasheet (https://www.analog.com/media/en/technical-documentation/data-sheets/ADXL354_355.pdf). There are tables for high pass filter settings on pages 24 and 37, but the values given on 24 are 100x lower than the values on 37. Additionally, page 24 shows figure 61, with a cutoff listed at 9.8801[kHz] for 4[kHz] ODR which is incompatible with the 1[kHz] lowpass filter. Based on what I can measure in the lab, it seems like the values in table 10 are correct and the units in figure 61 are mislabeled (should be Hz). Can anyone confirm this, or am I reading something incorrectly?
    

    Thanks,
    

    Hayden
    
								
    

				
				
		
    
			
						
									
									
						
						
			
			
			
			
		
    

        
        

					
    
			
    


    


	















    
	
    
	
    
					



			


				
	









	
      
	

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      •  Analog Employees  
      
            
			                            
                        
                on Oct 12, 2022 6:37 PM
            
            
					
      
	
      

		
		
      
					
      Hi Hayden, 
      

      Maybe I don't understand the problem correctly, but I do not think the datasheet is mistaken in this case.
      

      Figure 62 in the datasheet shows the HPF cutoff frequency is 9.88Hz for 4kHz ORD and HPF_CORNER = b'001. From the equation described Filter register in the 24.7*1e-4*4000 = 9.88Hz.
      

      Regarding to the figure 61, that figure it is a simulation of the decimation filter (digital LPF) response for 4000Hz ODR setting. The text in page 24 also mentions "Note that Figure 61 does not include the fixed frequency analog, low-pass, antialiasing filter with a fixed 3 dB bandwidth of approximately 1.5 kHz." 
      

      I hope this helps, 
      

      Pablo. 
      
			
      

		
		
		
		
	
      
	
      
		
      
			
		
      
	
      
	
      
		
						
				
						
						
				
				
		
		
      
			
		
      
	
      

      

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													0
							
			
				
									
							        
			
			
			
        
            
			                            
                        
                on Oct 12, 2022 6:55 PM
            
            
												
						in reply to PdelCorro
					
									
        
	
        

		
		
        
					
        Thanks for the prompt response. Based on your response I can see we are reading different data sheets. I looked online for a revision and found Rev.B, which is accurate as you described. I trusted the linked datasheet on DigiKey, which goes to Rev.A, and contains the errors I described, so my mistake.
        

        As a side note, the difference between these data sheets is Rev.A is referred to as "ADXL354_355.pdf" (see link in my comment) and Rev.B is referred to as "adxl354_adxl355.pdf" (https://www.analog.com/media/en/technical-documentation/data-sheets/adxl354_adxl355.pdf). This is quite confusing in my opinion, can something be done to redirect from Rev.A to Rev.B or at least make it more clear that a new revision is available in the old document?
        
			
        

		
		
		
		
	
        
	
        
		
        
			
		
        
	
        
	
        
		
						
						
				
						
				
				
		
		
        
			
		
        
	
        

        

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        •  Analog Employees  
        
            
			                            
                        
                on Oct 12, 2022 8:47 PM
            
            
												
						in reply to HaydenR
					
									
        
	
        

		
		
        
					
        Oh ok, I will let our editorial/web team know about your feedback, hopefully they can get this implemented. 
        
			
        

		
		
		
		
	
        
	
        
		
        
			
		
        
	
        
	
        
		
						
						
				
						
				
				
		
		
        
			
		
        
	
        

        

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