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ADG508A Production
The ADG508A and ADG509A are CMOS monolithic analog multiplexers with eight channels and dual four channels, respectively. The ADG508A switches one of...
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ADG508A on Analog.com

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What is the effect on ADG508A about a floating input?

		
	
				

			

									
					    sguirand
					
							

            
            			
				
									
											
			
			
				
    
			
			
			    	
			                    
                
				                on Jan 16, 2018 
				
			
			
		
    
		
		                    	    
    
        	    
    Thread Summary
    
                The user is experiencing glitches when reading ADC data from an AD7880CR connected to ADG508AKR multiplexers, particularly around a floating input. The final answer recommends avoiding floating inputs by grounding unused pins to prevent charge buildup and discharge issues.
                        	    
    
                
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    Hi,
    
 
    I'm working with two ADG508AKR connected to an ADC (AD7880CR) through an OP297GS.
    
 
    On one of the multiplexer, I have an input which is an option to my design. When this option is not installed, the input is floating.
    
 
    We are reading each channels (except the floating one) in a loop. In this loop, we are selecting the channel, then proceeding to the ADC conversion, then reading the ADC Data.
    
 
    We observed some glitch when reading the ADC data around the floating input.
    
 
    Is a floating input can cause an issue on the MUX selection?
    
 
    Is there any recommendation about unused input? 
    
 
    Thanks,
    
 
    Sabine G.
    
			
    
			
									
		                             
                        

    
    
                                            
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