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ADG5209F Recommended for New Designs
The ADG5208F and ADG5209F are 8:1 and dual 4:1 analog multiplexers. The ADG5208F switches one of eight inputs to a common output, and the ADG5209F switches...
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ADG5209F on Analog.com

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ESD Protection on Sx inputs

		
	
				

			

									
					    phct38
					
							

            
            			
				
									
											
			
			
				
			
			
			    	
			                    
                
				                on Sep 2, 2025 
				
			
			
		

		
		                    	    

        	    
Thread Summary

                The user is experiencing a residual current (10's of mA) through the serial resistance of a differential filter during a surge injection test (IEC61000-4-5) with an ADG5209F multiplexer. The final answer suggests reviewing AN-1436 for surge protection guidance, noting that the ADG5209F shares a similar architecture with the ADG5412F. The user confirmed that the switch is closed and the current likely flows through the common mode capacitors, requiring a 1k serial resistor to handle the surge without a TVS diode.
                        	    

                
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Product Number:  ADG5209F  

    		        		    		    

		    		    
		    			

			    
Hello, my design uses a ADG5209F as a front-end multiplexer with one channel connecting to an external differential input signal. EMC and differential filters are located up-front to the ADG5209F device. 


Upon a surge injection test (IEC61000-4-5), I have a residual current (10's of mA) going through the serial resistance of the front-end differential filter (serial resistors connnect to S1A/S1B pins).


So, I am wondering how this current flows given the characteristics of the ADG5209F device. I have noticed in the device datasheet, page 25, figure 49 an ESD protection functional block connected to the device ground ( I assume it is GND). But I cannot relate the absolue maximum ratings to this ESD protection. 


What would be the voltage threshold of the ESD device and the maximum peak/continuous current ?


Thanks


Best regards


Pascal

			

			
									
		                             
                        

    

                                            
                 Dual-Supply Analog Switches and Multiplexers
                
                                                    
                 Datasheet/Specs
                
                                                    
                 Analog Switches Multiplexers
                
                                                    
                 ADG5209F
                
                                
            

    
    
		


				
				        
        		

			
						
									
												
			
			
                        
                                    
                        
                        
                        
            
			            
						
						
			
			
			
			
		


        
        
        
    
					

			





















	

	

					



			


				
	









	
    
	

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    •  Analog Employees  
    
            
						
                            
            
            				
            
                on Sep 2, 2025 8:47 PM
            
            
						
			            		
    
		
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    Hi  .
    

    

    Hang tight,  will jump in and reply to this thread shortly. 
    

    

    Best,
    

    Gelo
    
			
    

		
			
	      

		
		
	
    
	
    
		
    
			
		
    
	
    
	
    
		
						
						
				
						
				
				
		
		
    
			
		
    
	
    

    

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    •  Analog Employees  
    
            
						
                            
            
            				
            
                on Sep 3, 2025 4:53 AM
            
            
						
			            		
    
		
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    Hi Pascal,
    

    Have you seen the following article describing Surge protection for the ADG5412F, It might be useful in your case.
    

    AN-1436 (Rev. 0)
    

    

    The ADG5208F is of the same architecture as the ADG5412F, The only thing to note is that the On resistance of the ADG5208F is higher so likely a higher resistor would be required in series, but it sounds like you already have that in place.
    

    

    Do you know if the switch is closed when your 10mA residual is flowing?
    

    

    Regards,
    

    David
    
			
    

		
			
	      

		
		
	
    
	
    
		
    
			
		
    
	
    
	
    
		
						
				
						
						
				
				
		
		
    
			
		
    
	
    

    

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                on Sep 3, 2025 6:32 AM
            
            
												
						in reply to Davidforde
					
										
			            		
    
		
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    Hello David,
    

    Yes I am familiar with the AN, An-1380 and the paper you wrote in Analog Dialogue !
    

    I have proceed with new measurements and was able to see that the voltage at the Sx input stays within the power supply values. So yes the switch is closed. 
    

    The filter also has common mode capacitors, and given these new measurements, I am pretty sure that "my current" is actually going through the CM cap.
    

    So I was mislead by the early measurements, thinking that the switch was open (input voltage exceeding power supply rails) and the ESD protection structure was the path for the current. This is likely not the case.
    

    For what is worth, I had to increase the serial resistor to about 1k to handle the surge residual (no TVS).
    

    Thanks for having a look at my case
    

    Best regards 
    

    Pascal
    
			
    

		
			
	      

		
		
	
    
	
    
		
    
			
		
    
	
    
	
    
		
						
						
				
						
				
				
		
		
    
			
		
    
	
    

    

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