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ADG1606 Production
The ADG1606 and ADG1607 are monolithic iCMOS® analog multiplexers comprising of 16 single channels and eight differential channels, respectively. The ADG1606...
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ADG1606 on Analog.com

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Problem with ADG1606 protection



		

			

									
					    imanjohn
					
							

			
				
									
											
			
			
				
    
			
			
			    	
			                    
                
				                on Feb 26, 2013 
				
			
			
		
    

				
		
    
		    		    
		    
		    	
			
    Hello,
    
 
    We use an ADG1606 MUX as the final stage of our circuit to connect to external units (Hot unplug condition is normal in our application). From datasheet, I understood that "Overvoltages at IN, S, or D are clamped by internal diodes. Current should be limited to the maximum ratings given" and from engineerzone I know that ADG1606 is protected against ESD. 
    
 
    We have implemented following items as protection for the MUX (Our switch is powered from a single supply):
    
 
    1- A blocking 1N4148 diode is placed in series with supply to VDD pin. (The circuit is not subjected to negative voltages and we eliminated blocking diode in GND side.)
    
 
    2- A current limiter circuit is implemented in D channel and prevents currents above 60mA to pass S channels to D channel (S->D). (D ->S is under control and over-current is not possible.)
    
 
    Before we implement protection methods above, we had different kinds of failures, but recently we had only one type of failure (It is rare, but it happens); A single channel is shortened to GND. It seems an INTERNAL Zener diode of channel is burnt out and the result is short-circuit to GND. If the MUX is protected against over-voltage, why does it happen? What is the solution? 
    
 
    Look forward to your reply,
    
 
    Best regards 
    
									
			        
		
    

				
				
		
    
			
						
									
									
						
						
			
			
			
			
		
    

        
        

					
    
			
    


    


	
    
		
	
    















    
	
    
	
    
					



			


				
	









	
      
	

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      •  Analog Employees  
      
            
			                            
                        
                on Feb 26, 2013 10:29 AM
            
            
					
      
	
      

		
		
      
					
      Hi imanjohn,
      
 
      Have you any more details on what the fault is that is damaging the part? Is it a positive or negative over voltage condition?
      
 
      I have attached a tutorial which outlines protection methods to be used. You have implemented one of them but you should note that it is important to verify that the protection method used is acceptable for all possible errors the part can be subjected to.
      
 
      The ADG1606 data sheet states that the ADG1606 analog inputs have a max rating of 30mA in an over voltage condition (Vdd+0.3V) and so the 60 mA limit you mentioned below is too high for this case.
      
 
      If you have any further questions, let me know.
      
 
      Regards,
      
 
      Joe
      
			
      

		
			
	      

		
				SwitchandMultiplexerDesignConsiderationsforHostileenviroments.pdf
			
	
      
	
      
		
      
			
		
      
	
      
	
      
		
						
						
						
						
				
				
		
		
      
			
		
      
	
      

      

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                on Feb 27, 2013 7:48 PM
            
            
					
        
	
        

		
		
        
					
        Hello Joe,
        
 
        Thank you very much for comments and the document. I think this should solve the problem. But, believe me, the datasheet was not clear and I remember when I first read that part, I thought it must be a mistake of datasheet. Now that you clarified its intention, I guess we have two choices to implement:
        
 
        1- Clamp any over-voltage using Schottky or Germanium (is Germanium diode alright?) diodes and leave the current-limiter circuit adjusted for 60mA 
        
 
        2- Limit the current, passing through S channels, to max 30mA and let the over-voltage conditions happen (I prefer this solution)
        
 
        By the way, over-voltages are only positive and almost in 50% of cases, it is normal to have over-voltages in our application. 
        
 
        Look forward to have your comments on the solutions above or please let me know any other solution you may recommend.
        
 
        Best Regards,
        
 
        imanjohn
        
			
        

		
			
	      

		
		
	
        
	
        
		
        
			
		
        
	
        
	
        
		
						
						
				
						
				
				
		
		
        
			
		
        
	
        

        

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        •  Analog Employees  
        
            
			                            
                        
                on Feb 28, 2013 11:19 AM
            
            
					
        
	
        

		
		
        
					
        HI imanjohn,
        
 
        If you prefer the second option you must also ensure that the voltage on the pin does not exceed the voltage max ratings. It may be best to use the current limiter with a Schottky diode to ensure both over current and over voltage requirements are met.
        
 
        ADI also do a range of over voltage suppression parts (the ADG465 and ADG476) which may be of use in the application, as they will ensure that signal is within defined rails. I have attached the data sheets for your consideration.
        
 
        Regards,
        
 
        Joe
        
			
        

		
			
	      

		
				attachments.zip
			
	
        
	
        
		
        
			
		
        
	
        
	
        
		
						
				
						
						
				
				
		
		
        
			
		
        
	
        

        

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