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ADG1234 Production
The ADG1233 and ADG1234 are monolithic iCMOS® analog switches comprising three independently selectable single-pole, double throw SPDT switches and four...
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ADG1234 on Analog.com

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ADG1234 analog inputs clamping diodes



		

			

									
					    VictorCanoz
					
							

			
				
									
											
			
			
				
    
			
			
			    	
			                    
                
				                on Mar 26, 2018 
				
			
			
		
    

				
		
    
		    		    
		    
		    	
			
    Hi,
    We plan to use the ADG1234 in one of our products. It will be powered with +/-15V rails (see picture attached). We would like to protect it against over voltages up to +/-25V. There is a 220R series resistor with each analog input we want to protect. We can't increase the resistor value to keep enough BW.

    So my questions are :

    
 
      
  
    1. Are there clamping diode to VSS in the ADG1234?
      2. 
  
    2. In order to handle the max current in over voltage condition (around 50mA), could you please suggest protection diodes (connected between input/output terminals and VDD, VSS) with very low capacitance (let's say 1pF total max.) which can meet the ADG1234 specs & our 25V input protection requirement?

      3. 
 
    
 
    Thank you in advance,
    
									
			        
		
    

							
    
				
				
			
    
					
						
        

    
    Tags: 
                                            
                 Dual-Supply Analog Switches and Multiplexers
                
                                                    
                 adg1234
                
                                                    
                 Analog Switches Multiplexers
                
                                                    
                 switches and multiplexers
                
                                
            
    
    
    

		
    
			
						
									
									
						
						
			
			
			
			
		
    

        
        

					
    
			
    


    
















    
	
    
	
    
					



			


				
	









	
      
	

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      •  Analog Employees  
      
            
						
                            
            
            				
            
                on Mar 28, 2018 2:40 PM
            
            
					
      
	
      

		
		
      
					
      Hi,
      
 
      It sounds like one of our over-voltage protection switches may be a better fit for your application. Have a look at the ADG5243F. This is a triple SPDT Switch that has over-voltage protection on the source side of up to +/-55 V.  Once the input to the switch exceeds the supply voltage by 0.7 V the switch goes high impedance blocking the fault from the down stream circuitry. This would eliminate the requirement for your resistor and any diodes on the input.
      
 
      Let me know if this would be a fit for your application
      
 
      Regards,
      
 
      David
      
			
      

		
			
	      

		
		
	
      
	
      
		
      
			
		
      
	
      
	
      
		
						
						
				
						
				
				
		
		
      
			
		
      
	
      

      

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                on Apr 3, 2018 4:11 PM
            
            
					
        
	
        

		
		
        
					
        Hi David,
        
 
        At first flance, the ADG5243F looked good for our application.
        
 
        Unfortunately, we needed to use the switch in a SPDT configuration (with
        
 
        the high voltage on the SP side), so this IC does not fit.
        
 
        In the end we have completely changed the architecture.
        
 
        Anyway thanks for your help,
        
 
        Victor
        
			
        

		
			
	      

		
		
	
        
	
        
		
        
			
		
        
	
        
	
        
		
						
						
				
						
				
				
		
		
        
			
		
        
	
        

        

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                on Aug 2, 2018 12:03 PM
            
            
					
          
	
          

		
		
          
					
          This question has been assumed as answered either offline via email or with a multi-part answer. This question has now been closed out. If you have an inquiry related to this topic please post a new question in the applicable product forum.

          Thank you,
          EZ Admin
          
			
          

		
			
	      

		
		
	
          
	
          
		
          
			
		
          
	
          
	
          
		
						
				
						
						
				
				
		
		
          
			
		
          
	
          

          

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