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ADM238L Production
The ADM2xx family of line drivers/receivers is intended for all EIA-232-E and V.28 communications interfaces, especially in applications where ±12 V is...
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ADM238L on Analog.com

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ADM238L pin-matching alternative



		

			

									
					    mcp
					
							

			
				
									
											
			
			
				
    
			
			
			    	
			                    
                
				                on Apr 25, 2013 
				
			
			
		
    

				
		
    
		    		    
		    
		    	
			
    Hello,
    
 
    We have been using the ADM238LJRZ in a "mature" product line with thousands of systems operating in the field. In some cases, the negative charge pump has been found to be damaged when cable lengths between devices are longer than approx 50 feet, which appears to have created conditions where wire capacitances exceed maximum allowable values. A detailed Failure Analysis confirmed that an EOS "event" had damaged the charge pump causing abnormally low output voltage. We are looking at implementing a TVS/Zener solution to mitigate this susceptibility but wonder if there might be a pin-to-pin alternative available that is inherently more robust than the ADM238L? As a side question, is there an established test method for this type of issue? One that could recreate the EOS damage and then be used to know that a TVS solution is working?
    
 
    Best regards,
    
 
    Mark
    
									
			        
		
    

				
						
        

    
    Tags: 
                                            
                 RS-232 and RS-562
                
                                                    
                 RS-232 / RS-422 / RS-485 / RS-562
                
                                                    
                 eos
                
                                                    
                 adm238l
                
                                                    
                 tvs
                
                                
            
    
    
    

		
    
			
						
									
									
						
						
			
			
			
			
		
    

        
        

					
    
			
    


    
















    
	
    
	
    
					



			








	
	
	
	



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      •  Analog Employees  
      
            
						
                            
            
            				
            
                on Apr 26, 2013 6:08 PM
            
            
					
      
	
      

		
		
      
					
      Hi Mark, 
      
 
      The ADM208EARZ may be an option. This is a pin compatible device with ESD hardened RS-232 pins up to 15kV.
      
 
      I'm not that familiar with test methods for ESD type issues. The only way I can think over verifying this is to zap the RS-232 pins with an ESD gun to try to replicate the issue on the ADM238L. Then try the same test with the ESD hardened ADM208E device to verify the issue is resolved. 
      
 
      I'd expect to see some data errors if the cable length and capacitance gets too large. Worth keeping an eye on this and using low capacitance cables if you have to use very long cables.
      
 
      Rgds,
      
 
      Paul
      
			
      

		
			
	      

		
		
	
      
	
      
		
      
			
		
      
	
      
	
      
		
						
						
				
						
				
				
		
		
      
			
		
      
	
      

      

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      •  Analog Employees  
      
            
						
                            
            
            				
            
                on Apr 26, 2013 6:08 PM
            
            
					
      
	
      

		
		
      
					
      Hi Mark, 
      
 
      The ADM208EARZ may be an option. This is a pin compatible device with ESD hardened RS-232 pins up to 15kV.
      
 
      I'm not that familiar with test methods for ESD type issues. The only way I can think over verifying this is to zap the RS-232 pins with an ESD gun to try to replicate the issue on the ADM238L. Then try the same test with the ESD hardened ADM208E device to verify the issue is resolved. 
      
 
      I'd expect to see some data errors if the cable length and capacitance gets too large. Worth keeping an eye on this and using low capacitance cables if you have to use very long cables.
      
 
      Rgds,
      
 
      Paul
      
			
      

		
			
	      

		
		
	
      
	
      
		
      
			
		
      
	
      
	
      
		
						
						
				
						
				
				
		
		
      
			
		
      
	
      

      

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