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ADM3485E Production
The ADM3485E is a 3.3 V, low power data transceiver with ±15 kV ESD protection, suitable for half-duplex communication on multipoint bus transmission lines...
Datasheet
ADM3485E on Analog.com

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TVS USING FOR ADM3485E

		
	
				

			

									
					    Emirhankose
					
							

            
            			
				
									
											
			
			
				
    
			
			
			    	
			                    
                
				                on Jun 30, 2025 
				
			
			
		
    
		
		                    	    
    
        	    
    Thread Summary
    
                The user is concerned about the high clamp voltage of the SM712-02HTG TVS diode when used with the ADM3485E RS485 transceiver. The final answer recommends using ultra-low clamping voltage TVS diodes or adding extra protection circuitry like a surge-rated resistor, TBU, or GDT. ADI also suggests modern RS485 transceivers with high common-mode voltage and high ESD protection.
                        	    
    
                
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    Category: Hardware
    
    		        		            		    
    Product Number:  ADM3485EARZ-REEL7, ADM3485E 
    
    		        		    		    
    
		    		    
		    			
    
			    
    I’m using the SM712-02HTG TVS diode in my RS485 designs. Although the datasheet application section indicates it’s for RS485, the clamp voltage seems a bit too high to me. Because of this, I’m hesitant to use it with the ADM3485E. What approach would you recommend in this situation?
    
			
    
			
									
		                             
                        

    
    
                                            
                 hardware
                
                                                    
                 RS-232 / RS-422 / RS-485 / RS-562
                
                                                    
                 ADM3485EARZ-REEL7
                
                                                    
                 RS-485 and RS-422
                
                                                    
                 adm3485e
                
                                
            
    
    
    
		
    

				
				        
        		
    
			
						
									
												
			
			
                        
                                    
                        
                        
                        
            
			            
						
						
			
			
			
			
		
    

        
        
        
    
					
    
			
    


    
















    
	
    
	
    
					



			


				
	









	
      
	

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      •  Analog Employees  
      
            
						
                            
            
            				
            
                on Jun 30, 2025 10:21 PM
            
            
						
			            		
      
		
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      Hi,
      

      You are correct. The max. clamping voltage of SM712 exceeds the Abs. Max. of the ADM3485. Since the ADM3485 does not include an ESD spec, the simplest ESD protection circuity is using a bidirectional TVS diode on I/O lines. For TVS diodes with a stand-off/ work voltage greater than 12V, the max. clamping voltage is typically greater than 20V, however ultra-low clamping voltage TVS diodes are available. Extra protection circuitry, such as series with a surge-rated resistor, adding TBU or GDT on the I/O line, will help to achieve more robust surge requirements. The level of protection depends on your application’s requirement.
      

      In addition, ADI provides modern RS485 transceivers with high common-mode voltage and high ESD protection.
      

      Best,
      

      Jane
      
			
      

		
			
	      

		
		
	
      
	
      
		
      
			
		
      
	
      
	
      
		
						
				
						
						
				
				
		
		
      
			
		
      
	
      

      

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