Products Mentioned

MAX485E Production
The MAX481E, MAX483E, MAX485E, MAX487E- MAX491E, and MAX1487E are low-power transceivers for RS-485 and RS-422 communications in harsh environments. Each...
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MAX485E on Analog.com

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MAX485E glitch when around zero -crossing

		
	
				

			

									
					    SEKOO
					
							

            
            			
				
									
											
			
			
				
    
			
			
			    	
			                    
                
				                on Nov 19, 2024 
				
			
			
		
    
		
		                     
				
        		
    
		    
		    		    
		    			
    
			    
    Hello
    

    I experience that the MAX385E is causing glitches as seen in the attached image around time: 321,0 that exceed the +-200mV threshold levels. It is in this case used to transmit a clock signal, so it is a bit problematic to have false edges.
    

    Is the chip defect or is there another explanation?
    

    

     
    
			
    
			
									    
    
			        
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[edited by: SEKOO at 12:07 AM (GMT -5) on 20 Nov 2024]
				
    
						
		                                 
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                 MAX485
                
                                                    
                 RS-232 / RS-422 / RS-485 / RS-562
                
                                                    
                 max385E
                
                                                    
                 RS-485 and RS-422
                
                                
            
    
    
    
		
    

				
				        
        		
    
			
						
									
												
			
			
                        
                                    
                        
                        
                        
            
			            
						
						
			
			
			
			
		
    

        
        
        
    
					
    
			
    


    
















    
	
    
	
    
					



			


				
	









	
      
	

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      •  Analog Employees  
      
            
						
                            
            
            				
            
                on Nov 19, 2024 11:58 PM
            
            
						
			            		
      
		
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      Hello Sekdo - are you able to share basic schematic, along with how system is configured so I can give you a more detailed answer. Is the scope shot of the A or B line with the MAX485 driving the bus? The MAX485 is a very popular part, and it looks like quite a low data rate (300ms pulse).  What is driving the DI pin and are you monitoring the input and the VCC supply to make sure these are stable?. How is the bus terminated?. 
      
			
      

		
			
	      

		
		
	
      
	
      
		
      
			
		
      
	
      
	
      
		
						
						
				
						
				
				
		
		
      
			
		
      
	
      

      

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                on Nov 20, 2024 4:18 AM
            
            
												
						in reply to ADIApproved
					
										
			            		
        
		
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        Hello Seanl
        

        The data (green) is sent over a RS485 line as well as the clock (yellow) is sent over a separate RS485 line. The clock rate is 50kHz and the pulse width is 2.5 microseconds. I will provide more detail as soon as possible. 
        

         
        
			
        

		
			
	      

		
		
	
        
	
        
		
        
			
		
        
	
        
	
        
		
						
						
				
						
				
				
		
		
        
			
		
        
	
        

        

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