Products Mentioned

MAX485 Production
The MAX481, MAX483, MAX485, MAX487–MAX491, and MAX1487 are low-power transceivers for RS-485 and RS-422 communication. Each part contains one driver...
Datasheet
MAX485 on Analog.com

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...
Datasheet
MAX485E on Analog.com

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MAX485ESA+T Data Flow issue

		
	
				

			

									
					    Avaneesh
					
							

            
            			
				
									
											
			
			
				
    
			
			
			    	
			                    
                
				                on Apr 17, 2024 
				
			
			
		
    
		
		                     
				
        		
    
		    
		    		    
    
		      		            		        
    Category: Hardware
    
    		        		            		    
    Product Number:  MAX485ESA+T, MAX485E 
    
    		        		    		    
    
		    		    
		    			
    
			    
    Hi  Team,
    

    We are using MAX485ESA+T in one of our application, 
    

    MCU VCC is 3V3 (MCU VCC can be upto 5V but we are operating MCU at 3V3 only)  and MAX485ESA+T VCC is 5V
    

    So we are getting the data but dataflow is not in continuous manner i.e. it send the data and stops for few Milliseconds and then start showing data and again stops for few milli seconds
    

    Can you please suggest why this is happening and how I can resolve this issue.
    

    
			
    
			
									
		                             
                        

    
    
                                            
                 hardware
                
                                                    
                 DATAFLOW
                
                                                    
                 MAX485
                
                                                    
                 RS-232 / RS-422 / RS-485 / RS-562
                
                                                    
                 MAX485E
                
                                        
                                            
                
                
                                        
                                            
                
                
                                        
                                            
                
                
                                
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      •  Analog Employees  
      
            
						
                            
            
            				
            
                on Apr 17, 2024 1:02 PM
            
            
						
			            		
      
		
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      Hello Avaneesh -
      

      I assume your MCU is sending data at less than 2.5Mbps which is the max. data rate for the MAX485 and that the output enable pins (/RE and DE) are driven to the correct logic levels to enable the receiver output (RO) or Driver Output. Also please confirm the IO switching levels  (Voh/Vol and Vih/Vil) for your MCU.  For MAX485 for RO pin Voh = 3.5V (min) and Vol = 0.4V (max). For DI, DE, and /RE pins the Vih = 2.0V(min) and Vil = 0.8V (max). I think you need to see if you can use a 5V IO on your MCU to correctly meet the MAX485 levels.
      
			
      

		
			
	      

		
		
	
      
	
      
		
      
			
		
      
	
      
	
      
		
						
						
				
						
				
				
		
		
      
			
		
      
	
      

      

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