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VDDB pin current of  MAX22025AWA+

		
	
				

			

									
					    S1640
					
							

            
            			
				
									
											
			
			
				
    
			
			
			    	
			                    
                
				                on Jan 6, 2026 
				
			
			
		
    
		
		                    	    
    
        	    
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                The user inquires about the VDDB pin current consumption of the MAX22025AWA+ during communication. The final answer explains that the IDDB current is the sum of the internal current (4.0 to 5.5mA when TxD is low) and the output current, which depends on the load and bus configuration. The transmitter output characteristic plots on page 15 can help estimate the driver's Thevenin resistance for specific load conditions.
                        	    
    
                
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    Hello, 
    

    Thank you for your always our support.
    Regarding VDDB pin current of MAX22025AWA+ during communication, I would like to confirm.
    When there is no communication, in the datasheet that the Supply Current IDDB = 4.0 to 5.5mA on page 7, but how is the current consumption during communication?
    

    Does the MAX22025AWA+ consume approximately 20-30mA ,or more during serial communication (It depends on the load connection situation...)?
    


    Thank you.
    Best regards,
    



     


    
			
    
			
									    
    
			        
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[編集者:S1640、編集時刻: 7 Jan 2026 日 5:25 AM 時 (GMT -5)]
				
    
						
		                             
                        

    
    
                                            
                 Datasheet/Specs
                
                                                    
                 Digital Isolation Technology
                
                                                    
                 receiver
                
                                                    
                 Standard Digital Isolators
                
                                
            
    
    
    
		
    

				
				        
        		
    
			
						
									
												
			
			
                        
                                    
                        
                        
                        
            
			            
						
						
			
			
			
			
		
    

        
        
        
    
					
    
			
    


    
















    
	
    
	
    
					



			


				
	









	
      
	

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      •  Analog Employees  
      
            
						
                            
            
            				
            
                on Jan 15, 2026 2:27 PM
            
            
						
			            		
      
		
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      As you correctly mention, the total current flowing into VDDB, IDDB, depends on the external load conditions.
      

      The IDDB current will be a combination of the current consumed internally by the transceiver which will depend on the state of the transceiver and the output current driving the load which depends on the output driver state and the external load / bus.
      

      The EC table lists the IDDB when TxD is low which is the higher current operational state - this can be inferred from the supply current vs temperature plots on page 14 which show plots with TxD low and high.  The low plots all have slightly higher currents than the high plots and so are a reasonable choice for the part's internal current consumption.
      

      The MAX22025's drivers are only active under specific conditions, see the Function tables on pg 17.  The transmitter output characteristic plots on page 15 can be used to estimate the driver's Thevenin resistance which then can be used in the computation of the output current for the particular load/bus configuration.
      

      The IDDB current is then the sum of the internal current plus the output current into the bus.
      

      Eric
      
			
      

		
			
	      

		
		
	
      
	
      
		
      
			
		
      
	
      
	
      
		
						
						
						
						
				
				
		
		
      
			
		
      
	
      

      

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