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AD8479 Recommended for New Designs
The AD8479 is a difference amplifier with a very high input common-mode voltage range. The AD8479 is a precision device that allows the user to accurately...
Datasheet
AD8479 on Analog.com

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Current sense amplifier for phase current and high common mode voltage 400V - Single Supply non isolated



		

			

									
					    ChaitanyaB
					
							

			
				
									
											
			
			
				
    
			
			
			    	
			                    
                
				                on Apr 14, 2021 
				
			
			
		
    

				
		
    
		    		    
		    
		    	
			
    Hi,
    

    

    I am looking for a current sense amplifier for the phase current sensing application for a 3 phase PMSM motor. I have shunt in each motor phase, my DC link voltage can be 400V. I could not find high common mode voltage amplifier with single supply.  I want to use non-isolated solution. I found AD8479 but it is dual supply. My current is AC so bi directional, I need to be able lift the ref pin to the half of my ADC voltage (SAR Single Ended). Will that work for AD8479 in single supply configuration? is there any other chip that can do in single supply configuration? 
    

    

    Thanks
    
									
			        
		
    

				
						
        

    
    Tags: 
                                            
                 amplifiers
                
                                                    
                 ad8479
                
                                                    
                 Specialty Amplifiers
                
                                                    
                 Difference Amplifiers
                
                                
            
    
    
    

		
    
			
						
									
									
						
						
			
			
			
			
		
    

        
        

					
    
			
    


    
















    
	
    
	
    
					



			


				
	









	
      
	

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      •  Analog Employees  
      •  Super User  
      
            
						
                            
            
            				
            
                on May 10, 2021 10:06 PM
            
            
					
      
	
      

		
		
      
					
      Hi ChaitanyaB,

      I apologize for the late reply.

      AD8479 can actually operate with a single-supply. You can view the details on page 13 of the datasheet.
      The major difference of single-supply operation with the dual-supply operation is that the input common-mode voltage range is reduced.
      The input common-mode voltage can be calculated as follows:

      VCM(±) = 61 × (VX or VY(±)) − (60 × VREF)

      From calculation, I think we can get above +/-400V input common-mode voltage range by using at least 8V reference voltage and 16V supply voltage. Please let us know if it works with your ADC.

      For other chips that can do single-supply configuration, I will check and get back to you.

      Best Regards,
      Sham
      
			
      

		
			
	      

		
		
	
      
	
      
		
      
			
		
      
	
      
	
      
		
						
						
				
						
				
				
		
		
      
			
		
      
	
      

      

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      •  Analog Employees  
      •  Super User  
      
            
						
                            
            
            				
            
                on May 11, 2021 12:36 AM
            
            
					
      
	
      

		
		
      
					
      Hi again ChaitanyaB,

      For now, only AD8479 can accommodate +/- 400V on single-supply. 
      Other chips can only accommodate less than  +/-300V (single-supply also).

      Best Regards,
      Sham  
      
			
      

		
			
	      

		
		
	
      
	
      
		
      
			
		
      
	
      
	
      
		
						
						
				
						
				
				
		
		
      
			
		
      
	
      

      

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