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ADM1270 Recommended for New Designs
The ADM1270 is a current-limiting controller that provides inrush current limiting and overcurrent protection for modular or battery-powered systems. When...
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ADM1270 on Analog.com

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ADM1270 Issue



		

			

									
					    alex.chen
					
							

			
				
									
											
			
			
				
    
			
			
			    	
			                    
                
				                on Nov 19, 2014 
				
			
			
		
    

				
		
    
		    		    
		    
		    	
			
    hi sir
    
 
    I  want to design the ADM1270 in my system, but I have two issue need to clarity before layout
    
 
    Q1.ADM1270 use the PMOS to be the switch, but PMOS cost Which expensive than NMOS, Why ADI use PMOS?
    
 
    Q2.ADM1270 Have reverse protect by RPFG,But I can't find the RPFG vary which no matter passive voltage or negative voltage input
    
 
         can you help to clarity?
    
 
    thanks
    
								
    

				
				
		
    
			
						
									
									
						
						
			
			
			
			
		
    

        
        

					
    
			
    


    


	















    
	
    
	
    
					



			


				
	









	
      
	

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      •  Analog Employees  
      
            
			                            
                        
                on Nov 21, 2014 12:46 AM
            
            
					
      
	
      

		
		
      
					
      Alex,
      
 
      the ADM1270 uses a PFET because it is easier to drive the gate. A device controlling an NFET would have to generate a floating gate drive circuitry to be able to turn on the NFET. This means the voltage on the gate would be >70V for a 60V application.
      
 
      RFPG is used to protect against reverse current through the sense resistor and not reverse voltage on the IC. The voltage on RFPG is 12V below Vcc when there is positive current flow, if the device detects negative current flow then the RFPG voltage goes to Vcc.
      
 
      Attached is a preliminary design tool you could use to start your design.
      
 
      Best Regards, LucaV
      
			
      

		
		
		
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