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LT3012 Recommended for New Designs
The LT3012 is a high voltage, micropower low dropout linear regulator. The device is capable of supplying 250mA of output current with a dropout voltage...
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LT3012 on Analog.com

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2 pc of LT3012 paralleled together (but no need for load sharing)



		

			

									
					    Dirk_67
					
							

			
				
									
											
			
			
				
    
			
			
			    	
			                    
                
				                on Apr 2, 2021 
				
			
			
		
    

				
		
    
		    		    
		    
		    	
			
    I have an application, that consist of 2 boards:
     - "MCU-Board" (powered by USB or by the "Base-Board")
     - "Base-Board" (powered by 12V or by the "MCU-Bord")

    In normal operation this boards are plugged together, and powered by 12V (automotive).

    my Idea was to use two LT3012 and make use of the built-in "reverse current protection" of this part.
    -> boesche-electronics.de/.../LT3012.png

    # When the boards are sparated, both boards have to run on its own.

    # Can I plug the boards together (3,3V/GND) without using any additional diode or switching logic ? (by using the built in "reverse current protection" of the LT3012)

    # When plugged together both(!) boards have to run from the "5V-USB" only OR from the "12V-automotive" only OR even both(!) of this supplies connected.

    # there is no need for load-sharing

    Is it "allowed"/possible to simply connect the two outputs of the two LT3012 together in the described way ?
    
									
			        
		
    

				
						
        

    
    Tags: 
                                            
                 LDO Linear Regulators
                
                                                    
                 Positive Linear Regulators (LDO)
                
                                                    
                 lt3012
                
                                
            
    
    
    

		
    
			
						
									
									
						
						
			
			
			
			
		
    

        
        

					
    
			
    


    


	















    
	
    
	
    
					



			


				
	









	
      
	

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      •  Analog Employees  
      
            
			                            
                                                                                                                        
            
				
			
            
					
      
	
      

		
		
      
					
      I usually don't recommend paralleling LT3012s directly for stability reasons.
      

      Can you use the approach using the LT3042 that I show in the image below?
      

      

      LT3042 DS parallel_2.png
      

      

      
			
      

		
			
	      

		
		
	
      
	
      
		
      
			
		
      
	
      
	
      
		
						
						
				
						
				
				
		
		
      
			
		
      
	
      

      

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						in reply to ARad
					
									
        
	
        

		
		
        
					
        >>"Can you use the approach using the LT3042 that I show in the image below?"
        unfortunately I need the wide input voltage range of the LT3012 (4...80V)

        If I understand you right the stability Problem does occur only at the time when both LDO's are powered ?

         looking again on my picture: https://boesche-electronics.de/tmp/LT3012.png  ...
        

        would it do the trick / enhance the stability 
        if I trim e.g. the 12V LDO to 3.4V and the other (5V/USB-) LDO to 3.2V
        and then
        when both LDO's are powered only the 12V LDO [3.4V] delivers current ?
        (cause the other (5V/USB-) LDO [3.2V] can not act as a sink because of its reverse current protection ?)
        
			
        

		
			
	      

		
		
	
        
	
        
		
        
			
		
        
	
        
	
        
		
						
						
				
						
				
				
		
		
        
			
		
        
	
        

        

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