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ADM7150 Recommended for New Designs
The ADM7150 is a low dropout linear regulator that operates from 4.5 V to 16 V and provides up to 800 mA of output current. Using an advanced proprietary...
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ADM7150 on Analog.com

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ADM7150 increase output voltage

		
	
				

			

									
					    dave111
					
							

            
            			
				
									
											
			
			
				
			
			
			    	
			                    
                
				                on Jan 21, 2015 
				
			
			
		

		
		                     
				
        		

		    
		    		    
		    			

			    
Is it possible to increase the ADM7150 output voltage to 12V using this kind of circuit?

 
will the output noise increased?

 
what is the max and min value of r1 and r2 can be used?

 

			

			
									
		                             
                        

    

                                            
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							FormerMember
					
    
		
    
		    
		    		    
			
				
									FormerMember
							        
			
			
			
            
						
                            
            
            				
            
                on Jan 21, 2015 7:22 PM
            
            
						
			            		
    
		
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    If you really need low noise (<2uVrms or even <20uVrms) then the LM317 will not be able to achieve that.
    
 
    Most LM317 have noise levels of 50-100 times per volt or 1000x the noise if you are trying to generate 12V.
    
 
    Could you use the ADP7118 or ADP7142? This will have noise around 12uV at 12V output.
    
 
    See the DESIGN EXAMPLE OF USING THE NOISE REDUCTION NETWORK WITH THE ADP7142 
    
 
    in the following app note:
    
 
    http://www.analog.com/static/imported-files/application_notes/AN-1329.pdf
    
 
    ADI's new LDOs have this ability to use fixed voltage LDOs, like a 5V preset version, and raise it's voltage above the set point instead of having to use the 1.2V version of the LDO to do that. Noise is improved by setting the reference voltage internally in addition to the noise reduction technique described in the app note.
    
 
    Luca
    
			
    

		
			
	      

		
		
	
    
	
    
		
    
			
		
    
	
    
	
    
		
						
						
				
				
				
				
		
		
    
			
		
    
	
    

    

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							FormerMember
					
    
		
    
		    
		    		    
			
				
									FormerMember
							        
			
			
			
            
						
                            
            
            				
            
                on Jan 21, 2015 7:54 PM
            
            
						
			            		
    
		
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    Theoretically you could do something like this, but your caps should go to ground.
    
 
    Yes, the noise will increase.  The R1/R2 have to draw the min load current required by
    
 
    the regulator, which is zero for the 7150.  If they are too low, all the current goes into
    
 
    the divider and you have nothing left for your load.
    
 
    Best to use an LM317 three terminal adjustable that was designed for this.
    
 
    Also see the three app notes.
    
 
    Harry
    
 

     
    
			
    

		
			
	      

		
		
	
    
	
    
		
    
			
		
    
	
    
	
    
		
						
						
				
				
				
				
		
		
    
			
		
    
	
    

    

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    •  Analog Employees  
    
            
						
                            
            
            				
            
                on Aug 2, 2018 10:53 AM
            
            
						
			            		
    
		
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    This question has been assumed as answered either offline via email or with a multi-part answer. This question has now been closed out. If you have an inquiry related to this topic please post a new question in the applicable product forum.

    Thank you,
    EZ Admin
    
			
    

		
			
	      

		
		
	
    
	
    
		
    
			
		
    
	
    
	
    
		
						
				
						
				
				
				
		
		
    
			
		
    
	
    

    

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