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LT3065 Recommended for New Designs
The LT3065 Series are micropower, low noise, low dropout voltage (LDO) linear regulators that operate over a 1.6V to 45V input voltage range. The devices...
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LT3065 on Analog.com

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LT3065 current source: max SHDN switching freqeuncy

		
	
				

			

									
					    Topspin
					
							

            
            			
				
									
											
			
			
				
    
			
			
			    	
			                    
                
				                on Sep 18, 2024 
				
			
			
		
    
		
		                     
				
        		
    
		    
		    		    
    
		      		            		        
    Category: Hardware
    
    		        		            		    
    Product Number:  LT3065  
    
    		        		    		    
    
		    		    
		    			
    
			    
    Hi,
    

    

    I would like to use the LT3065 as a current source for a led and I am basically replicating this circuit
    

     
    

    I removed the Cref capacitor to decrease the transient time
    

     
    

    

    However I am finding a too low turnoff time ( yellow pin SHDN and blu is ADJ pin)
    

     
    

    

    What is the max switching frequency of SHDN? I need to go up to 10KHz
    

    Do you know why this is happening?
    
			
    
			
									
		                             
                        

    
    
                                            
                 hardware
                
                                                    
                 LDO Linear Regulators
                
                                                    
                 LT3065
                
                                                    
                 Positive Linear Regulators (LDO)
                
                                
            
    
    
    
		
    

				
				        
        		
    
			
						
									
												
			
			
                        
                                    
                        
                                                    
                        
            
			            
						
						
			
			
			
			
		
    

        
        
        
    
					
    
			
    


    
















    
	
    
	
    
					



			


				
	









	
      
	

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      •  Analog Employees  
      
            
						
                            
            
            				
            
                on Sep 18, 2024 12:57 PM
            
            
						
			            		
      
		
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      Hi.  I am worried the LT3065 won't be able to turn on fast enough for a 10kHz on-off rate.  Plus, you noticed the LED current decays slowly, probably as the 10uF discharges through the 6 Ohm and the LED.  Below in the image I show in LTspice a way that the LT3092 current source can easily turn on and off at 10kHz.  There are other reference designs in the LT3092 datasheet that are similar current sources.  Can you consider the LT3092?  I attached my LTspice file.  
      

      sim ckt and result_1.pngLT3092_1.asc
      

      

      

      
			
      

		
			
	      

		
		
	
      
	
      
		
      
			
		
      
	
      
	
      
		
						
						
				
				
				
				
		
		
      
			
		
      
	
      

      

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