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LTC3310 not coming up



		

			

									
					    kepco
					
							

			
				
									
											
			
			
				
    
			
			
			    	
			                    
                
				                on Mar 9, 2022 
				
			
			
		
    

				
		
    
		    		    
		    
		    	
			
    Hi,
    

    We have following circuit converting 5V to 3.3V using LTC3310. But the output were are getting is 0.027V. We have isolated all the output side from load with same results. Any idea what we are missing here? Could not find anything wrong with the circuit. The EN pin is high and LED D18 is ON.
    

    

     
    
									
			        
		
    

				
						
        

		
    
			
						
									
									
						
						
			
			
			
			
		
    

        
        

					
    
			
    


    
















    
	
    
	
    
					



			








	
	
	
	



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							FormerMember
					
      
		
      
			
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									FormerMember
							        
			
			
			
    
            
						
                            
            
            				
            
                on Mar 9, 2022 10:09 PM
            
            
					
    
	
    

		
		
    
					
    Hi Kepco,
    

    What I'm seeing in your circuit is that your NAND gate inputs are left floating and this might be a problem. Can you check if the circuit works by removing the NAND logic gate and pulling the EN pin high?
    

    Regards,
    

    Jhun
    
			
    

		
			
	      

		
		
	
    
	
    
		
    
			
		
    
	
    
	
    
		
						
						
						
						
				
				
		
		
    
			
		
    
	
    

    


	

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                on Mar 10, 2022 8:24 PM
            
            
												
						in reply to FormerMember
					
									
      
	
      

		
		
      
					
      Thanks Jhun. Totally missed it. The schematic I was first checking showed this resistor installed and EN was showing high when measured. After installing the resistor now the regulator is working but it is putting out 3.1V for some reason. It is driving few ICs on the load side. Under no load it gives 3.3V output.
      
			
      

		
			
	      

		
		
	
      
	
      
		
      
			
		
      
	
      
	
      
		
						
						
				
						
				
				
		
		
      
			
		
      
	
      

      

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							FormerMember
					
      
		
      
			
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									FormerMember
							        
			
			
			
            
						
                            
            
            				
            
                on Mar 10, 2022 8:38 PM
            
            
												
						in reply to kepco
					
									
      
	
      

		
		
      
					
      Hi Kepco,
      

      How much load is the regulator sourcing? Also, I would like to suggest that the PGOOD LED source be the input voltage instead of getting it from the output. This is to ensure that only the ICs are the load for the regulator.
      

      You can also try using a different resistor values with a tighter tolerance of 0.1% for both the top and bottom resistors.
      

      Edit: Please also consider this snippet below. It's on page 15.
      

       
      

      Regards,
      

      Jhun
      
			
      

		
			
	      

		
		
	
      
	
      
		
      
			
		
      
	
      
	
      
		
						
						
				
						
				
				
		
		
      
			
		
      
	
      

      

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							FormerMember
					
        
		
        
			
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									FormerMember
							        
			
			
			
      
            
						
                            
            
            				
            
                on Mar 10, 2022 8:38 PM
            
            
												
						in reply to kepco
					
									
      
	
      

		
		
      
					
      Hi Kepco,
      

      How much load is the regulator sourcing? Also, I would like to suggest that the PGOOD LED source be the input voltage instead of getting it from the output. This is to ensure that only the ICs are the load for the regulator.
      

      You can also try using a different resistor values with a tighter tolerance of 0.1% for both the top and bottom resistors.
      

      Edit: Please also consider this snippet below. It's on page 15.
      

       
      

      Regards,
      

      Jhun
      
			
      

		
			
	      

		
		
	
      
	
      
		
      
			
		
      
	
      
	
      
		
						
						
				
						
				
				
		
		
      
			
		
      
	
      

      





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