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LT8602 Recommended for New Designs
The LT8602 is a quad channel, current mode, monolithic buck switching regulator with a programmable power-on reset. All regulators are synchronized to...
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LT8602 on Analog.com

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LT8602 Iq higher than expected.



		

			

									
					    WarreS
					
							

			
				
									
											
			
			
				
    
			
			
			    	
			                    
                
				                on Sep 13, 2018 
				
			
			
		
    

				
		
    
		    		    
		    
		    	
			
    Hi,
    

    I have the following circuit using the LT8602 for power distribution and rudimentary SLA charging.   In the configuration below, I am seeing 2mA quiescent. current  with only the PVin2 source attached, (no PVin1 has no source)
    

    PVin1 is the input for the optional battery charging sources, the output is set to 7.7V.  Vin and PVin2 is supplied by a 6V sealed lead-acid battery.
    

    The circuit works as intended and the rails come up as expected.  The problem is the quiescent current though.  I am expecting to see something in the range of microamps.   Is there anything obviously wrong with the design that would cause the Iq to be so high?
    

    Thanks.
    

    

     
    
								
    

				
				
		
    
			
						
									
									
						
						
			
			
			
			
		
    

        
        

					
    
			
    


    


	
    
		
	
    















    
	
    
	
    
					



			


				
	









	
      
	

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      •  Analog Employees  
      
            
			                            
                        
                on Sep 15, 2018 1:54 AM
            
            
					
      
	
      

		
		
      
					
      Hi Warres,
      

      Make sure the circuit runs in burst mode. When it is in burst mode, the IQ changes versus EN/UVLO as shown in Fig 8 of the datasheet. 
      

      Check the datasheet of the D1000 and see how much leakage current it has.  
      
			
      

		
		
		
		
	
      
	
      
		
      
			
		
      
	
      
	
      
		
						
				
				
						
				
				
		
		
      
			
		
      
	
      

      

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                on Sep 18, 2018 1:51 AM
            
            
												
						in reply to ADIApproved
					
									
        
	
        

		
		
        
					
        Hi,
        

        I removed D1000 from the board, and it had no affect.
        

        I have confirmed that I am running in Burst Mode, and I have removed some other circuitry downstream of that and the current was approximately 1mA when a source was connected to PVin2.  If I tie both PVin1 and PVin2 together, the current draw is 50uA, which is more acceptable, however for this circuit that won't work.  I need PVin1 and PVin2 to come from different power supplies, and PVin1 is from a solar panel that won't always have a high enough voltage to get a regulated output from Output 1.
        
			
        

		
		
		
		
	
        
	
        
		
        
			
		
        
	
        
	
        
		
						
				
				
						
				
				
		
		
        
			
		
        
	
        

        

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        •  Analog Employees  
        
            
			                            
                        
                on Sep 27, 2018 9:04 PM
            
            
					
        
	
        

		
		
        
					
        Please show the switching node waveform for both channel 1 and channel 2. The TRKSS1 and TRKSS2 should not be tied together. 
        
			
        

		
		
		
		
	
        
	
        
		
        
			
		
        
	
        
	
        
		
						
				
				
						
				
				
		
		
        
			
		
        
	
        

        

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