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The output voltage of LTC3822-1 is low

		            
		

			

									
					    Jack_167
					
							


			
				
									
											
			
			
				
			
			
			    	
			                    
                
				                on Feb 5, 2020 
				
			
			
		

		
     
				
		

		    		    
		    
		    	
			
LTC38221 buck chip was used.3.3v to 1.8v, but the output is not up to 1.6v, I use the circuit on the datasheet, as shown in the figure below: two-layer single-side amplifier.The load is connected to an approximate no-load resistance of 3K.


The voltage is Vin 3.7v Vout 1.6v Vfb 0.3v.


I removed the two feedback resistors and tested the Vfb. The voltage was only 0.25v, less than 0.6v.


See below pic.


The oscilloscope measured the up and down MOS driver waveforms as follows,


     

									
			        
		


				
						
        

    
Tags: 
                                            
                 dcdc_converter
                
                                                    
                 LTC3822
                
                                                    
                 buck converter
                
                                
            

    
    

		

			
						
									
												
			
			
                        
                                    
                        
                        
                        
            
			            
						
						
			
			
			
			
		


        
        

					

			





















	

	

					



			


				
	









	
    
	

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    •  Analog Employees  
    
            
						
                            
            
            				
            
                on Mar 23, 2020 10:14 PM
            
                                    
					
    
	
    

		
		
    
					
    Surprising problems usually come because of the PCB layout especially if you have not tried the circuit on a proto board. I recommend that you get hold of the available demo board DC1105A since it matches with your input and output requirement and compare board characteristics from there. You may also compare waveforms with LTspice.
    
			
    

		
			
	      

		
		
	
    
	
    
		
    
			
		
    
	
    
	
    
		
						
						
						
						
				
				
		
		
    
			
		
    
	
    

    

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