• State Resolved
  • Locked Locked
  • Replies 4 replies
  • Subscribers 63 subscribers
  • Views 188 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TPS54202HEVM-716: Suspicious efficiency of EVM Test

Kian Lin
Expert 4000 points
Part Number: TPS54202HEVM-716

Hi,

I tested efficiency of TPS54202HEVM and found some suspicious efficiency. Below is the test data, and suspicious efficiency marked yellow. The test condition is Vin=6/12/18/24V, Vo=5V, Io=0.5/1/1.5/2A.

I have tried to find what's the problem. So I tested the SW node voltage, the cause of high efficiency when Vin=24V, Io=0.5A is that converter enter eco-mode and lose some  drive signal, see below picture. But in datasheet Iskip=300mA, so can you tell me why converter enter eco-mode in this condition.

Finally, about the suspicious efficiency when Vin=6V and load current is large, I don't know what's the problem. The SW node voltage is normal.

  • 0
    TI__Expert 8100 points

    Hi Kian,

    Could you please share your setup for different test? And could you please detailed clarify your suspicion about marked efficiency?

    BRs

    Zixu

  • 0 in reply to Zixu Wang
    TI__Expert 4000 points

    Hi Zixu,

    Below picture is my setup:

    In order to rule out the accuracy problem of the indication of the DC source, I also tested efficiency with multimeter. About suspicious efficiency, I think the efficiency when Vin=6V and heavy load should be higher than other input voltage. But in the test result, it's lower than other efficiency. I also tested the SW node voltage and didn't find any problem. 

    BRs

    Kian

    
			
    

		
		
		
		
	
    
	
    
		
    
			
		
    
	
    

	            
                 	
	
    
				
		                
                
                
                
                
                
                
        		
		
				
    
			
		
    
		
		 
		
		
     
    
	
    

    
			
    
			
    
		
    

		
    
	
    • 

		
	
  • 
		
    
			 


	
			
		
	









    
	
    
		
    
							
					
    
		
    
			
													+1
							
			
				
									
							
						
				
			
			
			
												
						in reply to Kian Lin
					
									
    
	
    
	                                    
                      
    
                        
                          TI__Expert
                        8100 points
                      
    
                          
                   		
		
    
					
    Hi Kian,
    

    For measuring efficiency, please measure voltage across C2 as input voltage since the input terminal is far away from IC and it exists voltage drop in PCB trace, which could cause inaccurate results. The following figure could be referred for measuring efficiency.
    

     
    

    For efficiency under 6Vin,5Vout at 2A loading, it is quite low from my result as well. The root cause lies on the minimum off time. Since the loading is heavy, it triggers minimum off time. And for the long on-time period, high side FET is on, whose Rds(on) contributes to more conduction power loss. The switching frequency does not change much under all conditions, meaning that switching loss are almost the same. So the efficiency of 6Vin,5Vout at 2A loading is quite lower.
    

    For other marked weird conditions, the root cause possibly lies on the method of measurement.
    

    BRs
    

    Zixu  
    
			
    

		
		
		
		
	
    
	
    
		
    
			
		
    
	
    

	            
                 	
	
    
				
		                
                
                
                
                
                
                
        		
		
				
    
			
		
    
		
		 
		
		
     
    
	
    

    
			
    
			
    
		
    

		
    
	
    • 

		
	
  • 
		
    
			 


	
		
	
	









    
	
    
		
    
							
					
    
		
    
			
													0
							
			
				
									
							
						
				
			
			
			
												
						in reply to Zixu Wang
					
									
    
	
    
	                                    
                      
    
                        
                          TI__Expert
                        4000 points
                      
    
                          
                   		
		
    
					
    Hi Zixu,
    

    Thanks~
    
			
    

		
		
		
		
	
    
	
    
		
    
			
		
    
	
    

	            
                 	
	
    
				
		                
                
                
                
                
                
                
        		
		
				
    
			
		
    
		
		 
		
		
     
    
	
    

    
			
    
			
    
		
    

		
    
	
    •