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bq51025 load regulation

user357205584
Intellectual 345 points
Other Parts Discussed in Thread: BQ51025, BQ501210, BQ500215, BQ24105

Hi,

I try output of bq51025  change 7V to 10V.(for 2s charger system.)

So,I can change 10V.

When I set the load to 0.45A ,waveform is unstable(Attachment picture).

Why is this such a waveform has appeared ?

Is this something that can be improved ?

(at bq51025EVM schematic,add a capacitor,this volume is 0.1uF) 

best regard!




								


				
				

				
			

		

			
						
									
                			    			                        
						
						
			
			
						
			                        
			
			
				
			  
			

			     
			

		


				    			

						
















	

	

					
    
	
    





		
	
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                          TI__Genius
                        14890 points
                      
    
                          
                   		
		
    
					
    Hello,
    

    What changes did you make to your solution when you changed the output voltage to 10V?  What changes were made to the schematic and did you change the coil?
    

    If you changed the VO_REG resistor values, did you also changet the VIREG resistor values?
    

    Regards,
    

    Dick
    
			
    

		
		
		
		
	
    
	
    
		
    
			
		
    
	
    

	            
                 	
	
    
				
		                
                
                
                
                
                
                
        		
		
				
    
			
		
    
		
		 
		
		
     
    
	
    

    
			
    
			
    
		
    

		
    
	
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						in reply to Dick Stacey
					
									
    
	
    
	                                    
                      
    
                        
                          Intellectual
                        345 points
                      
    
                          
                   		
		
    
					
    Hi,Dick.
    

    
Thank you for your reply.
    

    
I changed only R10 and R12.(at bq51025 EVM schematic)
    
This resistor values is 6.8k.
    
I didn't change the Rx coil.
    

    
Regards.
    

    
Okaz
    
			
    

		
		
		
		
	
    
	
    
		
    
			
		
    
	
    

	            
                	
	
    
				
		                
                
                
                
                
                
                
        		
		
				
    
			
		
    
		
		 
		
		
     
    
	
    

    
			
    
			
    
		
    

		
    
	
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						in reply to user357205584
					
									
    
	
    
	                                    
                      
    
                        
                          TI__Genius
                        14890 points
                      
    
                          
                   		
		
    
					
    Okaz,
    

    What transmitter are you using?  There are some transmitter solutions that will not be able to produce 10V at the output of the RX.  
    

    Additionally, can you measure power transfer frequency (AC1)?  This could help determine if the solution is operating at it's maximum power level.
    

    Regards,
    

    Dick
    
			
    

		
		
		
		
	
    
	
    
		
    
			
		
    
	
    

	            
                 	
	
    
				
		                
                
                
                
                
                
                
        		
		
				
    
			
		
    
		
		 
		
		
     
    
	
    

    
			
    
			
    
		
    

		
    
	
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						in reply to Dick Stacey
					
									
    
	
    
	                                    
                      
    
                        
                          Intellectual
                        345 points
                      
    
                          
                   		
		
    
					
    Hi,Dick
    

    I 'm using the transmitter of Anker manufactured (model A2511).
    

    Frequency is 110-120kHz,please look at the attached figure.
    

    Alignment has shifted a little from the center(about 2mm) .
    

    Thank you for your help.
    

     
    

     
    

    
			
    

		
		
		
		
	
    
	
    
		
    
			
		
    
	
    

	            
                	
	
    
				
		                
                
                
                
                
                
                
        		
		
				
    
			
		
    
		
		 
		
		
     
    
	
    

    
			
    
			
    
		
    

		
    
	
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                          TI__Genius
                        14890 points
                      
    
                          
                   		
		
    
					
    Okaz,
    

    110kHz is the lowest frequency for the power transfer - and the highest power.  It seems that the system is bumping up against it's limit. 
    

    I expect this is due to the 10V output.  See if you can take the output down to 9V and get better results.  I understand this may not be the solution you are looking for, but it may lead us in the right direction for a final solution.
    

    The bq500215 transmitter has been tested extensively with the bq51025 at 10V.  In fact, together, these can deliver up to 10W.  The newly released Qi v1.2 bq501210 can also get 10V from the bq51025.
    

    Both the bq500215 and bq501210 run with a fixed frequency (130kHz) and use the rail voltage to control the power transfer.
    

    Regards,
    

    Dick
    
			
    

		
		
		
		
	
    
	
    
		
    
			
		
    
	
    

	            
                 	
	
    
				
		                
                
                
                
                
                
                
        		
		
				
    
			
		
    
		
		 
		
		
     
    
	
    

    
			
    
			
    
		
    

		
    
	
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						in reply to Dick Stacey
					
									
    
	
    
	                                    
                      
    
                        
                          Intellectual
                        345 points
                      
    
                          
                   		
		
    
					
    Hi,Dick
    

    
I tried to change the output to 9.35V.
    
Variation in the output voltage was smaller .
    
However , to ensure proper operation of the bq24105 ,I want to set the Vout to more than 9.5V.
    
I have changed the C1, C4 , but did not improve .
    
If there is no other approach that can I try ?
    

    
And question
    
Do I use the commercially available of 10W-Charger,bq51025 can be HighPower(10W) operable ?
    

    
Regards
    
			
    

		
		
		
		
	
    
	
    
		
    
			
		
    
	
    

	            
                	
	
    
				
		                
                
                
                
                
                
                
        		
		
				
    
			
		
    
		
		 
		
		
     
    
	
    

    
			
    
			
    
		
    

		
    
	
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