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LTC4120 Recommended for New Designs
The LTC4120 is a constant-current/constant-voltage wireless receiver and battery charger. An external programming resistor sets the charge current up to...
Datasheet
LTC4120 on Analog.com

LTC4125 Recommended for New Designs
The LTC4125 is a simple and high performance monolithic full bridge resonant driver capable of delivering over 5W of power wirelessly to a properly tuned...
Datasheet
LTC4125 on Analog.com

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LTC4120 Wireless Power Receiver Constant Voltage mode



		

			

									
					    DvdOne
					
							

			
				
									
											
			
			
				
    
			
			
			    	
			                    
                
				                on Jul 12, 2021 
				
			
			
		
    

				
		
    
		    		    
		    
		    	
			
    Hi! 
    

    I'm developing a wireless powered system WITHOUT battery. Therefore, I need a constant voltage (and not constant current) node at the LTC4120 wireless power receiver output. I'm using the evaluation board, which features the LTC4125 as transmitter IC and the LTC4120 as receiver IC. Up to now, I got only constant-voltage/constant-current, and I was wondering if there's any way to convert this kind of supply in the constant-voltage one I need. I don't know if there's any pin I should tune inside the LTC4120 (I couldn't find anything like that in the datasheet) or if I have to add an external circuit. So, can you suggest me a solution? Is there any external circuit or different receiver IC I should use? Thanks!
    
								
    

				
				
		
    
			
						
									
									
						
						
			
			
			
			
		
    

        
        

					
    
			
    


    


	















    
	
    
	
    
					



			








	
	
	
	



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      •  Analog Employees  
      
            
			                            
                        
                on Aug 6, 2021 7:32 PM
            
            
					
      
	
      

		
		
      
					
      Hi DvdOne, 
      

      Unfortunately LTC4120 does not support this constant voltage solution. The only way to get a semi-constant voltage is to use a really large cap on BAT pin to replace the battery. The LTC4124 has a VCC pin that is voltage regulated. You can connect a 10uF on BAT on LTC4124 and you will observe around 5V on LTC4124 VCC. How much current do you need for your solution ? What is your load range on your receiver side ? Will there be any fast transient on the load side ? 
      

      Thanks,
      

      Wenwei. 
      
			
      

		
		
		
		
	
      
	
      
		
      
			
		
      
	
      
	
      
		
						
				
						
						
				
				
		
		
      
			
		
      
	
      

      

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													0
							
			
				
									
							        
			
			
			
        
            
			                            
                        
                on Aug 12, 2021 6:30 PM
            
            
												
						in reply to Wenwei
					
									
        
	
        

		
		
        
					
        Hi Wenwei,
        

        Thanks for your answer.
        

        I would need 200mA, more or less, as output current at 5V. I tried using a full bridge rectifier instead of the LTC receiver module, and the circuit is behaving well. Do you think this could be a good solution? Or it would be better to use the LTC4124 as you suggested? (There won't be any fast transient on the load side)
        

        P.S: I’m transmitting with the LTC4125.
        

         
        

        Thank you and have a great day,
        

        Davide
        
			
        

		
		
		
		
	
        
	
        
		
        
			
		
        
	
        
	
        
		
						
						
				
						
				
				
		
		
        
			
		
        
	
        

        

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													0
							
			
				
									
							        
			
			
			
          
            
			                            
                        
                on Aug 12, 2021 6:30 PM
            
            
												
						in reply to Wenwei
					
									
          
	
          

		
		
          
					
          Hi Wenwei,
          

          Thanks for your answer.
          

          I would need 200mA, more or less, as output current at 5V. I tried using a full bridge rectifier instead of the LTC receiver module, and the circuit is behaving well. Do you think this could be a good solution? Or it would be better to use the LTC4124 as you suggested? (There won't be any fast transient on the load side)
          

          P.S: I’m transmitting with the LTC4125.
          

           
          

          Thank you and have a great day,
          

          Davide
          
			
          

		
		
		
		
	
          
	
          
		
          
			
		
          
	
          
	
          
		
						
						
				
						
				
				
		
		
          
			
		
          
	
          

          

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