Products In This Thread

LTC2942 Production
The LTC2942 measures battery charge state, battery voltage and chip temperature in handheld PC and portable product applications. Its operating range is...
Datasheet
LTC2942 on Analog.com

  • Replies 3 replies
  • Subscribers 38 subscribers
  • Views 1637 views
  • Users 0 members are here
Options
Related 

        

            Post
             Go back to editing
        

    

    


    

    




















	
	
			
	
		
		
	
	
		

		
Problem with LTC2942



		

			

									
					    GTG_I+D
					
							

			
				
									
											
			
			
				
    
			
			
			    	
			                    
                
				                on Dec 3, 2018 
				
			
			
		
    

				
		
    
		    		    
		    
		    	
			
    Good afternoon everyone from Spain,
    

    I'm Juan Domingo, from GTG Ingenieros.
    

    We have used the LTC2942 in the design of an electronic card for a portable device. We have connected this IC as indicated in the datasheet. Schematic in pdf file is attached.
    

    This device is powered from a 1-cell Li-Ion battery. It is a removable cylindrical battery; therefore, it is possible that, when removing the battery, the polarity of the battery can be inverted when it is inserted next.
    

    We have verified that, by reversing the polarity of the battery, the LTC2942 burned and stopped working altogether.
    

    I make the following queries:
    

    1) .- Does the LTC2942 have some type of polarity inversion protection?.
    

    2) .- Could you explain to me what caused this problem?.
    

    3) .- Given that it is possible that a polarity reversal of the battery occurs, could you tell me if this is appropriate battery monitor or recommend another better reference?
    

    While waiting to receive your answers, I appreciate your cooperation.
    Sincerely,
    JuanD
    

    

    PMIC SCHEMATIC.pdf
    
								
    

				
				
		
    
			
						
									
									
						
						
			
			
			
			
		
    

        
        

					
    
			
    


    


	
    
		
	
    















    
	
    
	
    
					



			








	
	
	
	



Parents
	
      
	

    • 
	
      






      
	
      
		
      
							
					
      
		
      
			
											
			
				
									
							        
			
			
			
      •  Analog Employees  
      
            
			                            
                        
                on Dec 4, 2018 11:25 AM
            
            
					
      
	
      

		
		
      
					
      1) LTC2942 does not have reverse polarity protection.
      

      2) LTC2942 has internal ESD protection diodes, e.g. from GND (anode) to SENSE+. Applying reverse polarity will cause a big forward current through this diode and damage the part.
      

      3) You need some reverse polarity protection device e.g. LTC4365
      

      https://www.analog.com/en/products/ltc4365.html#product-overview
      

      Or you built your own discrete with a single PMOS, just search for "pmos reverse polarity protection", there are tons of examples available.
      
			
      

		
		
		
		
	
      
	
      
		
      
			
		
      
	
      
	
      
		
						
				
				
						
				
				
		
		
      
			
		
      
	
      

      

      • 

	

    • 
	
      






      
	
      
		
      
							
					
      
		
      
			
											
			
				
									
							        
			
			
			
        
            
			                            
                        
                on Dec 4, 2018 10:33 PM
            
            
												
						in reply to patrick-w.
					
									
        
	
        

		
		
        
					
        Hi Patrick,
        


        Thank you very much for answering. Your recommendation is smart, but I think it will not be appropriate in our case. Next, I provide more information about our work scenario:
        

        1) .- The battery we use is connected to a battery charging IC from Analog Devices (LTC3555). If we use a reverse polarity protection device (LTC4365, or similar), this device will not allow current circulation for charging the battery.
        

        2) .- In the different tests carried out, we have verified that, on some occasion, the LTC2942 is also damaged when inserting and extracting the battery with the correct polarity.
        

        3) .- The LTC2942 is used to measure the battery voltage and communicate via I2C with a microcontroller.
        

        Any ideas for solving this problem?.
        

        Is it more appropriate
        

        Will be better to use an IC battery monitor with high-side or low-side current sensing?
        

        Thanks in advance,
        

        JuanD
        
			
        

		
		
		
		
	
        
	
        
		
        
			
		
        
	
        
	
        
		
						
				
				
						
				
				
		
		
        
			
		
        
	
        

        

        • 

	
      



Reply

        


      • 
	
        






        
	
        
		
        
							
					
        
		
        
			
											
			
				
									
							        
			
			
			
          
            
			                            
                        
                on Dec 4, 2018 10:33 PM
            
            
												
						in reply to patrick-w.
					
									
          
	
          

		
		
          
					
          Hi Patrick,
          


          Thank you very much for answering. Your recommendation is smart, but I think it will not be appropriate in our case. Next, I provide more information about our work scenario:
          

          1) .- The battery we use is connected to a battery charging IC from Analog Devices (LTC3555). If we use a reverse polarity protection device (LTC4365, or similar), this device will not allow current circulation for charging the battery.
          

          2) .- In the different tests carried out, we have verified that, on some occasion, the LTC2942 is also damaged when inserting and extracting the battery with the correct polarity.
          

          3) .- The LTC2942 is used to measure the battery voltage and communicate via I2C with a microcontroller.
          

          Any ideas for solving this problem?.
          

          Is it more appropriate
          

          Will be better to use an IC battery monitor with high-side or low-side current sensing?
          

          Thanks in advance,
          

          JuanD
          
			
          

		
		
		
		
	
          
	
          
		
          
			
		
          
	
          
	
          
		
						
				
				
						
				
				
		
		
          
			
		
          
	
          

          

          • 


        


Children