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LTC1981 Production
The LTC1981/LTC1982 are low-power, self-contained N-channel MOSFET drivers. An internal voltage tripler allows gates to be driven without the use of any...
Datasheet
LTC1981 on Analog.com

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Will LTC1981 drive two in series MOSFETs?

		
	
				

			

									
					    afmenhem
					
							

            
            			
				
									
											
			
			
				
			
			
			    	
			                    
                
				                on Feb 19, 2018 
				
			
			
		

		
		                     
				
        		

		    
		    		    
		    			

			    
I am design an smart LiPo power pack for an existing device. I need  to switch on/off a LiPo cell (3.7V) from its charger and power path controller used in the existing device.

 
For tjat I'm intending to use a LTC1981 in the following configuration.

 

 
A bidirectional switch is necessary because the PMIC in the existing device will charge the battery when +5V is present and connect the battery to the power rail when +5V is not present.

 
The current will be no more than 1 A and the LTC1981 will be controlled by a tiny micro-controller powered by the battery itself.

 
Do you think that LTC1981 will be able to control the two MOSFETs providing a bidirectional on/off switch?

 
Best regards

			

			
									
		                             
                        

    

                                            
                 High-Side Switches and MOSFET Drivers
                
                                                    
                 battery cell bidirectional switch
                
                                                    
                 Power Monitor  Control  and Protection
                
                                                    
                 LTC1981
                
                                
            

    
    
		


				
				        
        		

			
						
									
												
			
			
                        
                                    
                        
                                                    
                        
            
			            
						
						
			
			
			
			
		


        
        
        
    
					

			





















	

	

					



			


				
	









	
    
	

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    •  Analog Employees  
    
            
						
                            
            
            				
            
                on Feb 22, 2018 6:11 PM
            
            
						
			            		
    
		
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    afmenhem
    
 
    What company do you represent and what's annual quantity of this project?
    
 
    The LTC1981 was not designed to drive back-to-back MOSFETs, it is not in datasheet. Generally speaking, though, you can do this, below is LTspice simulation of the discussed circuit. The biggest problem is relatively long turn on/off. Also, we did not tested LTC1981 in this configuration.
    
 
    You might look at LTC4412 with configuration on page 11, Figure 4. You can use related DC1635A to test your circuit on the bench.
    
			
    

		
			
	      

		
		
	
    
	
    
		
    
			
		
    
	
    
	
    
		
						
						
				
				
				
				
		
		
    
			
		
    
	
    

    

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    •  Analog Employees  
    
            
						
                            
            
            				
            
                on Aug 2, 2018 12:02 PM
            
            
						
			            		
    
		
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    This question has been assumed as answered either offline via email or with a multi-part answer. This question has now been closed out. If you have an inquiry related to this topic please post a new question in the applicable product forum.

    Thank you,
    EZ Admin
    
			
    

		
			
	      

		
		
	
    
	
    
		
    
			
		
    
	
    
	
    
		
						
				
						
				
				
				
		
		
    
			
		
    
	
    

    

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