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LT3471 to power a dual power supply



		

			

									
						Siddhesh_P
					
							

			
				
									
											
							 		
		        	            							
			
			    	
			                    
                
				                on Aug 20, 2019 
				
			
			
		


				
		

		    		    
		    
		    	
			
Hello,


I am working on an application which needs a dual power supply. The rest of circuitry is ready and while looking for a dual power supply IC, i came across LT3471. My application would need a +25v and -25v supply, with a current requirement of 100mA on each rail. I just want to confirm whether my judgement of this IC regarding the requirement is correct. 


Parallelly, i will be simulating the circuit on LTSpice and check myself for any issues that might come en-route. 


Looking forward to suggestions. 

								


				
				
		

			
						
									
									
						
						
			
			
			
			
		


					

			





	














	

	

					



			


				
	









	
    
	

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                on Aug 20, 2019 12:25 PM
            
            
					
    
	
    

		
		
    
					
    Hi, 
    

    I have tried the simulation om LT Spice. I am getting the desired voltage levels but the time to settle is a bit too much. it is taking more than 25mSec to reach the desired voltage level on both the rails. Also the optional diode on negative voltage rail as shown in ev board schematic doesn't seem to work. 
    

    Is there any way the settling time can be reduced? I have attached a snip of schematic and simulation result. Looking forward to suggestions. 
    

      
    
			
    

		
		
		
		
	
    
	
    
		
    
			
		
    
	
    
	
    
		
						
						
				
						
				
				
		
		
    
			
		
    
	
    

    

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                                 Analog Employees 
                                
                            
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                on Aug 20, 2019 2:30 PM
            
            
					
    
	
    

		
		
    
					
    Hi,
    

    I would recommend you use separate converters for your application. If your input voltage is 5V or more, the LT3471 will require special care with soft-start. That is in order to ensure the switch is not subjected to simultaneous high voltage and current during startup. Please refer to the last section of the Soft-Start paragraph on page 7. 
    

    The LT3580 would be a much better part for your application, but yes, it would require two separate parts. 
    

    Depending on your input voltage range there might be other options, better suited for your application.
    

    Cheers!
    

    Dulcevida
    

    

    

    

    

    

    
			
    

		
		
		
		
	
    
	
    
		
    
			
		
    
	
    
	
    
		
						
						
						
						
				
				
		
		
    
			
		
    
	
    

    

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                                 Analog Employees 
                                
                            
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                on Aug 29, 2019 9:15 AM
            
            
												
						in reply to Siddhesh_P
					
									
    
	
    

		
		
    
					
    Depending too on how much output current is needed, you may also check dual output ADP5070 or ADP5071.
    
			
    

		
		
		
		
	
    
	
    
		
    
			
		
    
	
    
	
    
		
						
						
				
						
				
				
		
		
    
			
		
    
	
    

    

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