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ADP2442 Recommended for New Designs
The ADP2441 / ADP2442 is a constant frequency, current mode control, synchronous, step-down, dc-to-dc regulator that is capable of driving loads of up...
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ADP2442 on Analog.com

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ADP2442 shutdown output after some seconds



		

			

									
					    staticboards
					
							

			
				
									
											
			
			
				
    
			
			
			    	
			                    
                
				                on Jan 30, 2018 
				
			
			
		
    

				
		
    
		    		    
		    
		    	
			
    Hi!
    
 
    We are evaluating the ADP2442 ic. Our prototype is a basic dc dc converter, from 24V to 5V
    
 
    This is the schematic (basically a copy&paste of the reference design):
    
 
    
 
    If we connect the pin 6 (SYNC/MODE) to gnd (pulse skip mode), the circuit seems to work. We have 5V and we can supply current for a test load.
    
 
    But if we use the fixed mode (pin 6 to vcc), the circuit works for a couple of seconds, and then, it shutdowns. We were looking for something strange, but at first, we dont see anything.
    
 
    any idea or suggestion?
    
 
    Thank you very much!!!
    
									
			        
		
    

				
						
        

    
    Tags: 
                                            
                 Internal Power Switch Buck Regulators
                
                                                    
                 adp2442
                
                                                    
                 power
                
                                                    
                 dcdc
                
                                                    
                 Step-Down (Buck) Regulators
                
                                
            
    
    
    

		
    
			
						
									
									
						
						
			
			
			
			
		
    

        
        

					
    
			
    


    
















    
	
    
	
    
					



			








	
	
	
	



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      •  Analog Employees  
      
            
						
                            
            
            				
            
                on Feb 6, 2018 2:06 AM
            
            
					
      
	
      

		
		
      
					
      I noticed that the AGND and PGND are connected together through pin13, that should be fine. Then the layout has no strange things.
      
 
      Did you encounter this "shut down" issue on every unit, or just this particular one?
      
 
      For the skip mode, have you tried to draw some load current to see if the ADP2442 can enter into FPWM mode smoothly?
      
 
      For the external LED, since the PGOOD is open-drain and when output is ready, it becomes high-Z. According to the schematic, the LED connection is not correct. Whatever the PGOOD is pulled low or released (high-Z), the LED will not be ON.
      
			
      

		
			
	      

		
		
	
      
	
      
		
      
			
		
      
	
      
	
      
		
						
						
				
						
				
				
		
		
      
			
		
      
	
      

      

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													0
							
			
				
									
							        
			
			
			
      •  Analog Employees  
      
            
						
                            
            
            				
            
                on Feb 6, 2018 2:06 AM
            
            
					
      
	
      

		
		
      
					
      I noticed that the AGND and PGND are connected together through pin13, that should be fine. Then the layout has no strange things.
      
 
      Did you encounter this "shut down" issue on every unit, or just this particular one?
      
 
      For the skip mode, have you tried to draw some load current to see if the ADP2442 can enter into FPWM mode smoothly?
      
 
      For the external LED, since the PGOOD is open-drain and when output is ready, it becomes high-Z. According to the schematic, the LED connection is not correct. Whatever the PGOOD is pulled low or released (high-Z), the LED will not be ON.
      
			
      

		
			
	      

		
		
	
      
	
      
		
      
			
		
      
	
      
	
      
		
						
						
				
						
				
				
		
		
      
			
		
      
	
      

      

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