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ADuM4121 Production
The ADuM4121/ADuM4121-1 are 2 A isolated, single-channel drivers that employ Analog Devices, Inc.’s iCoupler® technology to provide precision isolation...
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ADuM4121 on Analog.com

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ADUM4121WHB1Z shoot through

		
	
				

			

									
					    JimmyH
					
							

            
            			
				
									
											
			
			
				
    
			
			
			    	
			                    
                
				                on Jul 18, 2025 
				
			
			
		
    
		
		                    	    
    
        	    
    Thread Summary
    
                The user is experiencing a low voltage square wave on the negative side of the drive output with the ADUM4121WHB1Z evaluation board, which may indicate shoot through. The support engineer suggests checking for ground loops and using isolated or differential probes to measure the high-side gate voltage. The user provided scope captures showing noise on other channels when the daughter board is installed, and the issue worsens with high voltage. The support engineer requested a scope capture without the power daughter cards to further diagnose the problem.
                        	    
    
                
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    Category: Hardware
    
    		        		            		    
    Product Number:  adum4121WHB1Z, adum4121 
    
    		        		    		    
    
		    		    
		    			
    
			    
    I am currently using the ADUM4121WHB1Z evaluation board with the Wolfspeed system. Without the daughter boards installed for the mosfets, I see a low voltage squarewave on the negative side of the drive output. It looks like when I try drive the half bridge, it is creating shoot through. I had to replace the drivers a couple times over a shoot through event. Is there anything else I should be looking at?
    
			
    
			
									
		                             
                        

    
    
                                            
                 hardware
                
                                                    
                 Digital Isolation Technology
                
                                                    
                 Isolated Gate Drivers
                
                                                    
                 ADuM4121
                
                                                    
                 adum4121WHB1Z
                
                                
            
    
    
    
		
    

				
				        
        		
    
			
						
									
												
			
			
                        
                                    
                        
                        
                        
            
			            
						
						
			
			
			
			
		
    

        
        
        
    
					
    
			
    


    
















    
	
    
	
    
					



			


				
	









	
      
	

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      •  Analog Employees  
      
            
						
                            
            
            				
            
                on Jul 21, 2025 4:16 AM
            
            
						
			            		
      
		
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      Hi JimmyH,

      Thanks for getting in touch regarding the ADUM4121WHB1Z. 

      To better understand the issue could you please provide more information on what net of the circuit are you probing, and provide a scope capture of the waveform showing the square wave?
      What Wolfspeed system are you using, and how are you driving the PWM signals on connector P2?

      Thanks,
      Luca
        


      
			
      

		
			
	      

		
		
	
      
	
      
		
      
			
		
      
	
      
	
      
		
						
						
				
						
				
				
		
		
      
			
		
      
	
      

      

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                on Jul 21, 2025 11:04 AM
            
            
												
						in reply to LMartini
					
										
			            		
        
		
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        Hi Luca,
        

        Yes, I am using the SpeedVal kit Three-phase motherboard. Yes I am connecting to it as normal. I am not using the processor daughter card, but connecting single ended pwm to the PWM monitor conn11. I have made no modifications to the ADUM4121WHB1Z, but I have had to replace the drivers a couple times. We are running at 6khz with a deadtime of 10uS. We are using to create a full bridge rectifier if that helps. Channel one is the output of the Driver. One picture for low side and one for High side.
        

           
        

        

        Thanks,
        

        Jimmy
        
			
        

		
			
	      

		
		
	
        
	
        
		
        
			
		
        
	
        
	
        
		
						
						
				
						
				
				
		
		
        
			
		
        
	
        

        

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        •  Analog Employees  
        
            
						
                            
            
            				
            
                on Jul 22, 2025 5:35 AM
            
            
												
						in reply to JimmyH
					
										
			            		
        
		
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        Hi Jimmy,

        I think you might have some setup issue here, such as ground loop through GND of scope probes or something else, I don't believe this ripple is coming from the gate driver.
        Are you using isolated probes or differential probes to measure high side gate voltage?   
        Can you take the same scope capture without the power daughter cards please?
        I would like to see the output of the gate driver when the power transistor is removed.

        Thanks,
        Luca

        
			
        

		
			
	      

		
		
	
        
	
        
		
        
			
		
        
	
        
	
        
		
						
						
						
						
				
				
		
		
        
			
		
        
	
        

        

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                on Aug 1, 2025 1:41 PM
            
            
												
						in reply to LMartini
					
										
			            		
          
		
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          Luca, 
          

          Thanks for responding. I was pulled to other things. Below I have taken better screen shots. One is with no Daughter board installed and the other is with the daughter board installed but without High voltage. If I turn on any high voltage, it gets worse.
          

          No daughter card  Daughter card installed, no high voltage
          

          In the first image you can see that the Rise and fall are creating noise on the other 3 channels. This is the output of the driver board. In the second image, you can see this noise gets worse if I install the daughter board. With out these, there is no noise. I did have a shoot through that damaged a couple driver boards and I have replaced the ADUM4121 for both boards and High and Low side. If there was something else I should replace it would be greatly appreciated.
          

          Thanks,
          

          Jimmy
          
			
          

		
			
	      

		
		
	
          
	
          
		
          
			
		
          
	
          
	
          
		
						
						
				
						
				
				
		
		
          
			
		
          
	
          

          

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