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LTC7001 PWM High-Side Motor Driver



		

			

									
						Flo1989
					
							

			
				
									
											
							 		
		        	            							
			
			    	
			                    
                
				                on Aug 19, 2021 
				
			
			
		


				
		

		    		    
		    
		    	
			
Hi,




we run into Problems when using the LTC7001 for a Brushed Motor Control. We want control the Input Pin with a 20kHz PWM Signal. We have this Circuit:


 




I already added the TVS Diode from GND to Ts Pin.


The Problem:


The FET has a Qg from 75nC so for PWM i decided to use 100nF Boost Capacitor. But The Gate Voltage will only go up to Ts + 5V.


Then i changed the Boost Capacitor to 1uF now i will have a Gate Voltage of Ts + 12V but with 80% PWM the Driver Stops after some seconds working, will pause a second and remain working. I can't figure out why the driver is stopping.


Can somebody explain this? OV and UV are at Max and Min values. I don't see any Voltage drop on VCC.




Thank you,


Florian

								


				
				
		

			
						
									
									
						
						
			
			
			
			
		


					

			





	










	

	

					



			








	
	
	
	



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													+1
							
			
				
									
							        
            
                                    			
			                            
                        
                on Aug 24, 2021 8:02 AM
            
            
					
    
	
    

		
		
    
					
    Ok, i figured out, that with +5V VCC Supply the Charge Pump can not supply enough current in PWM mode. I changed the VCC Supply to the +12V from the Main Supply. But with the Voltage drop from starting the motor spinning, the LTC7001 don't survived. I then added an SEPIC Converter to supply the LTC7001 with +12V. This was the solution for the problem. I can now drive the Motor with an 20kHz PWM Signal.
    
			
    

		
		
		
		
	
    
	
    
		
    
			
		
    
	
    
	
    
		
						
						
						
						
				
				
		
		
    
			
		
    
	
    

    

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													+1
							
			
				
									
							        
            
                                    			
			                            
                        
                on Aug 24, 2021 8:02 AM
            
            
					
    
	
    

		
		
    
					
    Ok, i figured out, that with +5V VCC Supply the Charge Pump can not supply enough current in PWM mode. I changed the VCC Supply to the +12V from the Main Supply. But with the Voltage drop from starting the motor spinning, the LTC7001 don't survived. I then added an SEPIC Converter to supply the LTC7001 with +12V. This was the solution for the problem. I can now drive the Motor with an 20kHz PWM Signal.
    
			
    

		
		
		
		
	
    
	
    
		
    
			
		
    
	
    
	
    
		
						
						
						
						
				
				
		
		
    
			
		
    
	
    

    

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