• State Verified Answer
  • +1 person also asked this people also asked this
  • Replies 1 reply
  • Subscribers 16 subscribers
  • Views 212 views
  • Users 0 members are here
Options
Related 

        

            Post
             Go back to editing
        

    

    


    

    









		











	
	
			
	
			
		
	
	
		

		
ADT7420 question about pull-up resistors!



		

			

									
						jgirgis
					
							

			
				
									
											
							 		
		        	            							
			
			    	
			                    
                
				                on Oct 16, 2021 
				
			
			
		


				
		

		    		    
		    
		    	
			
Hi 


I am making a board that has the ADT7420 on it.


I want it to be the slave device my master device to be many meters away.


    

  1. Where do I put the pullup resistors? On the master or slave board?
    2. 

  2. For the CT and INT pins are the pullups optional?

      

    1. If not, is it best to put their pull ups on a master or slave board?
      2. 

    

    3. 

  3. For decoupling many meters away should I have a low pass filter?
    4. 

  4. For the i2C communication pins could I have resistor terminations for the wires that are up to a meter away? Will that interfere with the pullups?
    5. 



Thanks

								


				
				
		

			
						
									
									
						
						
			
			
			
			
		


					

			





	










	

	

					



			


				
	









	
    
	

  • 
	
    



	
			
		
	



    
	
    
		
    
							
					
    
		
    
			
													+1
							
			
				
									
							        
            
                                                                                                        
      
                            
    • 
                                 Analog Employees 
                                
                            
      • 
                        
     
                                                           			
			                            
                        
                on Oct 25, 2021 8:44 AM
            
            
					
    
	
    

		
		
    
					
    Hi,
    

    See answers below:
    

    1. It's advisable to put the pullup resistor near the master just in case the cable might be disconnected. 
    

    2. INT and CT pins are open-drain output, thus they both require a 10kohm pull up resistor to VDD. Make sure that ADT7420 is fully powered up to VDD before reading INT and CT data.
    

    3. Decoupling cap must be placed as close as possible to minimize the line inductance between the decoupling cap and device.
    

    Can you share your schematics and the application you are trying to do here??
    

    

    Regards,
    

    Marymae
    
			
    

		
		
		
		
	
    
	
    
		
    
			
		
    
	
    
	
    
		
						
				
						
						
				
				
		
		
    
			
		
    
	
    

    

    •