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Original question:

TPS3705: Pulse width value specified by Texas instrument

TPS3705: How to latch WDO/

TISL
Expert 4630 points
Part Number: TPS3705

Dear e2e,

Could you confirm that WDO/ is a high impedance output?

My customer would need to latch the WDO/ to not get the cycling phenomena (explained here )

Do we have other supervisor? or other trick than the App Note SNVA837?

Regards,

  • +1
    TI__Genius 9700 points

    Hello,

    WDO is not high impedance and is active low. 

    We do have a latching watchdog and supervisor device to release early next year. To help us understand the opportunity, do you know the production timeline for the customer?

    Are you able to provide the timing requirements for WD?

    Thanks,

    Walter

  • 0
    Prodigy 170 points

    Hello, 

    Production of the new prototypes is scheduled for the end of the year.

    With the following diagram, the WDO/ output is at 3.3V when the WDI signal oscillates and the WDO/ output falls to 0V when the WDI signal no longer oscillates.

    The WDO/ signal remains at 0V, it doesn't rise again. Is it a normal behavior ?

    

    

    Thank you 
    

    

    
			
    

		
		
		
		
	
    
	
    
		
    
			
		
    
	
    

	            
                	
	
    
				
		                
                
                
                
                
                
                
        		
		
				
    
			
		
    
		
		 
		
		
     
    
	
    

    
			
    
			
    
		
    

		
    
	
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						in reply to nicolas ladaurade
					
									
    
	
    
	                                    
                      
    
                        
                          TI__Genius
                        9700 points
                      
    
                          
                   		
		
    
					
    Hello Nicolas,
    

    WDO/ should output periodic pulses when WDI is not oscillating. If WDI is disconnected the watchode will be disabled.
    

    WDO/ and RESET/ are CMOS outputs and should not be connected together. This may be causing your issue.
    

    Thanks,
    

    Walter
    
			
    

		
		
		
		
	
    
	
    
		
    
			
		
    
	
    

	            
                 	
	
    
				
		                
                
                
                
                
                
                
        		
		
				
    
			
		
    
		
		 
		
		
     
    
	
    

    
			
    
			
    
		
    

		
    
	
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