• State Verified Answer
  • Replies 1 reply
  • Subscribers 43 subscribers
  • Views 268 views
  • Users 0 members are here
Options
Related 

        

            Post
             Go back to editing
        

    

    


    

    









		











	
	
			
	
			
		
	
	
		

		
AD9237-40 mode2 pin threshold



		

			

									
						Terumasa
					
							

			
				
									
											
							 		
		        	            							
			
			    	
			                    
                
				                on Sep 11, 2014 
				
			
			
		


				
		

		    		    
		    
		    	
			
Hello

 
Please let me know about the threshold of mode pin in AD9237-40.

 
Datasheet  P.20 describes below but does not describe threhold.

 
Mode2     ;  Span ; Power scaling

 
AVDD          ;   1; Disabled

 
2/3 AVDD    ;   1; Enabled

 
1/3 AVDD    ;   2 ;Enabled

 
AGND          ; 2  ;Disabled

 
We would like to use Span factor 1 and power scaling enable.

 
But, board space is too short and it is difficult to make 2/3 AVDD from AVDD(3.3V).

 
So, if possible, we would like to supply 2.5V (another power rail)  to MODE2 pin.

 
As the result of our test,  Span factor 1 and power scaling enable is set by voltage less than 2.6V.

 
Could you give me your advice if there is any problem ?

 
Regards,

 
Terumasa

								


				
				
		

			
						
									
									
						
						
			
			
			
			
		


					

			





	

		
	















	

	

					



			








	
	
	
	



Parents
	
    
	

  • 
	
    



	
			
		
	



    
	
    
		
    
							
					
    
		
    
			
													0
							
			
				
									
							        
            
                                                                                                        
      
                            
    • 
                                 Analog Employees 
                                
                            
      • 
                        
     
                                                           			
			                            
                        
                on Sep 21, 2017 6:38 AM
            
            
					
    
	
    

		
		
    
					
    Hi Terumasa-san,
    
 
    Thank you for using the AD9237.
    
 
    Applying 2.5V to the MODE2 pin will not damage the part as long as the AD9237 is powered up before the 2.5V source.
    
 
    From your testing, you have about 100mV margin at 2.5V. To increase your margin, you could increase AVDD to 3.6V. This would give you another 2/3 * 300mV = 200mV margin. You could also add some series resistance to your 2.5V source.
    
 
    Ultimately you will need to ensure that MODE2 = 2.5V passes your internal system/quality requirements, but in any case MODE2 = 2.5V will not be a damage risk problem for AD9237 as long as the ADC is powered up before the 2.5V is applied.
    
 
    Thank you.
    
 
    Doug
    
			
    

		
		
		
		
	
    
	
    
		
    
			
		
    
	
    
	
    
		
						
				
						
						
				
				
		
		
    
			
		
    
	
    

    

    • 

	




Reply

    


  • 
	
    



	
			
		
	



    
	
    
		
    
							
					
    
		
    
			
													0
							
			
				
									
							        
            
                                                                                                        
      
                            
    • 
                                 Analog Employees 
                                
                            
      • 
                        
     
                                                           			
			                            
                        
                on Sep 21, 2017 6:38 AM
            
            
					
    
	
    

		
		
    
					
    Hi Terumasa-san,
    
 
    Thank you for using the AD9237.
    
 
    Applying 2.5V to the MODE2 pin will not damage the part as long as the AD9237 is powered up before the 2.5V source.
    
 
    From your testing, you have about 100mV margin at 2.5V. To increase your margin, you could increase AVDD to 3.6V. This would give you another 2/3 * 300mV = 200mV margin. You could also add some series resistance to your 2.5V source.
    
 
    Ultimately you will need to ensure that MODE2 = 2.5V passes your internal system/quality requirements, but in any case MODE2 = 2.5V will not be a damage risk problem for AD9237 as long as the ADC is powered up before the 2.5V is applied.
    
 
    Thank you.
    
 
    Doug
    
			
    

		
		
		
		
	
    
	
    
		
    
			
		
    
	
    
	
    
		
						
				
						
						
				
				
		
		
    
			
		
    
	
    

    

    • 





Children
	
No Data