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ADN2892 Not Recommended for New Designs
The ADN2892 is a 4.25 Gbps limiting amplifier with integrated loss of signal (LOS) detection circuitry and a received signal strength indicator (RSSI)...
Datasheet
ADN2892 on Analog.com

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ADN2892: SQUELCH pull-down value?

		            
		

			

									
					    vdd
					
							


			
				
									
											
			
			
				
    
			
			
			    	
			                    
                
				                on Jul 21, 2017 
				
			
			
		
    
		
     
				
		
    
		    		    
		    
		    	
			
    Hi,
    
 
    I'm working with the ADN2892 for interfacing to a PIN diode with an integrated TIA.  The datasheet notes that you can use the LOS output to drive the SQUELCH input, which would disable the amplifier output when there is no optical signal input.  I have the ADN2892 evaluation board, and I've added a pullup from LOS to +3.3V.  I've verified that LOS is operating correctly, pulling to the correct level based on the optical input.
    
 
    However, the SQUELCH pin is said to have a 100kohm pull down to GND according to the datasheet.  I've tried pulling this up to +3.3V with as little as 30 ohms, but it's stuck at GND.  Using the switch on the evaluation board, the SQUELCH pin has the correct behavior, but that's being pulled directly to +3.3V.  Am I missing something here or is the datasheet's description of this pin incorrect?
    
 
    Thanks so much!
    
 
    -John
    
									
			        
		
    

				
						
        

    
    Tags: 
                                            
                 adn2892
                
                                                    
                 Fiber Optic Data
                
                                                    
                 Optical Limiting Amplifiers
                
                                
            
    
    
    

		
    
			
						
									
												
			
			
                        
                                    
                        
                        
                        
            
			            
						
						
			
			
			
			
		
    

        
        

					
    
			
    


    
















    
	
    
	
    
					



			


				
	









	
      
	

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      •  Analog Employees  
      
            
						
                            
            
            				
            
                on Jul 24, 2017 12:56 PM
            
                                    
					
      
	
      

		
		
      
					
      Dear John,
      
 
      We are not 100% sure what you did and what you have observed.
      
 
      Would you please elaborate "I've tried pulling this up to +3.3V with as little as 30 ohms, but it's stuck at GND."
      
 
      Your experiment schematic might be useful for us to fully understand your observation.
      
 
      Did you control the ADN2892 SQUELCH input by using ADN2892 LOS output directly?
      
 
      If yes, did you connect ADN2892 LOS to SQUELCH pins directly with a fly line, after taken off switch S3?
      
 
      Please refer to Fig. 4 of AN-761 for the evaluation board circuit schematic details.
      
 
      One ADN2892 evaluation board will be useful to do these experiment. Glad you have one.
      
 
      Would you please share us your PD+TIA+ADN2892 schematic design for a review?
      
 
      To protect your proprietary design information, you may send your further questions
      
 
      and your PD+TIA+ADN2892 design schematic to me: dongfeng.zhao@analog.com.
      
 
      Best Regards,
      
 
      Dongfeng
      
			
      

		
			
	      

		
		
	
      
	
      
		
      
			
		
      
	
      
	
      
		
						
						
				
						
				
				
		
		
      
			
		
      
	
      

      

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