Products Mentioned

AD725 Production
The AD725 is a very low cost general purpose RGB to NTSC/ PAL encoder that converts red, green and blue color component signals into their corresponding...
Datasheet
AD725 on Analog.com

Thread Details

  • State Verified Answer
  • +1 person also asked this people also asked this
  • Replies 14 replies
  • Subscribers 82 subscribers
  • Views 3717 views
  • Users 0 members are here
Options
 
Related Content

        

            Post
             Go back to editing
        

    

    


    

    









		


















	
	
			
	
			
		
	
	
		

	    
	    
	    		
AD725 input crystal frequency options

		
	
				

			

									
					    VEGETA
					
							

            
            			
				
									
											
			
			
				
    
			
			
			    	
			                    
                
				                on Nov 4, 2022 
				
			
			
		
    
		
		                    	    
    
        	    
    Thread Summary
    
                The user asks if the AD725 can accept 3.3V crystal signals for 4FSC, particularly for NTSC and PAL. The final answer confirms that a 3.3V oscillator should work as the Vhi_min is 2V. The user is advised to use a 10k pull-up resistor to 3.3V for the OE pin to ensure the oscillator output is enabled. The AD725 evaluation board schematic is referenced for a similar mechanical switch setup, and the use of MEMS oscillators is discouraged due to potential jitter issues.
                        	    
    
                
                     AI Generated Content
                
    	    
    
             
				
        		
    
		    
		    		    
    
		      		            		        
    Category: Hardware
    
    		        		            		    
    Product Number:  AD725 
    
    		        		    		    
    
		    		    
		    			
    
			    
    Hello
    

    

    I found that AD725 requires TTL levels for 4FSC but I could not find NTSC crystal which is 5v! so I thought will a 3.3v crystal work fine??
    

    

     
    

    

    as seen in my picture, the circuit is simple. I have a SP3T switch (or any mechanism) that feeds 0v for choosing PAL, 3,3v for NTSC or just another throw for auto detection (circuit not shown here). this circuit needs more tuning but you get the idea.
    

    

    I really need very easy and stable solution which doesn't require tuning...
    

    

    so can AD725 accept 3.3v crystal signals?
    

    

    what crystals do you suggest? I need some part numbers please since finding them is very hard now.
    

    

    thanks
    
			
    
			
									
		                             
                        

    
    
                                            
                 Video Products
                
                                                    
                 hardware
                
                                                    
                 Video Encoders
                
                                                    
                 ad725