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OP297



		

			

									
					    M1A1abms
					
							

			
				
									
											
			
			
				
    
			
			
			    	
			                    
                
				                on Jan 25, 2021 
				
			
			
		
    

				
		
    
		    		    
		    
		    	
			
    I have built a voltage amplify circuit with OP297GS.
    

    But sometimes, circuit does not work right, and that will not back to normal.
    

    There is an potentiometer before the Input pin (pin2), but I can't adjust output voltage.
    

    So, I exchange that OP297 with new one, then the circuit work right.
    

    

    I wish you to teach me. 
    

    1.
    

    On the datasheet, Output Voltage Swing Condition is RL=2kΩ to RL=10kΩ.
    

    Can I use OP297 out of these conditions?
    

    

    2.
    

    On the data sheet, AC performance is written as below.
    

    "the OP297 displays excellent responce with 1000 pF loads."
    

    CL=1000pF
    

    Can I use bigger capacitance than 1000pF? 
    

    

    I'm afraid these thing is the key of my problem.(or the part is replica...)
    

    Thank you!! 
    
								
    

				
				
		
    
			
						
									
									
						
						
			
			
			
			
		
    

        
        

					
    
			
    


    


	
    
		
	
    















    
	
    
	
    
					



			


				
	









	
      
	

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      •  Analog Employees  
      
            
			                            
                        
                on Jan 27, 2021 6:00 AM
            
            
					
      
	
      

		
		
      
					
      Hi,
      

      It would help if you can post your schematic.
      

      To answer your questions:
      

      1. The Output Swing was specified at specific range of load and that is 2k to 10K ohms. Approaching infinity ohms load will require less current and your output swing more likely same as to 10k performance. However, if your load is getting lower, this will require more current drive and will result to pull on voltage output swing.
      Please refer to Figure 21, page 7 of the data sheet.
      

      2. The higher the capacitive load to drive, the more the output become unstable. This is shown on Figure 26 and Figure 27, page 9 of the data sheet. As you can see, the 1000pF load has higher over shoot and longer ringing than the 100pF load.
      

      Hope this helps.
      

      Thanks and regards.
      
			
      

		
		
		
		
	
      
	
      
		
      
			
		
      
	
      
	
      
		
						
						
				
						
				
				
		
		
      
			
		
      
	
      

      

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