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LT6237 Recommended for New Designs
The LT6236/LT6237/LT6238 are single/dual/quad low noise, rail-to-rail output op amps that feature 1.1nV/√Hz input referred noise voltage density and...
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LT6237 on Analog.com

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limited Input Voltage Range - Model or DataSheet error?

		
	
				

			

									
					    JFeSSTS
					
							

            
            			
				
									
											
			
			
				
			
			
			    	
			                    
                
				                on Jan 31, 2025 
				
			
			
		

		
		                     
				
        		

		    
		    		    

		      		            		        
Category: Datasheet/Specs

    		        		            		    
Product Number:  LT6237 

    		        		    		    

		    		    
		    			

			    
5241.LT6237_sim.asc


Hi,


We planned to use the LT6237 amplifier as Buffer, supplied in -/+3.3V w/ Input Voltage range (VCM) = -2.5V/+2.5V. Which seems to be not an issue according to the Datasheet.


 


However when simulating it w/ LTSpice, the Input common range seems to be much lower.


Here is my test bench (unity gain config w/ DC sweep input from 0V to 3.3V, and the amplifier is supplied here in +3.3V/0V as described in Datasheet)


 


As you can see on these simulation plots, the input range seems to be limited to 1.5V to 2.3V


 


Is there any error in the model? Or wrong Datasheet?


Thanks for your answer.


Best Regards


Julien

			

			
									
		                                 
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    •  Analog Employees  
    
            
						
                            
            
            				
            
                on Jan 31, 2025 1:05 PM
            
            
						
			            		
    
		
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    Hi  ,
    

    Good question. In general, I would lean toward the datasheet. I can move this to the amplifier forum, where you would get a more definitive answer.
    

    mike
    
			
    

		
			
	      

		
		
	
    
	
    
		
    
			
		
    
	
    
	
    
		
						
						
				
						
				
				
		
		
    
			
		
    
	
    

    

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    •  Analog Employees  
    
            
						
                            
            
            				
            
                on Feb 3, 2025 2:39 AM
            
            
						
			            		
    
		
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    Hello ,

    Since the circuit is configured as a buffer (input = output), the simulated input voltage range should be about from 1.25V to 2.54V as shown below. The value that can be seen on the output is essentially the input voltage range (with proper consideration to the output voltage range).
     

    If the input voltage is below 1.25V or above 2.54V, the output already clips as shown on the simulation above. These values are already quite near to the specified input voltage range on the data sheet:
     

    Regards,
    Paul
    
			
    

		
			
	      

		
		
	
    
	
    
		
    
			
		
    
	
    
	
    
		
						
						
				
						
				
				
		
		
    
			
		
    
	
    

    

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