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CCS：ads1220 Is it possible to use the internal 1mA excitation source of ads1220 when powering the pressure sensor (bridge)

user6349600
Prodigy 20 points

Tool/software: Code Composer Studio

See manual p58


ADS1220
ZHCSBH5C –MAY 2013–REVISED AUGUST 2016 www.ti.com.cn
Copyright © 2013–2016, Texas Instruments Incorporated


9.2.3 Resistance bridge measurement
The device has multiple functions to easily implement proportional bridge measurements (for example, a PGA with a gain of up to 128, multiple buffered differential reference input
Low-side power switch).


Figure 82. Resistance bridge measurement





								


				
				

				
			

		

			
						
									
                			    			                        
						
						
			
			
						
			                        
			
			
				
			  
			

			     
			

		


				    			

						
















	

	

					
    
	
    





		
	
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                          TI__Mastermind
                        35561 points
                      
    
                          
                   		
		
    
					
    Hi User,
    

    Yes this is possible, and is useful for long excitation/signal wires where IR drops are possible. For most bridge circuits however, those with shorter excitation lines or Kelvin connections (6-wire bridge), voltage excitation is most common. This excitation voltage is then also used for the differential reference voltage such that it is ratiometric.
    

    This is also possible for current excitation, though you would need to pass the current through a reference resistor since the absolute magnitude of the IDAC current can vary a lot (see the datasheet for more info on this). The reference resistor would need to be sized such that the differential bridge output voltage is less than the voltage across the reference resistor. You must also respect IDAC headroom requirements, again as per the datasheet
    

    -Bryan
    
			
    

		
		
		
		
	
    
	
    
		
    
			
		
    
	
    

	            
                 	
	
    
				
		                
                
                
                
                
                
                
        		
		
				
    
			
		
    
		
		 
		
		
     
    
	
    

    
			
    
			
    
		
    

		
    
	
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