AnsweredAssumed Answered

AD7192 reference voltage

Question asked by ccenten on Jun 17, 2014
Latest reply on Jun 29, 2014 by ChrisD.Rama

Hi,

 

I am using the AD7192 for a load cell application. I am following the reference note CN0119 (http://www.analog.com/static/imported-files/circuit_notes/CN0119.pdf). In most example applications, there reference voltage is derived from the AVdd voltage supplying the load cells. In my application, the load cell sensitivity is such that the at 5V, the full range output is only 5mV. Therefore, by using 5V as the reference voltage, the full input range would be ~39mV, far larger than my 5mV full scale value. In this situation, is there a benefit to reducing the reference voltage so that the full range of the ADC input is closer to the full range of my signal? Will this improve the resolution, or is there some other tradeoff I am not seeing. I understand that the reference on the AD7192 is unbuffered, therefore, my plan is to feed a resistor divider from the load cell supply through an op amp buffer to the ref+ input. This should maintain the ratiometric nature of the system while improving the resolution. Any feedback on this configuration would be much appreciated.

 

Thank you!

Outcomes