The AD7191 is a low noise， complete analog front end for high precision measurement applications. It contains a low noise， 24-bit sigma-delta （Σ-Δ） ADC. The on-chip low noise gain stage means that signals of small amplitude can be interfaced directly to the ADC. It contains two differential analog inputs. The part also includes a temperature sensor that can be used for temperature compensation. For ease-of-use， all the features of the AD7191 are controlled by dedicated pins. The on-chip PGA has a gain of 1， 8， 64， or 128， supporting a full-scale differential input of ±5 V， ±625 mV， ±78 mV， or ±39 mV. The output data rate can be programmed to 10 Hz， 50 Hz， 60 Hz， or 120 Hz. Simultaneous 50 Hz and 60 Hz rejection is obtained when the output data rate is set to 10 Hz or 50 Hz; 60 Hz only rejection is obtained when the output data rate is set to 60 Hz. The AD7191 can be operated with the internal clock， or an external clock can be used. The part operates with a power supply of 3 V to 5.25 V. It consumes a current of 4.35 mA. It is available in a 24-lead TSSOP package.