ADS124S06: VBAISの分割抵抗について

Hi Masamitsu Hayashi,

Welcome to the E2E forum!  E2E is an English language forum only, so please translate prior to posting.  The bias voltage is a simple voltage divider.  It is meant not as a precision source but rather a simple bias voltage to place sensors, such as a thermocouple, into the correct measurement input range for the ADC.  The voltage output from the resistor divider is buffered, but the buffer has a relatively large output impedance (350 Ω typical at room temperature).  So the buffer cannot drive a lot of current without affecting the bias voltage at the device pin. 

Generally silicon resistors are not that precise but are well matched within a process.  The precise value of R was not given from the design team, nor was the tolerance.  The term 'R' is there to give you an idea of how the bias voltage is created.  Also note that the bias voltage is between AVDD and AVSS.  If you need a precise bias voltage with a low output impedance, then you should use an external bias voltage source.

Best regards,

Bob B