JAJSGG2C October 2018 – June 2019 ADS125H02
The ADC includes a precision 2.5-V reference. The REFENB bit of the REF register enables the reference (default = off). Program the reference multiplexer bits RMUXP[1:0] and RMUXN[1:0] to 00b to select the internal reference. A 10-µF capacitor is required between the REFOUT and AGND pins to filter the reference noise. The capacitor is not required if the internal reference is not used. Always enable the internal reference if using the current sources.
REFOUT is the buffered reference output and AGND is the reference return. For good voltage regulation and to minimize ground noise, use a star-layout connection for the reference return and make the return connection close to the AGND pin.
Be aware of AVDD inrush current when the reference is enabled. The inrush current is a result of charging the 10-µF REFOUT capacitor. Also, be aware of the reference voltage stabilization time when starting a conversion or when calibrating the ADC.