EVM Analog Interface
7
SBAU291 – November 2017
Copyright © 2017, Texas Instruments Incorporated
ADS8168EVM-PDK
2.1
ADS8168 Internal Reference and EVM Onboard Reference
The ADS8168 device incorporates an internal 4.096-V reference. Upon power up, the device uses this
configuration. In order to select the external reference, the user must select the external reference mode
by writing to the configuration register of the ADS8168. Next, power up the external reference by installing
a shunt on JP1, labeled "AVdd"; and connect the reference to the ADS8168 by installing a shunt on JP3,
labeled "Ref". Input is now 0 V to 5 V. In this mode, note that the reference is limited by the internal
reference buffer of the ADS8168 to AV
DD
– 0.3 V. A 5-V reference voltage is possible due to the operation
of AV
DD
at 5.3 V.
Figure 3. REF5050 5.0-V External Reference Source
