JAJS398F January 2009 – April 2018 DAC7568 , DAC8168 , DAC8568
PRODUCTION DATA.
The internal reference in the DAC7568, DAC8168, and DAC8568 is disabled by default for debugging, evaluation purposes, or when using an external reference. The internal reference can be powered up and powered down using a serial command that requires a 32-bit write sequence (see the Serial Interface section), as shown in Table 20 and Table 22. During the time that the internal reference is disabled, the DAC functions normally using an external reference. At this point, the internal reference is disconnected from the VREFIN/VREFOUT pin (3-state output). Do not attempt to drive the VREFIN/VREFOUT pin externally and internally at the same time indefinitely.
There are two modes that allow communication with the internal reference: Static and Flexible. In Flexible mode, DB19 must be set to '1'.