ZHCSFZ2 February 2017 DAC8775
PRODUCTION DATA.
There are three possible hardware power supply configurations for the DAC8775: the internal DC/DC provides both positive and negative supply voltages, the internal DC/DC provides only one of the supply voltages with an external supply provided on the other, or the internal DC/DC is not used at all and external supply voltages are provided for both positive and negative supply voltages. Simple illustrations for each case are shown below.
Figure 135. DAC8775 With Dual Supplies from Internal DC/DC
Figure 136 illustrates using a single supply from the DAC8775 internal DC/DC and the other supply from an external source. In this example the VNEG_IN_x supply is the input being supplied by an external supply, or ground for unipolar output spans. A similar scheme could be used if VPOS_IN_x was supplied by an external supply and VNEG_IN_x was supplied by the internal DC/DC.
Figure 136. DAC8775 With Single Supply from Internal DC/DC
The scheme in Figure 137 should be used if the internal DC/DC is not used at all and external supplies are selected for VPOS_IN_x and VNEG_IN_x. When using external supplies for VPOS_IN_x it is important that VPOS_IN_x, PVDD, and AVDD nodes are tied to the same voltage potential with the same ramp-rate.
Figure 137. DAC8775 with External Supplies