UG-478
Evaluation Board User Guide
Rev. 0 | Page 8 of 40
REFERENCE OPTIONS
The
EVAL-AD7176-2SDZ
includes an external 5 V reference (the
ADR445
) and an internal 2.5 V reference. The default operation
is to use the external reference input, which is set to accept the 5 V
ADR445
on the evaluation board.
The reference used for a conversion is selected by choosing the
reference in the SETUPCONx registers associated with Setup 1,
Setup 2, Setup 3, and Setup 4.
Switch between using the internal reference and external reference
by accessing the
AD7176-2
register map via the evaluation soft-
ware. Figure 3 shows how to select the reference source for
Setup 1, Setup 2, Setup 3, and Setup 4. Figure 4 shows the
ADCMODE register setting that enables the internal reference.
Figure 3. Selecting the Reference Source for
Setup 1, Setup 2, Setup 3, and Setup 4
Figure 4. Turning On the Internal 2.5 V Reference
USING THE ON-BOARD AMPLIFIERS
The
AD7176-2
evaluation board contains three front-end configu-
rations. The
AD8656
is provided for buffering the analog inputs
of the
AD7176-2
. By default, it is configured for a gain of 2, and
the front-end is selected on the evaluation board. The
ADA4940-1
amplifier provides a single-ended to differential driver, whereas
the
AD8475
is configured to operate as an attenuating single-ended
to differential driver. Figure 5 shows the location of the R and C
components on the
AD7176-2
evaluation board. Figure 6 and
Figure 7 highlight the R and C components that are populated
on the board for each amplifier, and Table 5 to Table 7 list the
component values.
Figure 5. Identification of R/C Components for the Amplifiers
1
1035-
034
