Datasheet

EVAL-AD7294
Rev. 0 | Page 3 of 24
EVALUATION BOARD HARDWARE
POWER SUPPLIES
There are two options available for powering the AD7294
evaluation board:
• Using the USB port of a computer
• Using an external power supply
The default option for powering the board is to use the USB
port. This option is selected when K12, K13, and K14 are in
Position A; however, in addition, K10 must be connected to
DV
DD
and AV
DD
x, and K11 must be connected to AV
DD
x and
DAC OUTV+ xx. The 5 V from the USB port is regulated to
3.3 V, which provides power for the USB controller and related
USB circuitry. The USB port also provides the ground connections
for the board.
Alternatively, the other option for powering the board is to use
terminal blocks to enable the use of an external power supply.
This option is selected when K12, K13, and K14 are in Position B;
K10 and K11 can be, but do not have to be, inserted as previously
described.
Extensive ground planes are used on this board to minimize the
effect of high frequency noise interference. There are two ground
planes: the AGND plane and the DGND plane. These planes are
connected at one location close to the AD7294; therefore, it is not
recommended to connect the AGND and DGND planes elsewhere
in the system. The AVDD and DVDD planes are decoupled to the
relevant ground plane using 10 µF and 0.1 µF ceramic capacitors
connected to the AD7294.
The AD7294 device requires three power supply inputs: the
AV
DD
, DV
DD
, and V
DRIVE
. The analog and digital supplies are
independent of each other. The AV
DD
and DV
DD
supplies should
be to tied to the same supply and can be powered from 4.5 V to
5.5 V. The V
DRIVE
supply can be power from 2.7 V to 5.5 V and
can be different from the supply on AV
DD
and DV
DD
. The
evaluation board also contains an independent analog power
supply for the operational amplifiers.