EVAL-AD7124-4SDZ User Guide
UG-855
Rev. 0 | Page 7 of 29
POWER SUPPLIES
The evaluation board requires that an external power supply—
either a bench top supply or a wall wart (dc plug) supply—be
applied to J3 or J5 (see Table 3 for more information). Linear
regulators generate the required power supply levels from the
applied V
IN
rail. The regulators used are the
ADP1720-3.3
(U7)
and the
ADP1720
(U4), which supply 3.3 V and 1.8 V,
respectively, to AV
DD
of the ADC. The 3.3 V
ADP1720
(U10)
delivers 3.3 V to the IOV
DD
pin of the
AD7124-4
.
When a split power supply is used, the AV
SS
voltage must be
applied from an external source via Connector J9. AV
DD
and
IOV
DD
can also be provided via Connector J9. However, the 7 V
to 9 V supply is still required because the on-board reference
(
ADR4525
) is supplied from this power supply.
Each supply is decoupled at the point where it enters the board
and again at the point where it connects to each device (see the
schematics shown in Figure 26 to Figure 29 to identify
decoupling points).
SERIAL INTERFACE
The
EVAL-AD7124-4SDZ
evaluation board connects via the
serial peripheral interface (SPI) to the Blackfin®
ADSP-BF527
on the
EVAL-SDP-CB1Z
. There are four primary signals: CS,
SCLK, DIN, and DOUT/RDY (all are inputs, except for
DOUT/RDY, which is an output).
To operate the
EVAL-AD7124-4SDZ
in standalone mode, the
AD7124-4
serial interface lines can be disconnected from the
120-pin header by removing the 0 Ω links, R9 through R13. The
test points can then be used to fly-wire the signals to an alternative
digital capture setup.
ANALOG INPUTS
The
EVAL-AD7124-4SDZ
primary analog inputs can be applied
in two ways:
•
Using J6 and J11, the green screw in terminal connectors
•
Using the A0 and A1 SMB/SMA footprints on the
evaluation board, which connect to the AIN4 and AIN5
analog inputs.
The
AD7124-4 EVAL+ Software
is set up to analyze dc inputs to
the ADC.
Table 3. Required External Power Supply
1
Power Supply
(V
IN
) Applied To Voltage Range
Function
J3
7 V to 9 V
Bench top supply to the evaluation board. Supplies LDOs that create the 3.3 V and 1.8 V rails. It also
supplies the
ADR4525
external reference. Ensure that LK2 is set to Position A when the external
power supply is applied to this connector.
J5
7 V to 9 V
Wall wart (dc plug) supply to the evaluation board. Supplies LDOs that create the 3.3 V and 1.8 V rails.
It also supplies the
ADR4525
external reference. Ensure that LK2 is set to Position B when the external
power supply is applied to this connector.
1
Only a single supply is required, either J3 or J5. This supply can be selected using LK2.
Содержание EVAL-AD7124-4SDZ
Страница 21: ...EVAL AD7124 4SDZ User Guide UG 855 Rev 0 Page 21 of 29 13304 027 Figure 27 Schematic Power Supply ...
Страница 22: ...UG 855 EVAL AD7124 4SDZ User Guide Rev 0 Page 22 of 29 13304 028 Figure 28 Schematic Regulators ...
Страница 23: ...EVAL AD7124 4SDZ User Guide UG 855 Rev 0 Page 23 of 29 13304 029 Figure 29 Schematic SDP ...
