Analog Devices AD5696RSDZ, User Manual

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UG-726 EVAL-AD5696RSDZ User Guide
Rev. C | Page 6 of 13
EVALUATION BOARD HARDWARE
POWER SUPPLIES
The EVAL-AD5696RSDZ evaluation board provides an on-board,
3.3 V regulator powered through the USB supply. If a different
supply is required or if the evaluation board is controlled through
the PMOD connector, an external supply must be provided by
the EXTSUP connector. See Table 2 for more details.
Both AGND and DGND inputs are provided on the board. The
AGND and DGND planes are connected at one location close to
the
AD5696R . To avoid ground loop problems, it is recommended
that AGND and DGND not be connected elsewhere in the system.
All supplies are decoupled to ground with 10 µF tantalum and
0.1 µF ceramic capacitors.
LDO RECOMMENDATION
The ADP7118 low dropout (LDO) linear regulator (maximum
V
IN
= 20 V) is recommended to power the V
DD
rail for maximal
performance. A 4.7 Ω resistor in series with the input capacitor
of the
ADP7118 adds additional rejection at higher frequencies
to reduce any power supply ripple artifacts below the noise floor.
The ADP162 is recommended for powering the V
LOGIC
rail.
TEST POINTS
The evaluation board has various test points for debugging and
monitoring purposes. These test points are described Table 5.
VOLTAGE REFERENCES
The AD5696R provides an internal voltage reference. The
evaluation board provides external references with values of
2.5 V and 5 V. Note that the
ADR3450 requires the use of an
external supply through the EXTSUP connector (see Table 4).
LINK OPTIONS
A number of link options are incorporated on the EVAL-
AD5696RSDZ evaluation board and must be set for the required
operating conditions before using the board. The functions of
these link options are described in Table 4.
Table 3 lists the positions of the different links controlled by the
PC via the USB port. An SDP board operating in single-supply
mode is required.
Table 2. Power Supply Connectors
Connector No. Label External Voltage Supplies Description
EXTSUP, Pin 1 EXTSUP External analog power supply from 2.7 V to 5.5 V, V
DD
.
EXTSUP, Pin 2 Analog ground.
EXTREF, Pin 1 EXTREF External voltage reference, V
LOGIC
.
3.3 V when the evaluation board is controlled through the SDP.
1.8 V to 5.5 V when the evaluation board is controlled through an external connector.
EXTREF, Pin 2 Analog ground.
Table 3. Link Options Setup for SDP Control (Default)
Link Option
PWRSEL 3.3 V
REF Not connected
P1 Not connected
Table 4. Link Functions
Link Description
PWRSEL This link selects the DAC analog voltage source. There are three options as follows:
The 3.3 V option selects the on-board voltage source from the ADP121 .
The USB_SUP option selects the USB supply from Pin 5 of the 120-pin connector of the SDP board.
The EXT_SUP option selects an external supply voltage (EXTSUP connector).
REF This link selects the reference source. There are four options as follows:
The not connected option uses the internal reference of 2.5 V.
The EXT_REF option selects an external reference source (EXTREF connector).
The 2.5 V option selects the on-board reference from the REF192 .
The 5 V option selects the on-board reference from the ADR3450 . This reference requires an external supply.
P1 The P1 link selects the DAC digital voltage source. There are two options as follows:
The connected option shorts V
DD
and V
LOGIC
. Use this option only when the SDP is not connected.
The not connected option opens the connection of V
DD
and V
LOGIC
. Use this option when using the SDP.