Datasheet

Evaluation Board User Guide UG-155
Rev. 0 | Page 3 of 12
EVALUATION BOARD HARDWARE
POWER SUPPLIES
To power the AD5668 evaluation board, supply 5.5 V between
the AVDD and AGND inputs for the analog supply, and supply
5 V between DVDD and DGND inputs for the digital supply.
Both AGND and DGND inputs are provided on the board. The
AGND and DGND planes are connected at one location close
to the AD5668. It is recommended not to connect AGND and
DGND elsewhere in the system to avoid ground loop problems.
All supplies are decoupled to ground with 10 μF tantalum and
0.1 μF ceramic capacitors.
Table 1. Power Supply Connectors
Connector No. Voltage
J1
Analog positive supply and ground, AVDD and
AGND.
For single-supply operation, supply 5.5 V.
J2
Digital positive power supply, DVDD.
For single-supply operation, supply 5 V.
LINK OPTIONS
A number of link and switch options are incorporated in the
evaluation board and should be set for the required operating
setup before using the board. Table 2 describes the positions of
the different links to control the evaluation board by the PC, via
the USB port, using the AD5668 in single-supply mode. The
functions of these link options are described in detail in Tabl e 3 .
Table 2. Link Options Setup for SDP Control (Default)
Link No. Options
LK1 A
LK2 to LK3 Inserted
LK4 Inserted
LK5 B
LK6 A
LK7 A
LK8 A
LK9 to LK14 Inserted
Table 3. Link Functions
Link No. Option
LK1 This link selects the AVDD power supply source for the analog circuitry:`
Position A selects J1 as the AVDD analog circuitry power supply source.
Position B selects the DVDD source as the AVDD analog circuitry power supply source (see LK6).
LK2
This link connects the V
OUT
G pin of the AD5668 to the input pin of the ADG738 demultiplexer, so that DAC output value can be
monitored using the on-board AD7476 ADC.
LK3
This link connects the V
OUT
H pin of the AD5668 to the input pin of the ADG738 demultiplexer, so that DAC output value can be
monitored using the on-board AD7476 ADC.
LK4
This link connects a 0.1 F capacitor to AGND on the V
REFIN/VREFOUT pin. It is recommended to connect this when using the
internal reference.
LK5 This link selects the reference source:
Position A selects the internal reference as the reference source. The part must be written to via software to turn on the internal
reference.
Position B selects the on-board 5 V reference as the reference source.
LK6 This link selects the 5 V power supply source for the digital circuitry:
Position A selects V_IO as the 5 V digital circuitry power supply source.
Position B selects J2 as the 5 V digital circuitry power supply source.
LK7 This link selects the DAC voltage source:
Position A selects the AVDD analog circuitry power supply source.
Position B selects the on-board 5 V reference as the power supply source.
LK8
This link sets the RESET
pin on the ADG738:
Position A allows normal operation of the switch.
Position B resets the switch.
LK9 to
LK14
This link connects the VOUTA to VOUTF pins of the AD5668 to the input pins of ADG738 demultiplexer, so that the DAC output
value can be monitored using the on-board AD7476 ADC.