AD9779 Analog Devices, AD9779 Datasheet - Page 46

• Manufacturer Part Number: AD9779
• Description: Dual 16-Bit, 1 GSPS, Digital-to-Analog Converter
• Manufacturer: Analog Devices

Specifications of AD9779

• Resolution (bits): 16bit
• Dac Update Rate: 1GSPS
• Dac Settling Time: n/a
• Max Pos Supply (v): +3.47V
• Single-supply: Yes
• Dac Type: Current Out
• Dac Input Format: Par

AD9776/AD9778/AD9779
EVALUATION BOARD OPERATION
The AD977x evaluation board is designed to optimize the DAC
performance and the speed of the digital interface, yet remains
user friendly. To operate the board, the user needs a power
source, a clock source, and a digital data source. The user also
needs a spectrum analyzer or an oscilloscope to look at the DAC
output. The diagram in Figure 100 illustrates the test setup. A
sine or square wave clock works well as a clock source. The dc
offset on the clock is not a problem, since the clock is ac-coupled
on the evaluation board before the REFCLK inputs. All
necessary connections to the evaluation board are shown in
more detail in Figure 101.
CLOCK IN
GENERATOR
PATTERN
DIGITAL
P4 Digital Input Connector
DATACLK OUT
Figure 101. AD977x Evaluation Board Showing All Connections
ADAPTER
AUX33
CABLES
S7 DCLKOUT
GENERATOR
DVDD18
CLOCK
Figure 100. Typical Test Setup
CLKIN
Rev. A | Page 46 of 56
AD9779
EVALUATION
SPI PORT
AD9779
DVDD33
BOARD
SPI PORT
J1 CLOCK IN
JP15
JP14
JP16
JP17
JP4
JP8
JP3
JP2
CVDD18
The evaluation board comes with software that allows the user
to program the SPI port. Via the SPI port, the devices can be
programmed into any of its various operating modes. When
first operating the evaluation board, it is useful to start with a
simple configuration, that is, a configuration in which the SPI
port settings are as close as possible to the default settings. The
default software window is shown in Figure 102. The arrows
indicate which settings need to be changed for an easy first time
evaluation. Note that this implies that the PLL is not being used
and that the clock being used is at the speed of the DAC output
sample rate. For a more detailed description of how to use the
PLL, see the PLL Loop Filter Bandwidth section.
S5 OUTPUT 1
S6 OUTPUT 2
AVDD33
AD8349
1.8V POWER SUPPLY
3.3V POWER SUPPLY
MODULATOR
AD9779/8/6
SPECTRUM
ANALYZER
ANALOG
DEVICES
LOCAL OSC
OUTPUT
REV D
5V Supply
INPUT
J2
+5V
GND