Datasheet

UG-290 Evaluation Board User Guide
Rev. 0 | Page 4 of 28
WALL OUTLE
T
100V TO 240V AC
47Hz TO 63Hz
09910-002
SIGNAL
SYNTHESIZER
SWITCHING
POWER
SUPPLY
SWITCHING
POWER
SUPPLY
ANALOG INPUT
6V DC
2A MAX
6V DC
2A MAX
SIGNAL
SYNTHESIZER
ENCODE
PC RUNNING
VISUAL ANALOG
USER SOFTWARE
Figure 2. Evaluation Board Connection
09910-003
AD9434/
AD9484
0.1µ
F
0.1µF
VIN+
VIN–
0.1µF
33Ω
33Ω
33Ω
33Ω
1.5V p-p
0.1µF
5pF
0Ω
VCM
Figure 3. Default Analog Input Configuration of the AD9434 and AD9484
DEFAULT OPERATION AND JUMPER SELECTION
SETTINGS
This section explains the default and optional settings or modes
allowed on the AD9434 and AD9484 evaluation board.
Power Circuitry
Connect the switching power supply that is supplied in the
evaluation kit between a rated 100 V to 240 V ac wall outlet (at
47 Hz to 63 Hz) and J300.
Analog Input
The input on the evaluation board is set up for a double balun-
coupled analog input with a 50 Ω impedance (see Figure 3). The
analog input to the AD9434 and AD9484 is a differential buffer.
For best dynamic performance, source impedances driving
VIN+ and VIN− are matched such that common-mode settling
errors are symmetrical. The analog input is optimized to provide
superior wideband performance and requires that the analog
inputs be driven differentially. SNR and SINAD performance
degrades significantly if the analog input is driven with a single-
ended signal.
The analog inputs are self-biased by an on-chip reference to
provide a common-mode voltage level of nominally 1.7 V.
An internal differential voltage reference creates positive and
negative reference voltages that define the 1.5 V p-p fixed span
of the ADC core. This internal voltage reference can be adjusted
by means of an SPI control.
VREF
The AD9434 VREF pin (Pin 31) allows the user to monitor the
on-board voltage reference or provide an external reference
(requires configuration through the SPI). The three optional
settings are internal V
REF
(the pin is connected to 20 kΩ to
ground), export V
REF
, and import V
REF
. See the settings for
Register 0x18 in Table 1.