AD9683-250EBZ Analog Devices, AD9683-250EBZ Datasheet - Page 43

• Manufacturer Part Number: AD9683-250EBZ
• Description: Data Conversion IC Development Tools
• Manufacturer: Analog Devices
• Type: ADCr
• Series: AD9683r

Specifications of AD9683-250EBZ

• Rohs: yes
• Product: Evaluation Boards
• Tool Is For Evaluation Of: AD9683-250
• Interface Type: SPI
• Operating Supply Voltage: 1.8 V
• Description/function: Evaluation board with AD9683-250
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Operating Supply Current: 149 mA
• For Use With: AD9683-250

Data Sheet
APPLICATIONS INFORMATION
DESIGN GUIDELINES
Before starting system level design and layout of the AD9683, it
is recommended that the designer become familiar with these
guidelines, which describe the special circuit connections and
layout requirements needed for certain pins.
Power and Ground Recommendations
When connecting power to the AD9683, it is recommended that
two separate 1.8 V power supplies be used. The power supply for
AVDD can be isolated, and the power supply for DVDD and
DRVDD can be tied together, in which case, an isolation inductor
of approximately 1 µH is recommended. Alternativly, the
JESD204B PHY power (DRVDD) and analog (AVDD) supplies
can be tied together, and a separate supply can be used for the
digital outputs (DVDD).
The designer can employ several different decoupling capacitors
to cover both high and low frequencies. Place these capacitors
close to the point of entry at the PCB level and close to the pins
of the part with minimal trace length.
When using the AD9683, a single PCB ground plane is sufficient.
With proper decoupling and smart partitioning of the PCB analog,
digital, and clock sections, optimum performance is easily
achieved.
Exposed Pad Thermal Heat Slug Recommendations
It is mandatory that the exposed pad on the underside of the
ADC be connected to analog ground (AGND) to achieve the
best electrical and thermal performance. Mate a continuous,
exposed (no solder mask) copper plane on the PCB to the
AD9683
exposed pad.
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The copper plane should have several vias to achieve the lowest
possible resistive thermal path for heat dissipation to flow through
the bottom of the PCB. Fill or plug these with nonconductive
epoxy.
To maximize the coverage and adhesion between the ADC and
the PCB, overlay a silkscreen to partition the continuous plane
on the PCB into several uniform sections. This provides several tie
points between the ADC and the PCB during the reflow process.
Using one continuous plane with no partitions guarantees only
one tie point between the ADC and the PCB. See the evaluation
board for a PCB layout example. For detailed information about
the packaging and PCB layout of chip scale packages, refer to
the
Guide for the Lead Frame Chip Scale Package (LFCSP).
VCM
Decouple the VCM pin to ground with 0.1 µF capacitors, as shown
in Figure 45. It is recommended to place one 0.1 µF capacitor as
close as possible to the VCM pin and another at the VCM
connection to the analog input network.
SPI Port
Do not activate the SPI port during periods when the full dynamic
performance of the converter is required. Because the SCLK, CS ,
and SDIO signals are typically asynchronous to the ADC clock,
noise from these signals can degrade converter performance. If the
on-board SPI bus is used for other devices, it may be necessary
to provide buffers between this bus and the
these signals from transitioning at the converter input pins during
critical sampling periods.
AN-772
Application Note, A Design and Manufacturing
AD9683
AD9683
to keep