EVAL-CONTROLBRD AD [Analog Devices], EVAL-CONTROLBRD Datasheet - Page 23

• Manufacturer Part Number: EVAL-CONTROLBRD
• Description: 16-Bit, 1.33 MSPS PulSAR ADC in MSOP/QFN
• Manufacturer: AD [Analog Devices]

AD7983
APPLICATION HINTS
LAYOUT
AD7983
The printed circuit board (PCB) that houses the AD7983
should be designed so that the analog and digital sections are
separated and confined to certain areas of the board. The pinout of
the AD7983, with all its analog signals on the left side and all its
digital signals on the right side, eases this task.
Avoid running digital lines under the device because these couple
noise onto the die, unless a ground plane under the AD7983 is
used as a shield. Fast switching signals, such as CNV or clocks,
should never run near analog signal paths. Crossover of digital
and analog signals should be avoided.
At least one ground plane should be used. It can be common or
split between the digital and analog section. In the latter case,
Figure 38. Example Layout of the AD7983 (Top Layer)
the planes should be joined underneath the AD7983.
The AD7983 voltage reference input REF has a dynamic input
impedance and should be decoupled with minimal parasitic
inductances. This is done by placing the reference decoupling
ceramic capacitor close to, ideally right up against, the REF and
GND pins and connecting them with wide, low impedance traces.
Finally, the AD7983 power supplies, VDD and VIO, should be
decoupled with ceramic capacitors, typically 100 nF, placed
close to the AD7983 and connected using short and wide traces
to provide low impedance paths and to reduce the effect of
glitches on the power supply lines.
An example of a layout following these rules is shown in
Figure 38 and Figure 39.
EVALUATING THE PERFORMANCE OF THE AD7983
Figure 39. Example Layout of the AD7983 (Bottom Layer)
Other recommended layouts for the AD7983 are outlined
in the documentation of the evaluation board for the AD7983
(EVAL-AD7983CBZ). The evaluation board package includes
a fully assembled and tested evaluation board, documentation,
and software for controlling the board from a PC via the
EVAL-CONTROL BRD.
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