AD5415YRU-REEL AD [Analog Devices], AD5415YRU-REEL Datasheet - Page 24

• Manufacturer Part Number: AD5415YRU-REEL
• Description: Dual 12-Bit, High Bandwidth, Multiplying DAC with 4-Quadrant Resistors and Serial Interface
• Manufacturer: AD [Analog Devices]

AD5415
PCB LAYOUT AND POWER SUPPLY DECOUPLING
In any circuit where accuracy is important, careful considera-
tion of the power supply and ground return layout helps to
ensure the rated performance. The printed circuit board on
which the AD5415 is mounted should be designed so that the
analog and digital sections are separated, and confined to
certain areas of the board. If the DAC is in a system where
multiple devices require an AGND-to-DGND connection, the
connection should be made at one point only. The star ground
point should be established as close as possible to the device.
The DAC should have ample supply bypassing of 10 µF in
parallel with 0.1 µF on the supply located as close to the package
as possible, ideally right up against the device. The 0.1 µF
capacitor should have low effective series resistance (ESR) and
effective series inductance (ESI), like the common ceramic types
that provide a low impedance path to ground at high
frequencies, to handle transient currents due to internal logic
switching. Low ESR 1 µF to 10 µF tantalum or electrolytic
capacitors should also be applied at the supplies to minimize
transient disturbance and filter out low frequency ripple.
Fast switching signals such as clocks should be shielded with
digital ground to avoid radiating noise to other parts of the
board, and should never be run near the reference inputs.
Avoid crossover of digital and analog signals. Traces on opposite
sides of the board should run at right angles to each other. This
reduces the effects of feedthrough on the board. A microstrip
technique is by far the best, but not always possible with a
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double-sided board. In this technique, the component side of
the board is dedicated to the ground plane while signal traces
are placed on the soldered side.
It is good practice to employ compact, minimum lead length
PCB layout design. Leads to the input should be as short as
possible to minimize IR drops and stray inductance.
The PCB metal traces between V
matched to minimize gain error. To maximize on high fre-
quency performance, the I-to-V amplifier should be located
as close to the device as possible.
EVALUATION BOARD FOR THE DAC
The evaluation board consists of an AD5415 DAC and a
current-to-voltage amplifier, AD8065. Included on the
evaluation board is a 10 V reference, ADR01. An external
reference can also be applied via an SMB input.
The evaluation kit consists of a CD-ROM with self-installing
PC software to control the DAC. The software allows the user to
write a code to the device.
POWER SUPPLIES FOR THE EVALUATION BOARD
The board requires ±12 V and +5 V supplies. The +12 V V
and V
used to power the DAC (V
Both supplies are decoupled to their respective ground plane
with 10 µF tantalum and 0.1 µF ceramic capacitors.
SS
are used to power the output amplifier, while the +5 V is
DD1
) and transceivers (V
REF
and R
FB
should also be
CC
).
DD