EVAL-AD5445EBZ Analog Devices Inc, EVAL-AD5445EBZ Datasheet - Page 23

• Manufacturer Part Number: EVAL-AD5445EBZ
• Description: BOARD EVALUATION FOR AD5445
• Manufacturer: Analog Devices Inc

Specifications of EVAL-AD5445EBZ

• Number Of Dac's: 1
• Number Of Bits: 12
• Outputs And Type: 2, Single Ended
• Sampling Rate (per Second): 20M
• Data Interface: Parallel
• Settling Time: 30ns
• Dac Type: Current
• Voltage Supply Source: Single
• Operating Temperature: -40°C ~ 125°C
• Utilized Ic / Part: AD5445
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

PCB LAYOUT AND POWER SUPPLY DECOUPLING
In any circuit where accuracy is important, careful consider-
ation of the power supply and ground return layout helps to
ensure the rated performance. The printed circuit board on
which the AD5424/AD5433/AD5445 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.
These DACs 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 and 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 through the
board. A micro-strip technique is by far the best, but not always
possible with a 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 solder side.
Rev. B | Page 23 of 32
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 high frequency
performance, the I-to-V amplifier should be located as close to
the device as possible.
EVALUATION BOARD FOR THE
AD5424/AD5433/AD5445
The board consists of a 12-bit AD5445 and a current-to-voltage
amplifier, the AD8065. Included on the evaluation board is a
10 V reference, the ADR01. An external reference may 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
simply write a code to the device.
POWER SUPPLIES FOR EVALUATION BOARD
The board requires ±12 V and 5 V supplies. The 12 V V
and V
+5 V V
transceivers (V
Both supplies are decoupled to their respective ground plane
with 10 μF tantalum and 0.1 μF ceramic capacitors.
Link1 (LK1) is provided to allow selection between the on-
board reference (ADR01) and an external reference applied
through J2.
SS
DD
are used to power the output amplifier, while the
and V
CC
SS
).
are used to power the DAC (V
AD5424/AD5433/AD5445
REF
and R
FB
should also be
DD1
) and
DD