AD5522JSVD AD [Analog Devices], AD5522JSVD Datasheet - Page 44

• Manufacturer Part Number: AD5522JSVD
• Description: Quad Parametric Measurement Unit With Integrated 16-Bit Level Setting DACs
• Manufacturer: AD [Analog Devices]

AD5522
Preliminary Technical Data
POWER SUPPLY DECOUPLING
In any circuit where accuracy is important, careful
consideration of the power supply and ground return layout
helps to ensure the rated performance. The printed circuit
board on which the AD5522 is mounted should be designed so
that the analog and digital sections are separated and confined
to certain areas of the board. If the AD5522 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.
For supplies with multiple pins (AV
, AV
, V
), it is
SS
DD
CC
recommended to tie these pins together and to decouple each
supply once.
The AD5522 should have ample supply decoupling of 10 µF in
parallel with 0.1 µF on each supply located as close to the
package as possible, ideally right up against the device. The
10µF capacitors are the tantalum bead type. The 0.1 µF
capacitor should have low effective series resistance (ESR) and
effective series inductance (ESI), such as the common ceramic
types that provide a low impedance path to ground at high
frequencies, to handle transient currents due to internal logic
switching.
Digital lines running under the device should be avoided,
because these couple noise onto the device. The analog ground
plane should be allowed to run under the AD5522 to avoid
noise coupling (only with the package with paddle up).. The
power supply lines of the AD5522 should use as large a trace as
possible to provide low impedance paths and reduce the effects
of glitches on the power supply line. Fast switching digital
signals 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. It is essential to minimize noise
lines. Avoid crossover of digital and analog signals.
on all V
REF
Traces on opposite sides of the board should run at right angles
to each other. This reduces the effects of feedthrough through
the board. As is the case for all thin packages, care must be
taken to avoid flexing the package and to avoid a point load on
the surface of this package during the assembly process.
Also note that the exposed paddle of the AD5522 is connected
to the negative supply AV
.
SS
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