Datasheet

EVAL-AD7294
Rev. 0 | Page 19 of 24
INES
GROUNDING
When accuracy is important in a circuit, carefully consider the
power supply and ground return layout on the board. The
printed circuit board containing the AD7294 should have
separate analog and digital sections, each having its own area of
the board. If the AD7294 is in a system where other devices
require an AGND-to-DGND connection, the connection
should be made at one point only. This ground point should be
as close as possible to the AD7294.
The power supply to the AD7294 should be decoupled with
10 µF tantalum and 0.1 µF ceramic capacitors. The capacitors
should be placed as close as possible to the device, with the
0.1 µF ceramic capacitor closer to the device than the tantalum
capacitor. In additi 1 µF capacitor
impedance path to ground for high frequencies caused by
transient currents due to internal logic switching.
The power supply line should have as large a trace as possible to
provide a low impedance path and to reduce glitch effects on the
supply line. Clocks and other components with fast-switching
digital signals should be shielded from other parts of the board
by a digital ground. Avoid crossover of digital and analog signals if
possible. When traces cross on opposite sides of the board, ensure
that they run at right angles to each other to reduce feedthrough
effects on the board. The most efficient board layout technique
is the microstrip technique, where the component side of the board
is dedicated to the ground plane only and the signal traces are
placed on the solder side; however, this is not always possible
with a 2-layer board.
LAYOUT AND CONFIGURATION GUIDEL
POWER SUPPLY DECOUPLING AND
on, it is important that the 0.
have low effective series resistance (ESR) and low effective
series inductance (ESI). The 0.1 µF capacitor provides a low