AD5643R Analog Devices, AD5643R Datasheet - Page 27

• Manufacturer Part Number: AD5643R
• Manufacturer: Analog Devices

Specifications of AD5643R

• Resolution (bits): 14bit
• Dac Update Rate: 250kSPS
• Dac Settling Time: 3.5µs
• Max Pos Supply (v): +5.5V
• Single-supply: Yes
• Dac Type: Voltage Out
• Dac Input Format: Ser,SPI

POWER SUPPLY BYPASSING AND GROUNDING
When accuracy is important in a circuit, it is helpful to carefully
consider the power supply and ground return layout on the
board. The printed circuit board containing the AD5663R
should have separate analog and digital sections, each having its
own area of the board.
If the AD5663R 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 AD5663R.
The power supply to the AD5663R should be bypassed with
10 μF and 0.1 μF capacitors. The capacitors should be located as
close as possible to the device, with the 0.1 μF capacitor ideally
right up against the device. The 10 μF capacitors are the
tantalum bead type. It is important that the 0.1 μF capacitor
have low effective series resistance (ESR) and effective series
inductance (ESI), which is found, for example, in common
ceramic types of capacitors.
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This 0.1 μF capacitor provides a low impedance path to ground
for high frequencies caused by transient currents due to internal
logic switching.
The power supply line itself 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 fast switching
digital signals should be shielded from other parts of the board
by 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 through the board. The best 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.
AD5623R/AD5643R/AD5663R