AD5045 datasheet(24/28 Pages) AD

24 / 28 page

AD5024/AD5044/AD5064

Data Sheet

Rev. F | Page 24 of 28

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 (PCB) containing the AD5024/AD5044/

AD5064/AD5064-1 should have separate analog and digital

sections. If the AD5024/AD5044/AD5064/AD5064-1 are 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

AD5024/AD5044/AD5064/AD5064-1.

The power supply to the AD5024/AD5044/AD5064/AD5064-1

should be bypassed with 10 µF and 0.1 µF capacitors. The capaci-

tors should be as physically 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

low effective series inductance (ESI), such as is typical of common

ceramic types of capacitors. 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 should have as large a trace as possible to

provide a low impedance path and 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 tech-

nique, 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.

AD5045 Datasheet(PDF) 24 Page - Analog Devices