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ADS8406

SLAS426A – AUGUST 2004 – REVISED DECEMBER 2004

As with the AGND connections, +VA should be connected to a 5-V power supply plane or trace that is separate

from the connection for digital logic until they are connected at the power entry point. Power to the ADS8406

should be clean and well bypassed. A 0.1-µF ceramic bypass capacitor should be placed as close to the device

as possible. See Table 2 for the placement of the capacitor. In addition, a 1-µF to 10-µF capacitor is

recommended. In some situations, additional bypassing may be required, such as a 100-µF electrolytic capacitor

or even a Pi filter made up of inductors and capacitors—all designed to essentially low-pass filter the 5-V supply,

removing the high frequency noise.

Table 2. Power Supply Decoupling Capacitor Placement

POWER SUPPLY PLANE

CONVERTER ANALOG SIDE

CONVERTER DIGITAL SIDE

SUPPLY PINS

(4,5), (8,9), (10,11), (13,15),

Pin pairs that require shortest path to decoupling capacitors

(24,25), (34, 35)

(43,44), (45,46)

Pins that require no decoupling

12, 14

37

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