ADUCM320BBCZ datasheet(29/31 Pages) AD

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ADuCM320

Data Sheet

Rev. C | Page 28 of 30

RECOMMENDED CIRCUIT AND COMPONENT VALUES

Figure 15 shows a typical connection diagram for the ADuCM320.

Supplies and regulators must be adequately decoupled with

capacitors connected between the AVDDx, PVDDx, DVDD_x,

AVDD_REGx, IOVDDx, and VDD1 balls and their associated

GND balls (AGNDx, PGND, IOGNDx, and DGNDx). Table 11

indicates which ground balls are paired with which supply balls.

There are four digital supply balls, IOVDD1, IOVDD2, IOVDD3,

and VDD1. Decouple these balls with a 100 nF capacitor placed

as near as possible to each of the four balls and their associated

GND balls (IOGNDx and AGND1, respectively). In addition,

place a 10 μF capacitor conveniently near to these balls.

Similarly, the analog supply pins, AVDD3 and AVDD4, each

require a 100 nF capacitor placed as near as possible to each ball

and its associated AGNDx ball, and place a 10 μF capacitor

conveniently near to these balls.

The IDACs source their output currents from the PVDDx

supply balls. Each PVDDx supply ball must have a 100 nF

capacitor near to each ball and their associated GND balls

(PGND). In addition, place at least one 10 μF capacitor at the

source of the PVDDx supply.

The IDAC output filters depend on a 10 nF capacitor being

placed between the CDAMPx and PVDDx.

The ADC reference requires a 4.7 μF capacitor placed between

ADC_REFP and ADC_REFN and located as near as possible to

each ball. ADC_REFN must be connected directly to AGND4.

The ADuCM320 contains four internal regulators. These

regulators require external decoupling capacitors. The

DVDD_1V8 and DVDD_2V5 balls each require a 470 nF

capacitor to DGND1 and IOGND3, respectively. AVDD_REG0

and AVDD_REG1 each require a decoupling capacitor to

AGND4.

To generate an accurate and low drift reference current, connect

the IREF ball to AGND4 via a low ppm 3.16 kΩ resistor.

Take care in the layout to ensure that currents flowing from the

ground end of each decoupling capacitor to its associated

ground ball share as little track as possible with other ground

currents on the printed circuit board.

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