Data Sheet ADuCM322
Rev. 0 | Page 21 of 23
APPLICATIONS INFORMATION
RECOMMENDED CIRCUIT AND COMPONENT
VALUES
Figure 13 shows a typical connection diagram for the
ADuCM322.
Supplies and regulators must be adequately decoupled
with capacitors connected between the AVDDx, DVDD_x,
AVDD_REGx, IOVDDx, and VDD1 balls and their associated
GND balls (AGNDx, IOGNDx, and DGNDx). Table 10
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
ground balls (IOGNDx and AGND1, respectively). In addition,
place a 10 μF capacitor conveniently near to these balls.
Similarly, the analog supply balls, 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 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 ADuCM322 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. The AVDD_REG1 output ball must be connected to
Ball A3, Ball A4, Ball A8, and Ball A9.
Connect the IREF ball to DGND via a standard 3.3 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.
