ADUCM320 Datasheet, PDF (29/31 Pages) Analog Devices – Fully differential and single-ended modes

ADuCM320
Data Sheet
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.
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.
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.
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.
Rev. C | Page 28 of 30