EVAL-ADAS3022EDZ User Guide
UG-484
Rev. A | Page 3 of 32
EVALUATION BOARD HARDWARE
OVERVIEW
The
EVAL-ADAS3022EDZ
evaluation board is designed to
offer a simple evaluation of these revolutionary devices. From
a block diagram perspective, the board uses a set of analog
input test points (or an IDC header), some passive footprints
for RC filtering and external reference, the
ADAS3022
device,
a serial interface to the on-board FPGA, and power that can be
supplied locally or via
EVAL-CED1Z
or externally. Note that
the
ADAS3022
devices also have an on-chip reference; however,
external circuitry is provided for users wanting to test other
suitable options.
The small prototyping area can be useful for building additional
circuitry, if desired. Each block has a specific function as
defined in the following sections.
DEVICE DESCRIPTION
The
ADAS3022
is a complete data acquisition system (DAS)
on a single chip that is capable of converting up to 1 MSPS and
can resolve 8 single-ended inputs or 4 fully differential inputs up
to
±
24.576 V when using ±15 V supplies. It can accept the
commonly used bipolar differential, bipolar single-ended, pseudo
bipolar, or pseudo unipolar input signals as shown in Table 1 thus
allowing the use of almost any direct sensor interface.
The
ADAS3022
is an ideal replacement for a typical 16-bit
1 MSPS precision data acquisition system that simplifies the
design challenges by eliminating signal buffering, level shifting,
amplification/attenuation, common-mode rejection, settling
time, or any of the other analog signal conditioning challenges
while allowing smaller form factor, faster time to market, and
lower costs.
Data communication to and from the
ADAS3022
occurs
asynchronously without any pipeline delay using a common
4-wire serial interface compatible with SPI, FPGA, and DSP.
A rising edge on CNV samples the differential analog inputs of
a channel or channel pair. The
ADAS3022
configuration register
allows the user to configure the number of enabled channels, the
differential input voltage range, and the interface mode using the
evaluation board and software as detailed in this user guide.
Complete specifications for the
ADAS3022
are provided in the
product data sheet and should be consulted in conjunction with
this user guide when using the evaluation board. Full details on
the
EVAL-CED1Z
are available on the Analog Devices website.
Table 1. Typical Input Range Selection
Signals
Input Range, V
IN
(V)
Differential
±1 V
±1.28 V
±2.5 V
±2.56 V
±5 V
±10.24 V
±10 V
±20.48 V
Single Ended
1
0 V to 1 V
±0.64 V
0 V to 2.5 V
±1.28 V
0 V to 5 V
±2.56 V
0 V to 10 V
±5.12 V
1
V
CM
adjusted to half the maximum input voltage.
JUMPERS, SOLDER PADS, AND TEST POINTS
Numerous solder pads and test points are provided on the
evaluation board and are detailed fully in Table 4, Table 5,
and Table 6. Note the nomenclature for this evaluation board
for a signal that is also connected to an IDC connector would
be signal_I. The two 3-pin user selectable jumpers are used for
the ADCs reference selection and are fully described in the
Reference section.
ANALOG INTERFACE
The analog interface is provided with test points for each of the
analog inputs IN[7:0] and COM (that is, IN0_I is common to
both the test point and to P1). The passive device footprints
can be used for filtering, if desired. A simple RC filter made up
of 22 Ω and 2700 pF NPO capacitors is provided. Note that
the use of stable dielectric capacitors, such as NPO or COG, is
required in the analog signal path to preserve the
ADAS3022
distortion. Using X5R or other capacitors in the analog signal
path greatly reduces the performance of the system. Also, note
that many bench top arbitrary waveform generators (AWGs)
use 12-bit or 14-bit digital-to-analog converter outputs such
that the 16-bit
ADAS3022
devices digitize this directly resulting
in erroneous looking data. If such an AWG is used, a high-order
band-pass filter should be used to filter the unwanted noise
from these sources.
The
ADAS3022
COM input can be routed to P1 or GND using
P31. Set the jumper across Pin 1 and Pin 2 to route to P1. Set
the jumper across Pin 2 to Pin 3 to GND COM. This is useful
for single-ended applications.
For dynamic performance, an FFT test can be done by applying
a very low distortion ac source, such as an Audio Precision
System 2702. This source can be set for balanced or unbalanced,
and can be floated or grounded depending on the user’s choice.
