EVAL-AD7707EB Datasheet, PDF (1/16 Pages) Analog Devices – Evaluation Board for the AD7707 3V/5V, +/-10V Input Range, 1mW, 3Channel, 16-Bit, Sigma Delta ADC

a EvaluationBoardfortheAD77073V/5V,+/-10VInput
Range, 1mW, 3Channel, 16-Bit, Sigma Delta ADC
EVAL-AD7707EB
FEATURES
Full-Featured Evaluation Board for the AD7707
On-Board Reference and Digital Buffers
Various Linking Options
PC Software for Control of AD7707
On-Board Patchwork Area
INTRODUCTION
This Technical Note describes the evaluation board for the
AD7707, 3V/5V, +/-10V Input Range, 1mW, 3 Channel, 16-
Bit, Sigma Delta ADC. The AD7707 is a complete analog
front end for low frequency measurement applications. This
three-channel device can accept either low level input signals
directly from a transducer or high level (± 4 x VBIAS) signals
and produce a serial digital output. The AD7707 operates
from a single 2.7V to 3.3V or 4.75V to 5.25V supply. The
AD7707 features two low level pseudo-differential analog
input channels, one high level input channel and a differential
reference input. Full data on the AD7707 is available in the
AD7707 datasheet available from Analog Devices and should
be consulted in conjunction with this Technical Note when
using the evaluation board.
The evaluation board interfaces to the parallel port of an IBM
compatible PC. Software is available with the evaluation
board which allows the user to easily program the AD7707.
Other components on the AD7707 Evaluation Board include
an AD780 (a precision 2.5V reference), an AD589 (a 1.23V
precision bandgap reference), a 4.9152 MHz crystal and
digital buffers to buffer signals to and from the PC.
OPERATING THE AD7707 EVAL BOARD
Power Supplies
This evaluation board has two analog power supply inputs:
AV_DD and AGND. An external +5V or +3V must be applied
between these inputs which is used to provide the AV_DD for the
AD7707 and the reference. DGND and DV_DD connections
are also available. The DV_DD is used to provide the DV_DD for
the AD7707 DV_DD pin and the digital circuitry. When AV_DD
is set to +5V, DV_DD can be +3V or +5V. When AV_DD is set
to +3V, DV_DD can only be +3V. DV_DD should never exceed
AV_DD. DGND and AGND are connected together under the
AD7707. Therefore, it is recommended not to connect
AGND and DGND elsewhere in the system.
All power supplies are decoupled to their respective grounds.
DV_DD is decoupled using a 10µF tantalum capacitor and
0.1µF ceramic capacitor as close as possible to the AD7707
DV_DD pin. It is again decoupled using 0.1µF capacitors as
close as possible to each logic device. AV_DD is decoupled
using a 10µF tantalum capacitor and 0.1µF ceramic capaci-
tor as close as possible to the AD7707 and also at the
reference.
DVDD
Figure 1: Evaluation Board Setup
VREF- VREF+
DGND AGND
AVDD
AD1580
REFERENCE
36-W AY
C E N T R O N IC S
CONNECTOR
BUFFERS
AD7707
ADC
AG ND
AD780
REFERENCE
9-W AY D-TYPE CONNECTOR
CRYSTAL
M CLK IN
AIN1 LCOM AIN2 AIN3 HCOM HBIAS
REV. A
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use, nor for any infringements of patents or other rights of third parties
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