EVAL-AD7719-EB Datasheet, PDF (1/21 Pages) Analog Devices – Evaluation Board for the AD7719, 16&24-Bit, Dual Sigma Delta ADC

a EvaluationBoardfortheAD7719,
16&24-Bit, Dual Sigma Delta ADC
EVAL-AD7719-EB
FEATURES
Full-Featured Evaluation Board for the AD7719
On-Board Reference and Digital Buffers
Various Linking Options
PC Software for Control of AD7719
INTRODUCTION
This Technical Note describes the evaluation board
for the AD7719, Low Voltage, Low Power, 16&24-
Bit, Dual Sigma Delta ADC. The AD7719 is a
complete analog front end for low frequency measure-
ment applications. The AD7719 is factory calibrated
and therefore does not require field calibration. The
device can accept low level input signals directly from
a transducer and produce a serial digital output. It
employs a sigma-delta conversion technique to realize
up to 24 bits (Main ADC) or 16 bits (Auxiliary ADC)
of no missing codes performance. The selected input
signal is applied to a proprietary programmable gain
(Main ADC only) front end based around an analog
modulator. The modulator output is processed by an
on-chip digital filter. The first notch of this digital
filter can be programmed via an on-chip control
register allowing adjustment of the filter cutoff and
output update rate. Full data on the AD7719 is
available in the AD7719 datasheet available from
Analog Devices and should be consulted in conjunc-
tion with this Technical Note when using the evalua-
tion board.
The evaluation board interfaces to the parallel port of an
IBM compatible PC. Software is available with the evalu-
ation board which allows the user to easily program the
AD7719.
Other components on the AD7719 Evaluation Board
include two AD780s (precision 2.5V references), a
32.7680 kHz crystal and digital buffers to buffer
signals to and from the PC.
OPERATING THE AD7719 EVAL BOARD
Power Supplies
This evaluation board has two analog power supply
inputs: AV_DD and AGND. An external +5V must be
applied between these inputs which is used to provide
the V_DD for the AD7719 and the reference. Digital
Power connections are also required through DGND
& DV_DD. The DV_DD is used to provide the DV_DD for
the digital circuitry. DGND and AGND are con-
nected together at the AD7719 GND pin. 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 at the input to
the evaluation board. 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 capacitor as close as
possible to the AD7719 and also at the reference.
Fig. 1. Evaluation Board
Set-up
REV. B
Information furnished by Analog Devices is believed to be accurate
and reliable. However, no responsibility is assumed by Analog
Devices for its use, nor for any infringements of patents or other rights
of third parties which may result from its use. No license is granted
by implication or otherwise under any patent or patent rights of
Analog Devices.
One Technology Way, P.O. Box 9106, Norwood. MA 02062-9106,
U.S.A.
Tel: [phone]
Fax: [phone]