EVAL-AD7714-3EB Datasheet, PDF (1/8 Pages) Analog Devices – Evaluation Board for Signal Conditioning ADC

a
Evaluation Board for
Signal Conditioning ADC
EVAL-AD7714-3EB
FEATURES
Operates from a Single +3V Supply
On-Board Reference and Digital Buffers
Various Linking Options
Direct Hook-Up to Printer Port of PC
PC Software for Control and Data Analysis
INTRODUCTION
This Application Note describes the evaluation board for the
AD7714-3, 24-Bit signal conditioning ADC. The AD7714 is a
complete analog front end for low-frequency applications
providing either three fully-differential or five pseudo-
differential input channels. The device accepts low-level signals
directly from a transducer and outputs a serial digital word. It
employs a sigma delta technique to realize up to 24 bits of no
missing codes performance. Full data on the AD7714-3 is
available in the AD7714 data sheet available from Analog
Devices and should be consulted in conjunction with this
Application Note when using the Evaluation Board.
Included on the evaluation board, along with the AD7714-3, are
an AD589, a +1.23 V precision bandgap reference, a
2.4576MHz crystal and digital buffers to buffer signals to and
from the edge connectors.
Interfacing to this board is provided either through a 36-Way
Centronics Connector or through a 9-way D-type connector.
External sockets are provided for the analog inputs, an external
reference input option and an external master clock option.
OPERATING THE AD7714-3 EVALUATION BOARD
Power Supplies
The evaluation board has four power supply input pins: AV_DD,
AGND, DV_DD and DGND. The AD7714-3 is specified with an
AV_DD of +3V. Therefore, the AV_DD voltage supplied to the
board must be +3V. This AV_DD voltage is also used to power the
AD589 reference. To correctly handle the interface signals the
board must be operated from a +3V DV_DD voltage also. When
using the 36-way Centronics connector to interface the printer
port of a PC to the board, the signals at this edge connector are
5V signals. The 74FCT3244T translates these signals to 3V
signals for the rest of the logic on the evaluation board. To run
the board from a single +3V supply, simply connect the AV_DD
and DV_DD inputs together.
Both AGND and DGND inputs are provided on the board.
AGND connects to the AD7714-3 AGND pin and also con-
nects to the GND pin of the AD589. DGND connects to the
DGND pin of the AD7714 and to the GND of the digital chips
on the board. The AGND and DGND planes are connected at
the AD7714. Therefore, it is recommended not to connect
AGND and DGND elsewhere in the system to avoid ground
loop problems. When using a single supply for both AV_DD and
DV_DD, only one ground connection should be made to the
board. This connection should be made to the board's AGND
input terminal.
Both supplies are decoupled to their respective ground plane
with 10µF tantalum and 0.1µF ceramic disc capacitors.
FUNCTIONAL BLOCK DIAGRAM
AVDD AGND DVDD DGND
9-WAY D-TYPE CONNECTOR
AIN1
AIN2
AIN3
AIN4
AIN5
AIN6
AD7714
ADC
BUFFERS
36-WAY
CENTRONICS
CONNECTOR
AD589
REFERENCE
REF IN
MCLK IN
REV. A
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]