EVAL-AD7891-2CB Datasheet, PDF (1/12 Pages) Analog Devices – Evaluation Board for Single Supply, 12-Bit 500 kSPS ADC

a
Evaluation Board for Single Supply,
12-Bit 500 kSPS ADC
EVAL-AD7891-2CB
FEATURES
Full-Featured Evaluation Board for the AD7891-2
EVAL-CONTROL BOARD Compatible
Stand Alone Capability
Interfacing to this board is through a 9-way D-type connector
and a 96-way connector. This 96-way connector is compatible
with the EVAL-CONTROL BOARD which is also available
from Analog Devices. External sockets are provided for the
conversion start input, analog inputs and an external reference
input option.
On-Board Analog Buffering and Reference
Various Linking Options
OPERATING THE AD7891-2 EVALUATION BOARD
Power Supplies
PC Software for Control and Data Analysis when used
This evaluation board has four analog power supply inputs:
with EVAL-CONTROL BOARD
V_DD, DGND, +12 V and -12 V. The VDD supply is nominally
+5 V and is used to power the AD7891-2 and the on-board
INTRODUCTION
digital integrated circuits. The +12 V and -12 V supplies are
This Application Note describes the evaluation board for the
used to power the AD713 quad op-amps and the AD780 voltage
AD7891-2 12-Bit A/D converter. The AD7891-2 is an eight
reference and the reference buffer. The DGND connection is to
channel data acquisition system that operates from a single +5 V _{the digital ground plane. This DGND ground plane connects to}
supply and accepts input signals in the ranges 0 to +5 V , 0 to
the AGND ground plane at the AD7891-2. Therefore, it is
+2.5 V or ± 2.5 V. It incorporates an input multiplexer, an on
recommended not to connect AGND and DGND elsewhere in
chip track/hold amplifier, an internal +2.5 V reference and on-
the system. The various analog and digital supplies are provided
chip versatile interface structures that allow both serial and
through the power-supply terminals on the board. When using
parallel connection to a microprocessor. This flexible serial
the AD7891-2 evaluation board with the EVAL-CONTROL
interface allows the AD7891-2 to connect directly to Digital
BOARD, all supplies are provided by the EVAL-CONTROL
Signal Processors (ADSP-2101, DSP56001, etc.) and Micro-
BOARD.
controllers (8XC51, 68HC11, etc.). Full data on the AD7891-
2 is available in the AD7891 data sheet available from Analog
Devices and should be consulted in conjunction with this
Application Note when using the Evaluation Board.
On-board components include an AD780 which is a pin
All supplies are decoupled to ground with 10µF tantalum and
0.1µF ceramic disc capacitors. The +12 V and -12 V supplies
for the amplifiers are decoupled to the AGND plane while the
AV_DD supply for the AD7891 is decoupled to the AGND plane
through a 10 µF capacitor and to the DGND plane through a
programmable +2.5 V or +3V ultra high precision bandgap
0.1 µF capacitor.
reference, a buffer amplifier to buffer the reference when using
inputs in the ± 2.5 V range and two AD713 quad op-amps to
buffer the analog inputs.
FUNCTIONAL BLOCK DIAGRAM
AIN 8
Conversion
Start Input
9-Way
D-Type
Connector
Analog
Inputs
Range
Selection
Jumpers
AD7891-2 ¹²
ADC
AD7891-1
Evaluation
Board
AIN 1
Reference
Input
(+2.5 V)
AD780
Reference
REV. A
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use, nor for any infringements of patents or other rights of third parties
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