EVAL-AD7891-1CB Datasheet, PDF (1/12 Pages) Analog Devices – Evaluation Board for Single Supply, 12-Bit 454 kSPS ADC

a
Evaluation Board for Single Supply,
12-Bit 454 kSPS ADC
EVAL-AD7891-1CB
FEATURES
Full-Featured Evaluation Board for the AD7891-1
EVAL-CONTROL BOARD Compatible
Stand Alone Capability
On-Board Analog Buffering and Reference
Various Linking Options
PC Software for Control and Data Analysis when used
with EVAL-CONTROL BOARD
INTRODUCTION
This Application Note describes the evaluation board for the
AD7891-1 12-Bit A/D converter. The AD7891 is an eight
channel data acquisition system that operates from a single +5 V
supply and accepts input signals in the range ±5 V or ± 10 V. It
incorporates an input multiplexer, an on chip track/hold
amplifier, an internal +2.5 V reference and on-chip versatile
interface structures that allow both serial and parallel connec-
tion to a microprocessor. This flexible serial interface allows the
AD7891-1 to connect directly to Digital Signal Processors
(ADSP-2101, DSP56001, etc.) and Microcontrollers (8XC51,
68HC11, etc.). Full data on the AD7891-1 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
programmable +2.5 V ultra high precision bandgap reference,
and two AD713 quad op-amps to buffer the analog inputs.
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.
OPERATING THE AD7891-1 EVALUATION BOARD
Power Supplies
This evaluation board has four analog power supply inputs:
V_DD, DGND, +12 V and -12 V. The VDD supply is nominally
+5 V and is used to power the AD7891-1 and the on-board
digital integrated circuits. The +12 V and -12 V supplies are
used to power the AD713 quad op-amps and the AD780 voltage
reference. The DGND connection is to the digital ground
plane. This DGND ground plane connects to the AGND
ground plane at the AD7891-1. Therefore, it is recommended
not to connect AGND and DGND elsewhere in the system.
The various analog and digital supplies are provided through the
power-supply terminals on the board. When using the AD7891-
1 evaluation board with the EVAL-CONTROL BOARD, all
supplies are provided by the EVAL-CONTROL BOARD.
All supplies are decoupled to ground with 10 µF tantalum and
0.1 µF 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
0.1 µF capacitor.
AIN 8
FUNCTIONAL BLOCK DIAGRAM
Conversion
Start Input
9-Way
D-Type
Connector
Analog
Inputs
Range
Selection
Jumpers
AD7891-1 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
which may result from its use. No license is granted by implication or
otherwise under any patent or patent rights of Analog Devices.
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