EVAL-AD7898CB Datasheet, PDF (1/13 Pages) Analog Devices – Evaluation Board for 5V, 12-Bit, Serial 220kSPS ADC in 8-Pin Package

a
Evaluation Board for 5V, 12-Bit, Serial
220kSPS ADC in 8-Pin Package
EVAL-AD7898CB
FEATURES
OPERATING THE AD7898 EVALUATION BOARD
Full-Featured Evaluation Board for the AD7898
EVALUATION-BOARD CONTROLLER Compatible
Stand Alone Capability
On-Board Analog Buffering and Reference
Various Linking Options
PC Software for Control and Data Analysis when used
with EVALUATION-BOARD CONTROLLER
Patchwork Area for User Expansion
INTRODUCTION
This Technical Note describes the evaluation board for
the AD7898 which is a fast 12-bit ADC that operates from a
single +5 V supply and is housed in an 8-pin SOIC. Full data
on the AD7898 is available in the AD7898 data sheet
available from Analog Devices and should be consulted in
conjunction with this Technical Note when using the
Evaluation Board.
On-board components include an AD780 which is a pin
programmable +2.5V or +3V ultra high precision
bandgap reference and an AD711 op-amp used to buffer
the analog input. There are various link options which are
explained in detail on page 2.
Interfacing to this board is through a 96-way connector.
This 96-way connector is compatible with the EVALUA-
TION-BOARD CONTROLLER which is also available
from Analog Devices. External sockets are provided for
the CS/CONVST input, VDRIVE input, SDATA input,
SCLK input, REFIN input and the VIN input.
Power Supplies
When using this evaluation board with the EVALUA-
TION-BOARD CONTROLLER all supplies are pro-
vided from the EVALUATION-BOARD
CONTROLLER through the 96 way connector.
When using the board as a stand alone unit external sup-
plies must be provided. This evaluation board has seven
power supply inputs: V_DD, A_GND, +12V, -12V, A_GND, and
V_DRIVE. If the evaluation board is used in stand-alone
mode +5V must be connected to the V_DD input to supply
the AD7898 V_DD pin and the AD780 voltage reference.
+12V and -12V are used to supply the op-amps. The
V_DRIVE pin can be driven by a voltage between +3V and
+5V allowing the evaluation board to be connected to
both +3V and +5V systems. The supplies are decoupled to
the relevant ground plane with 10µF tantalum and 0.1µF
multilayer ceramic capacitors at the point where they enter
the board. The supply pins of all the op-amps and refer-
ence are also decoupled to A_GND with 10µF tantalum and a
0.1µF ceramic capacitor. The AD7898 AV_DD supply pin is
decoupled to A_GND with 10 µF tantalum and 0.1µF multi-
layer ceramic capacitors.
Extensive ground planes are used on this board to mini-
mize the effect of high frequency noise interference. There
are two ground planes, A_GND and D_GND. These are con-
nected at one location close to the AD7898.
FUNCTIONAL BLOCK DIAGRAM
ANALOG
INPUT
EXTERNAL
REFERENCE
Vdd
ad7898
CS
SDATA
SCLK
Vdrive
Vdd
REV. 0
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]