EVAL-AD7475 Datasheet, PDF (1/13 Pages) Analog Devices – Evaluation Board for 1MSPS, 12-Bit ADC

a
Evaluation Board for 1MSPS, 12-Bit ADC
EVAL-AD7475/AD7495CB
FEATURES
Full-Featured Evaluation Board for the AD7475/95
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 AD7475/AD7495 which is a fast 12-bit high speed, low
power successive-approximation ADCs. The parts operate
from a sinlge 2.7 V to 5.25 V power supply and feature
throughput rates up to 1 MSPS. Full data on the
AD7475/AD7495 is available in the AD7475/AD7495
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.
OPERATING THE AD7475/AD7495 EVALUATION
BOARD
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 six
power supply inputs: V_DD, A_GND, +12V, -12V, A_GND, and
D_GND. If the evaluation board is used in stand-alone mode
+5V must be connected to the V_DD input to supply the
AD7475/AD7495 V_DD pin and the AD780 voltage refer-
ence. +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 AD7475/AD7495 AV_DD
supply pin is decoupled to A_GND with 10 µF tantalum and
0.1µF multilayer ceramic capacitors.
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 REFIN input and the VIN input.
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 AD7475/AD7495.
FUNCTIONAL BLOCK DIAGRAM
ANALOG
INPUT
EXTERNAL
REFERENCE
BIAS UP CIR-
CUIT
Vdd
AD7475/A
D7495 ^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.
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