EVAL-AD7476 Datasheet, PDF (1/12 Pages) Analog Devices – Evaluation Board for 1MSPS, 12-/ 10-Bit ADCs

a
Evaluation Board for 1MSPS,
12-/ 10-Bit ADCs
EVAL-AD7476/77CB
FEATURES
Full-Featured Evaluation Board for the AD7476/
AD7477
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 Technical Note describes the evaluation board for
the AD7476/77. The AD7476/77 are, respectively, 12 bit
and 10 bit, high speed, low power, successive-approxima-
tion ADC's. The parts operate from a single 2.35 V to
5.25 V power supply and feature throughtput rates up to
1MSPS. The parts contain a low-noise, wide bandwidth
track/hold amplifier which can handle input frequencies in
excess of 1MHz. Full data on the AD7476/77 is available
in the AD7476/77 data sheet available from Analog De-
vices 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 +2.5 V or +3 V ultra high precision
bandgap reference, an OP467 quad op-amp used to buffer
the analog inputs and the REF195 precision bandgap,
voltage reference, providing a 5 V reference voltage.
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 EVAL-
CONTROL BOARD which is also available from Analog
Devices. External sockets are provided for the AIN input,
the VIN input and the VBIASED input.
OPERATING THE AD7476/77 EVALUATION BOARD
Power Supplies
When using this evaluation board with the EVAL-CON-
TROL BOARD all supplies are provided from the EVAL-
CONTROL BOARD 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: AV_DD, A_GND, +12 V, -12 V, A_GND,
DV_DD and D_GND. +5 V must be connected to the AV_DD
input to supply the AD780 and the Ref195 voltage refer-
ence. The V_DD for the AD7476/77 can be supplied from
either the AVDD external supply or from the selected
voltage reference chip. +12 V and -12 V are used to sup-
ply the OP467 quad op-amp. 0V is connected to one or
both of the A_GND inputs. The DV_DD input can be used to
supply a separate +5V for the 74LS04 DV_DD pin. The
D_GND input must be tied to 0V. The supplies are de-
coupled 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 the quad
op-amp and references are also decoupled to A_GND with
10µF tantalum and a 0.1µF ceramic capacitors. The
AD7476/77 AV_DD supply pin is decoupled to A_GND with
10uF tantalum and 0.1µF multilayer 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 AD7476/77.
Figure 1. FUNCTIONAL BLOCK DIAGRAM
External
Power Supplies
Voltage
Reference
Input Buffer
Vdd
CS
AD7476/77
ADC
SCLK
VIN
SDATA
96 Pin
DIN
Connector
Bias-up
Circuit
Power
Supply
Circuit
REV. 0
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