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a

Evaluation Board for 1MSPS, 12-Bit ADC

EVAL-AD7475/AD7495CB

FUNCTIONAL BLOCK DIAGRAM

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.

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.

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

ence. +12V and -12V are used to supply the op-amps. The

+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-

0.1µF multilayer ceramic capacitors.

Extensive ground planes are used on this board to mini-

mize the effect of high frequency noise interference. There

nected at one location close to the AD7475/AD7495.

AD7475/A

D7495

EXTERNAL

REFERENCE

ANALOG

INPUT

CS

SDATA

SCLK

Vdd

Vdrive

Vdd

BIAS UP CIR-

CUIT