AD7899_EvalBoard| Application Note
a
Evaluation Board 400kSPS, 14-Bit ADC EVAL-AD7899CB
OPERATING THE AD7899 EVALUATION BOARD Power Supplies
FEATURES Full-Featured Evaluation Board for the AD7899 Eval-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 Eval-Board Controller INTRODUCTION
When using this evaluation board with the EVAL-BOARD CONTROLLER all supplies are provided from the EVALBOARD CONTROLLER through the 96 way connector. When using the board as a stand alone unit external supplies must be provided. This evaluation board has seven power supply inputs: VDD, AGND, +12V, -12V, AGND, VDRIVE and DGND. If the evaluation board is used in stand-alone mode +5V must be connected to the VDD input to supply the AD7899 VDD pin and the AD780 voltage reference. +12V and -12V are used to supply the op-amps. The VDRIVE 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 10uF tantalum and 0.1uF multilayer ceramic capacitors at the point where they enter the board. The supply pins of all the op-amps and reference are also decoupled to AGND with 10uF tantalum and a 0.1uF ceramic capacitor. The AD7899 AVDD supply pin is decoupled to AGND with 47uF tantalum and 0.1uF
multilayer ceramic capacitors. Extensive ground planes are used on this board to minimize the effect of high frequency noise interference. There are two ground planes, AGND and DGND. These are connected at one location close to the AD7899.
This Technical Note describes the evaluation board for the AD7899 high speed, low power, 14-bit A/D converter that operates from a single 5 V supply. Full data on the AD7899 is available in the AD7899 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 +2.5V ultra high precision bandgap reference and an op-amp for the analog inputs. 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-BOARD CONTROLLER which is also available from Analog Devices. External sockets are provided for the optional, external, CONVST and CLKIN and V DRIVE inputs and the VIN1-VIN4 inputs.
Fig. 1: FUNCTIONAL BLOCK DIAGRAM
AN AL O G IN P U T
A D7 899
EX T ER N A L R E F E R EN C E
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: 617/329-4700 Fax: 617/326-8703
96 W AY ED G E C O NN EC T O R
DIG ITA L I/O BU F FE RS
ANAL O G SIG N A L CO ND IT IO NIN G
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