EVAL-AD73322EB Datasheet, PDF (2/12 Pages) Analog Devices – EvaluationBoardforLowCost,LowPower, CMOSGerneralPurposeDualAnalogFrontEnd

EVAL-AD73322EB
Power Supply Circuit.
D.C. power between 8V & 12V is applied to the board through either connector J9 or J10 (positive is on the outer sleeve).
These connectors are connected together in a loop through arrangement which is intended for supplying the external voltage
to the EZ-KIT LITE which accompanies this evaluation board. The power supply shipped with the EZ-KIT Lite is suitable
for powering both the AD73322 board and the EZ-KIT LITE board. Diode, D1, prevents damage due to accidental reversal
of the supply. Regulator, U5, generates the +5V necessary for all the analog and digital circuitry on the board.
Clock Generator Circuit.
The oscillator, U8, provides two stable crystal controlled outputs of 16.384MHz or 8.192MHz. One of these frequencies
is selected by LK4 to produce the on-board generated clock signal. LK5 is used to select this clock signal or the EZ-KIT LITE
clock signal as the master clock (MCLK). MCLK is used as the main clock for the AD73322 and is also used for the external
synchronisation circuit for the SE and RESET signals. The board is shipped with 16.384MHz selected as the default clock
frequency.
Cascade Selector circuit.
This is programmed by software to determine the number of codecs in cascade. The 74HC253(U3) is a 2 channel 4-1
multiplexer which is automatically controlled by software to select which codec has its SDO and SDOFS returned to the DSP.
The process of downloading a user program automatically sets the multiplexer to the required setting. If the user develops
their own sample programs, then it is necessary to select the correct multiplexer settings for the cascade configuration. See
Table 1 for details of required multiplexer settings for various cascade settings.
Daughter Board.
The daughter board is used to provide easy configuration for using the demonstation programs provided with the evaluation
board. It provides circuitry for a stereo line input at stereo jack J13. These inputs are single-ended but are put through a pair
of single-ended to differential converters to provide two fully differential inputs at the two input channels of device U1. The
analog outputs of U1 are connected in a single-ended mode through an ac-coupling RC filter to provide an output which can
drive either the inputs of computer speakers or walkman headsets.
It is possible for the user to configure their own input circuitry on a similar daughter board. The daughter board dimensions
are detailed in Figure 9 .
OPERATING THE AD73322 EVALUATION BOARD
The AD73322 EVAL BOARD is designed to be interfaced directly to the EZ-KIT LITE which is an entry level demonstration
tool for the ADSP-2181 DSP. The interface to the EZ-KIT LITE is provided through the connector J11. Alternatively, the
board may be connected to the Texas Instrument TMS320C5XX EVM via connector J12.
Before applying power and signals to the evaluation board it is essential to ensure that all links are set as required for the desired
operating mode. The function of all links is explained below.
Link
Board
Function
LK1
LK2
LK3
LK4
LK5
Main Board
Main Board
Main Board
Main Board
Main Board
Connects TFS to RFS on DSP.
Connects SE to VDD or FL0 of DSP.
Connects RESET to FL2 or FL2 of DSP.
Selects between the 16.384MHz or 8.192MHz outputs from the on-board clock circuit.
Selects the on-board generated clock or DSP clock as the master clock for the board.
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REV. A