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EVAL-AD9831EB

FEATURES

Full-Featured Evaluation Board for the AD9831

Various Linking Options

PC Software for Control of AD9831

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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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REV O

source via a BNC connector. Latches (74HC574) are also on

the board, these latches being used to hold the 16-bit data

word being written from the PC to the AD9831.

OPERATING THE AD9831 EVALUATION BOARD

Power Supplies

This evaluation board has two analog power supply inputs:

AVDD and AGND. AVDD equals +5 V or +3.3 V and is

used to provide the AVDD for the AD9831. DGND and

DVDD connections are also available. The DVDD is used to

provide the DVDD for the AD9831, the 25 MHz oscillator

and the DVDD for the logic chips. DGND and AGND are

connected at the AD9831. Therefore, it is recommended not

to connect AGND and DGND elsewhere in the system.

All power supplies are decoupled to ground. AVDD and

DVDD are decoupled using 10µF tantalum capacitors and

0.1µF ceramic capacitors at the input to the evaluation board.

The power supplies are again decoupled using 0.1µF capaci-

tors at the AD9831, the crystal and the logic.

Evaluation Board for the AD9831

Direct Digital Synthesizer

INTRODUCTION

This Application Note describes the evaluation board for the

AD9831 Direct Digital Synthesizer (DDS). The AD9831 is a

numerically controlled oscillator employing a phase accumula-

tor, a sine look-up table and a 10-bit D/A converter. The

part can be operated with clock frequencies up to 25 MHz.

Both phase modulation and frequency modulation can be per-

formed with the AD9831. Full data on the AD9831 is avail-

able in the AD9831 datasheet available from Analog Devices

and should be consulted in conjunction with this Application

Note when using the evaluation board.

The evaluation board interfaces to the parallel port of an IBM

compatible PC. Software is available with the evaluation

board which allows the user to easily program the AD9831.

Components on the AD9831 Evaluation Board include a 25

MHz oscillator which provides the MCLK for the AD9831.

The user can remove this oscillator, if required, and drive the

AD9831 with a different clock oscillator or an external clock

Evaluation Board Setup

Parallel Port Centronics

Printer Cable

IBM Compatible PC

AD9831.EXE

AD9831 Evaluation

Board

Summary of content (7 pages)

PAGE 1
a Evaluation Board for the AD9831 Direct Digital Synthesizer EVAL-AD9831EB FEATURES Full-Featured Evaluation Board for the AD9831 Various Linking Options PC Software for Control of AD9831 INTRODUCTION This Application Note describes the evaluation board for the AD9831 Direct Digital Synthesizer (DDS). The AD9831 is a numerically controlled oscillator employing a phase accumulator, a sine look-up table and a 10-bit D/A converter. The part can be operated with clock frequencies up to 25 MHz.
PAGE 2
EVAL-AD9831EB Link and Switch Options There are five link options which must be set for the required operating setup before using the evaluation board. The functions of these options are outlined below. Link No. LK1 Function The PSEL1 input can be controlled by the user via a BNC connector or, alternatively, by switch SW. When LK1 is arranged so that PSEL1 is connected to SW, the user can control the PSEL1 signal using the double throw switch.
PAGE 3
Preliminary Technical Data AD7002 EVAL-AD9831EB SET-UP CONDITIONS Care should be taken before applying power and signals to the evaluation board to ensure that all link positions are as per the required operating mode. Table 1 shows the position in which all the links are set when the evaluation board is sent out. 36-Way Connector Pin Description DGND Digital Ground. These lines are connected to the digital ground plane on the evaluation board. DB0 - DB7 Data Bit 0 to Data Bit 7.
PAGE 4
EVAL-AD9831EB Table 2. 36-Way Connector Pin Funtions PIN NO. 1 CONNECTORS There are three connectors on the AD9831 evaluation board as outlined in Table 4. MNEMONIC LATCH 2 D0 3 D1 4 D2 5 D3 6 D4 7 D5 8 D6 9 D7 14 RESET 19 DGND 20 DGND 21 DGND 22 DGND 23 DGND 24 DGND 25 DGND 26 DGND 27 DGND 28 DGND 29 DGND 30 DGND 31 LOAD 36 WR Table 4. Connector Functions Connector J1 Functions 36-Way Centronics Connector. J2 PCB Mounting Terminal Block.
PAGE 5
Preliminary Technical Data AD7002 EVAL-AD9831EB SOFTWARE DESCRIPTION Included in the EVAL-AD9831EB evaluation board package is a PC-compatible disk which contains software for controlling the AD9831 using the printer port of a PC. The disk contains the executable program which runs under Windows and it is advised that the user copy this file to the system hard disk to obtain optimum performance from the software. PC Configuration The executable program contains two menus.
PAGE 6
EVAL-AD9831EB The AD9831 software also contains a demonstration procedure whereby the AD9831 can be made to step through a series of output frequencies. The user only needs to load the start frequency, the stop frequency and the step size and, the AD9831 software will program the AD9831 appropriately so that a frequency sweep will be performed at the AD9831 output. Figure 3.
PAGE 7
Preliminary Technical Data 1 LATCH 2 3 D1 4 D2 5 6 D3 D4 7 8 D5 9 D7 D0 DVDD J1 PC Interface U2 WR RESET LATCH LOAD D6 10 DVDD AVDD 0.1µF C1, C2, C3 0.1µF VDD 74HC574 VDD PSEL1 R3 10KΩ R1 10KΩ RESET PSEL0 LK2 LK1 LK3 FSELECT MCLK DVDD DVDD SW AD9831 31 D0 34 WR 10 nF C7 REFIN 2 10 nF C8 FSADJUST 40 U4 A2 3 DVDD 10µF C10 J2 0.1µF C9 J3 AVDD 0.1µF C11 10µF C12 3.