50 MHz Direct Digital Synthesizer,

Waveform Generator

Data Sheet

AD9835

FEATURES

5 V power supply

50 MHz speed

On-chip COS lookup table

On-chip, 10-bit DAC

Serial loading

Power-down option

Temperature range: −40°C to +85°C

200 mW power consumption

16-Lead TSSOP

APPLICATIONS

Frequency stimulus/waveform generation

Frequency phase tuning and modulation

Low power RF/communications systems

Liquid and gas flow measurement

Sensory applications: proximity, motion, and defect

detection

Test and medical equipment

GENERAL DESCRIPTION

The AD9835 is a numerically-controlled oscillator employing

a phase accumulator, a COS lookup table, and a 10-bit digital-

to-analog converter integrated on a single CMOS chip. Modu-

lation capabilities are provided for phase modulation and

frequency modulation.

Clock rates of up to 50 MHz are supported. Frequency accuracy

can be controlled to one part in 4 billion. Modulation is effected

by loading registers through the serial interface. A power-down

bit allows the user to power down the AD9835 when it is not in

use; the power consumption reduces to 1.75 mW.

This part is available in a 16-lead TSSOP package.

Similar DDS products can be found at

http://www.analog.com/DDS.

FUNCTIONAL BLOCK DIAGRAM

IOUT

COMP

REFIN

FS ADJUST

REFOUT

AGND

AVDD

DGND

DVDD

MCLK

PSEL0 PSEL1

12

AD9835

ON-BOARD

REFERENCE

10-BIT DAC

PHASE0 REG

PHASE1 REG

PHASE2 REG

PHASE3 REG

FULL-SCALE

CONTROL

COS

ROM

PHASE

ACCUMULATOR

(32 BIT)

FREQ0 REG

FREQ1 REG

16-BIT DATA REGISTER

SYNC

FSELECT

FSELECT

BIT

SELSRC

SYNC

8 LSBs

8 MSBs

DECODE LOGIC

FSYNC

SCLK

SDATA

SERIAL REGISTER

CONTROL REGISTER

FSELECT/PSEL REGISTER

DEFER REGISTER

SYNC

SYNC

SELSRC

PSEL0

BIT

PSEL1

BIT

MUX

MUX

MUX

Figure 1.

Rev. A

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