AD9833 [ADI]

+2.5 V to +5.5 V, 25 MHz Low Power CMOS Complete DDS; + 2.5V至+ 5.5V , 25 MHz的低功耗CMOS DDS完成
AD9833
型号: AD9833
厂家: ADI    ADI
描述:

+2.5 V to +5.5 V, 25 MHz Low Power CMOS Complete DDS
+ 2.5V至+ 5.5V , 25 MHz的低功耗CMOS DDS完成

数据分配系统
文件: 总18页 (文件大小:206K)
中文:  中文翻译
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PRELIMINARY TECHNICAL DATA  
+2.5 V to +5.5 V, 25 MHz Low Power  
a
Preliminary Technical Data  
CMOSCompleteDDS  
AD9833  
with a power supply from +2.3 V to +5.5 V.  
FEATURES  
+2.3 V to +5.5 V Power Supply  
25 MHz Speed  
Tiny 10-Pin µSOIC Package  
Serial Loading  
Sinusoidal/Triangular DAC Output  
Power-Down Option  
Narrowband SFDR > 72 dB  
20 mW Power Consumption at 3 V  
Capability for phase modulation and frequency modula-  
tion is provided. Frequency accuracy can be controlled to  
one part in 0.25 billion. Modulation is effected by loading  
registers through the serial interface.  
The AD9833 offers a variety of output waveforms from  
the VOUT pin. The SIN ROM can be bypassed so that a  
linear up/down ramp is output from the DAC. If the SIN  
ROM is not by-passed, a sinusoidal output is available.  
Also, if a clock output is required, the MSB of the DAC  
data can be output.  
APPLICATIONS  
Digital Modulation  
Portable Equipment  
Test Equipment  
DDS Tuning  
The digital section is internally operated at +2.5 V, irre-  
spective of the value of VDD, by an on board regulator  
which steps down VDD to +2.5 V, when VDD exceeds  
+2.5 V.  
The AD9833 has a power-down function (SLEEP). This  
allows sections of the device which are not being used to  
be powered down, thus minimising the current consump-  
tion of the part e.g the DAC can be powered down when a  
clock output is being generated.  
GENERAL DESCRIPTION  
This low power DDS device is a numerically controlled  
oscillator employing a phase accumulator, a SIN ROM  
and a 10-bit D/A converter integrated on a single  
CMOS chip. Clock rates up to 25 MHz are supported  
The AD9833 is available in a 10-pin µSOIC package.  
FUNCTIONAL BLOCK DIAGRAM  
CAP/2.5V  
VDD  
DGND  
AGND  
MCLK  
On-Board  
Reference  
Regulator  
2.5V  
AVDD/  
DVDD  
FullScale  
Control  
COMP  
FREQ0 REG  
FREQ1 REG  
12  
Phase  
Accumulator  
(28 Bit)  
SIN  
ROM  
10-Bit DAC  
MUX  
Σ
MUX  
MSB  
PHASE0 REG  
PHASE1 REG  
MUX  
DIV BY  
2
MUX  
VOUT  
Control Register  
R
200  
Serial Interface  
&
AD9833  
Control Logic  
FSYNC  
SCLK  
SDATA  
REV PrG 02/02  
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: 781/329-4700  
Fax: 781/326-8703  
www.analog.com  
© Analog Devices, Inc., 2002  
PRELIMINARY TECHNICAL DATA  
AD9833  
(VDD = +2.3 V to +5.5 V; AGND = DGND = 0 V; TA = TMIN to TMAX; RSET = 6.8 kfor  
VOUT unless otherwise noted)  
SPECIFICATIONS1  
Parameter  
Min  
Typ  
Max  
Units  
TestConditions/Comments  
SIGNALDACSPECIFICATIONS  
Resolution  
10  
Bits  
MSPS  
V
Update Rate (fMAX  
)
25  
0.8  
OutputCompliance2  
DCAccuracy:  
IntegralNonlinearity  
DifferentialNonlinearity  
1
0.5  
LSB  
LSB  
DDSSPECIFICATIONS  
DynamicSpecifications:  
Signal to Noise Ratio  
50  
dB  
fMCLK = 25 MHz, fOUT = 1.5 kHz  
Total Harmonic Distortion  
SpuriousFreeDynamicRange(SFDR):  
Wideband ( 2 MHz)  
-53  
dBc  
fMCLK = 25 MHz, fOUT = 1.5 kHz  
50  
55  
72  
75  
dBc  
dBc  
dBc  
dBc  
dBc  
ms  
fMCLK = 25 MHz, fOUT = fMCLK/3  
MCLK = 25 MHz, fOUT = 0.5 MHz  
f
NarrowBand ( 50 kHz)  
fMCLK = 25 MHz, fOUT = fMCLK/3  
fMCLK = 25 MHz, fOUT = 0.5 MHz  
ClockFeedthrough  
Wake Up Time  
–55  
1
OUTPUT BUFFER  
OutputRise/FallTime  
Output Jitter  
20  
100  
ns  
ps rms  
Using a 15 pF Load  
When DAC data MSB is output  
VOLTAGEREFERENCE  
InternalReference  
1.116  
1.2  
1.284  
V
1.2 V 7ꢀ  
LOGICINPUTS  
V
INH, Input High Voltage  
VDD –0.9  
VDD - 0.5  
2
V
V
V
V
V
µA  
pF  
+3.6 V to +5.5 V Power Supply  
+2.7 V to +3.6 V Power Supply  
+2.3 V to + 2.7 V Power Supply  
+3.6 V to +5.5 V Power Supply  
+2.3 V to + 3.6 V Power Supply  
VINL, Input Low Voltage  
0.9  
0.5  
1
IINH, Input Current  
CIN, InputCapacitance  
10  
POWERSUPPLIES  
VDD  
fMCLK = 25 MHz, fOUT = fMCLK/7  
2.3  
5.5  
5
V
3
IAA  
IDD  
mA  
mA  
mA  
mA  
mA  
3
1 + 0.04/MHz  
7
10  
0.25  
3
IAA + IDD  
10  
15  
3 V Power Supply  
5 V Power Supply  
DAC and Internal Clock Powered Down  
Low Power Sleep Mode3  
NOTES  
1Operating temperature range is as follows: B Version: –40°C to +85°C; typical specifications are at 25؇C  
2Guaranteed by Design.  
3Measured with the digital inputs static and equal to 0 V or DVDD.  
Specifications subject to change without notice. There is 95ꢀ test coverage of the digital circuitry.  
–2–  
REV PrG  
PRELIMINARY TECHNICAL DATA  
AD9833  
100nF  
VDD  
10nF  
COMP  
CAP/2.5V  
REGULATOR  
12  
VOUT  
SIN  
ROM  
10-BIT DAC  
20pF  
AD9833  
Figure 1. Test Circuit With which Specifications are tested.  
TIMINGCHARACTERISTICS1  
(VDD = +2.3 V to +5.5 V; AGND = DGND = 0 V, unless otherwise noted)  
Parameter Limit at TMIN to TMAX  
Units  
TestConditions/Comments  
t1  
t2  
t3  
t4  
t5  
t6  
t7  
t8  
40  
16  
16  
25  
10  
10  
5
10  
t4 - 5  
5
ns min  
ns min  
ns min  
ns min  
ns min  
ns min  
ns min  
ns min  
ns max  
ns min  
ns min  
MCLK Period  
MCLK High Duration  
MCLK Low Duration  
SCLK Period  
SCLK High Duration  
SCLK Low Duration  
FSYNC to SCLK Falling Edge Setup Time  
FSYNC to SCLK Hold Time  
t9  
t10  
Data Setup Time  
Data Hold Time  
3
1 Guaranteed by design, not production tested.  
t1  
MCLK  
t2  
t3  
Figure 2. Master Clock  
t5  
t4  
SCLK  
t7  
t8  
t6  
FSYNC  
t10  
t9  
D15  
D14  
D2  
D1  
D0  
D15  
D14  
SDATA  
Figure 3. Serial Timing  
CAUTION  
ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily  
accumulate on the human body and test equipment and can discharge without detection.  
Although the AD9833 features proprietary ESD protection circuitry, permanent damage may  
occur on devices subjected to high energy electrostatic discharges. Therefore, proper ESD  
precautions are recommended to avoid performance degradation or loss of functionality.  
REV PrG  
–3–  
PRELIMINARY TECHNICAL DATA  
AD9833  
ABSOLUTE MAXIMUM RATINGS*  
(TA = +25°C unless otherwise noted)  
Maximum Junction Temperature . . . . . . . . . . . . . . 150°C  
µSOIC Package  
θJA Thermal Impedance . . . . . . . . . . . . . . . . . . .206°C/W  
θJC Thermal Impedance . . . . . . . . . . . . . . . . . . . 44°C/W  
Lead Temperature, Soldering (10 sec) . . . . . . . . . 300°C  
IR Reflow, Peak Temperature . . . . . . . . . . . . . . . 220°C  
VDD to AGND . . . . . . . . . . . . . . . . . . . . . –0.3 V to +6 V  
VDD to DGND . . . . . . . . . . . . . . . . . . . . . –0.3 V to +6 V  
AGND to DGND. . . . . . . . . . . . . . . . . . –0.3 V to +0.3 V  
CAP/2.5V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.75 V  
Digital I/O Voltage to DGND . –0.3 V to VDD + 0.3 V  
Analog I/O Voltage to AGND . –0.3 V to VDD + 0.3 V  
Operating Temperature Range  
*StressesabovethoselistedunderAbsoluteMaximumRatingsmaycausepermanent  
damagetothedevice. Thisisastressratingonlyandfunctionaloperationofthedevice  
at these or any other conditions above those listed in the operational sections of this  
specification is not implied. Exposure to absolute maximum rating conditions for  
extendedperiodsmayaffectdevicereliability.  
Industrial (B Version) . . . . . . . . . . . . . . –40°C to +85°C  
Storage Temperature Range . . . . . . . . . –65°C to +150°C  
ORDERING GUIDE  
Model  
Temperature Range  
Package Description  
Package Option  
AD9833BRM  
40°C to +85°C  
14-Pin µSOIC  
(Micro Small Outline IC  
)
RM-10  
EVAL-AD9833EB  
Evaluation Board  
PIN CONFIGURATION  
10  
9
1
2
COMP  
VDD  
VOUT  
AGND  
FSYNC  
SCLK  
AD9833  
8
7
6
CAP/2.5V  
DGND  
3
4
5
TOP VIEW  
(Not to Scale)  
SDATA  
MCLK  
PIN DESCRIPTION  
Pin #  
Mnemonic  
Function  
POWER SUPPLY  
2
3
VDD  
Positive power supply for the analog section and the digital interface sections. The on board 2.5 V  
regulator is also supplied from VDD. VDD can have a value from +2.3 V to +5.5 V. A 0.1 µF and  
10 µF decoupling capacitor should be connected between VDD and AGND.  
CAP/2.5V The digital circuitry operates from a +2.5 V power supply. This +2.5 V is generated from VDD  
using an on board regulator (when VDD exceeds +2.7 V). The regulator requires a decoupling  
capacitor of typically 100 nF, which is connected from CAP/2.5V to DGND. If VDD is equal to  
or less than +2.7 V, CAP/2.5V should be tied directly to VDD.  
4
9
DGND  
AGND  
Digital Ground.  
Analog Ground.  
ANALOG SIGNAL AND REFERENCE  
1
10  
COMP  
VOUT  
A DAC Bias Pin. This pin is used for de-coupling the DAC bias voltage.  
Voltage Output. The analog and digital output from the AD9833 is available at this pin. An  
external load resistor is not required as the device has a 200W resistor on board.  
DIGITAL INTERFACE AND CONTROL  
5
MCLK  
Digital Clock Input. DDS output frequencies are expressed as a binary fraction of the frequency of  
MCLK. The output frequency accuracy and phase noise are determined by this clock.  
Serial Data Input. The 16-bit serial data word is applied to this input.  
Serial Clock Input. Data is clocked into the AD9833 on each falling SCLK edge.  
Active Low Control Input. This is the frame synchronisation signal for the input data. When  
FSYNC is taken low, the internal logic is informed that a new word is being loaded into the  
device.  
6
7
8
SDATA  
SCLK  
FSYNC  
–4–  
REV PrG  
PRELIMINARY TECHNICAL DATA  
TypicalPerformanceCharacteristics  
AD9833  
TBD  
TBD  
TBD  
TPC 3. Wide Band SFDR vs. MCLK  
Frequency  
TPC 2. Narrow Band SFDR vs. MCLK  
Frequency  
TPC 1. Typical Current Consumption  
vs. MCLK Frequency  
TBD  
TBD  
TBD  
TPC 6. SNR vs. fOUT/fMCLK for  
Various MCLK Frequencies  
TPC 5. SNR vs. MCLK Frequency  
TPC 4. Wide Band SFDR vs. fOUT/fMCLK  
for Various MCLK Frequencies  
TBD  
TPC 7. Wake-Up Time vs.  
Temperature  
REV PrG  
–5–  
PRELIMINARY TECHNICAL DATA  
AD9833  
TypicalPerformanceCharacteristics  
TBD  
TBD  
TBD  
TPC 11. fMCLK = 10 MHz; fOUT = 3.33 kHz  
= fMCLK/3 ;  
TPC 10. fMCLK = 10 MHz; fOUT = 1.43 kHz  
= fMCLK/7 ;  
TPC 9. fMCLK = 10 MHz; fOUT = 2.4 kHz;  
Frequency Word = 000FBA9  
Frequency Word = 5555555  
Frequency Word = 2492492  
TBD  
TBD  
TBD  
TPC 14. fMCLK = 25 MHz; fOUT = 600 kHz;  
Frequency Word = 0624DD3  
TPC 13. fMCLK = 25 MHz; fOUT = 60 kHz;  
Frequency Word = 009D495  
TPC 12. fMCLK = 25 MHz; fOUT = 6 kHz;  
Frequency Word = 000FBA9  
TBD  
TBD  
TBD  
TPC 17. fMCLK = 25 MHz;  
OUT = 8.333 MHz = fMCLK/3 ;  
Frequency Word = 555475C  
TPC 16. fMCLK = 25 MHz;  
fOUT = 3.857 MHz = fMCLK/7 ;  
Frequency Word = 277EE4F  
TPC 15. fMCLK = 25 MHz;  
f
f
OUT = 2.4 MHz;  
Frequency Word = 189374D  
6–  
REV PrG  
PRELIMINARY TECHNICAL DATA  
AD9833  
TERMINOLOGY  
THEORY OF OPERATION  
Sine waves are typically thought of in terms of their  
Integral Nonlinearity  
magnitude form a(t) = sin (ωt). However, these are  
nonlinear and not easy to generate except through piece  
wise construction. On the other hand, the angular  
information is linear in nature. That is, the phase angle  
rotates through a fixed angle for each unit of time. The  
angular rate depends on the frequency of the signal by the  
traditional rate of ω = 2πf.  
This is the maximum deviation of any code from a  
straight line passing through the endpoints of the transfer  
function. The endpoints of the transfer function are zero  
scale, a point 0.5 LSB below the first code transition  
(000 . . . 00 to 000 . . . 01) and full scale, a point 0.5 LSB  
above the last code transition (111 . . . 10 to 111 . . . 11).  
The error is expressed in LSBs.  
Differential Nonlinearity  
This is the difference between the measured and ideal 1  
LSB change between two adjacent codes in the DAC. A  
specified differential nonlinearity of 1 LSB maximium ensures  
monotonicity.  
MAGNITUDE  
+1  
0
Output Compliance  
- 1  
The output compliance refers to the maximum voltage  
that can be generated at the output of the DAC to meet  
the specifications. When voltages greater than that speci-  
fied for the output compliance are generated, the AD9833  
may not meet the specifications listed in the data sheet.  
PHASE  
2π  
0
Spurious Free Dynamic Range  
Along with the frequency of interest, harmonics of the  
fundamental frequency and images of the these frequencies  
are present at the output of a DDS device. The spurious  
free dynamic range (SFDR) refers to the largest spur or  
harmonic which is present in the band of interest. The  
wide band SFDR gives the magnitude of the largest har-  
monic or spur relative to the magnitude of the fundamental  
frequency in the 0 to Nyquist bandwidth. The narrow band  
SFDR gives the attenuation of the largest spur or harmonic  
Figure 4. Sine Wave  
Knowing that the phase of a sine wave is linear and given  
a reference interval (clock period), the phase rotation for  
that period can be determined.  
Phase = ωδt  
Solving for ω  
ω = Phase/δt = 2πf  
in a bandwidth of  
quency.  
200 kHz about the fundamental fre-  
Solving for f and substituting the reference clock  
frequency for the reference period (1/fMCLK = δt)  
Total Harmonic Distortion  
f = Phase x fMCLK/2π  
Total Harmonic Distortion (THD) is the ratio of the rms  
sum of harmonics to the rms value of the fundameltal. For  
the AD9834, THD is defined as:  
The AD9833 builds the output based on this simple  
equation. A simple DDS chip can implement this  
equation with three major subcircuits:  
Numerical Controlled Oscillator + Phase Modulator  
SIN ROM  
2
2
2
2
2
THD = 20 log√(V2 + V3 + V4 + V5 + V6 )/V1  
where V1 is the rms amplitude of the fundamental and V2,  
V3, V4, V5 and V6 are the rms amplitudes of the second  
through thre sixth harmonic.  
Digital- to- Analog Convertor.  
Each of these sub-circuits are discussed in the following  
section.  
Signal-to-Noise Ratio (SNR)  
S/N is the ratio of the rms value of the measured output  
signal to the rms sum of all other spectral components  
below the Nyquist frequency, excluding the first six har-  
monics and dc. The value for SNR is expressed in  
decibels.  
Clock Feedthrough  
There will be feedthrough from the MCLK input to the  
analog output. Clock feedthrough refers to the magnitude  
of the MCLK signal relative to the fundamental frequency  
in the AD9834’s output spectrum.  
REV PrG  
7–  
PRELIMINARY TECHNICAL DATA  
AD9833  
CIRCUIT DESCRIPTION  
phase resolution more than the 10-bit DAC.  
The SIN ROM is enabled using the MODE bit (D1) in  
the control register. This is explained further in Table 11.  
The AD9833 is a fully integrated Direct Digital Synthesis  
(DDS) chip. The chip requires one reference clock, one  
low precision resistor and decoupling capacitors to pro-  
vide digitally created sine waves up to 12.5 MHz. In  
addition to the generation of this RF signal, the chip is  
fully capable of a broad range of simple and complex  
modulation schemes. These modulation schemes are fully  
implemented in the digital domain allowing accurate and  
simple realization of complex modulation algorithms us-  
ing DSP techniques.  
The internal circuitry of the AD9833 consists of the fol-  
lowing main sections: a Numerical Controlled Oscillator  
(NCO), Frequency and Phase Modulators, SIN ROM, a  
Digital-to-Analog Converter, and a Regulator.  
Digital-to-Analog Converter  
The AD9833 includes a high impedance current source  
10-bit DAC. The DAC receives the digital words from  
the SIN ROM and converts them into the corresponding  
analog voltages.  
The DAC is configured for single-ended operation. An  
external load resistor is not required as the device has a  
200 resistor on board. The DAC generates an output  
voltage of typically 0.6 Vpp.  
Regulator  
VDD provides the power supply required for the analog  
section and the digital section of the AD9833. This supply  
can have a value of +2.3V to +5.5V  
The internal digital section of the AD9833 is operated at  
2.5 V. An on-board regulator steps down the voltage ap-  
plied at VDD to 2.5 V. When the applied voltage at the  
VDD pin of the AD9833 is equal to or less than 2.7 V,  
the pins CAP/2.5V and VDD should be tied together, thus  
by-passing the on-board regulator.  
Numerical Controlled Oscillator + Phase Modulator  
This consists of two frequency select registers, a phase  
accumulator, two phase offset registers and a phase offset  
adder. The main component of the NCO is a 28-bit phase  
accumulator which assembles the phase component of the  
output signal. Continuous time signals have a phase range  
of 0 to 2. Outside this range of numbers, the sinusoid  
functions repeat themselves in a periodic manner. The  
digital implementation is no different. The accumulator  
simply scales the range of phase numbers into a multibit  
digital word. The phase accumulator in the AD9833 is  
implemented with 28 bits. Therefore, in the AD9833, 2␲  
= 228. Likewise, the Phase term is scaled into this range  
of numbers 0 < Phase < 228 – 1. Making these substitu-  
tions into the equation above  
f = Phase x fMCLK/228  
where 0 < Phase < 228 - 1.  
The input to the phase accumulator (i.e., the phase step)  
can be selected either from the FREQ0 Register or  
FREQ1 Register and this is controlled by the FSELECT  
bit. NCOs inherently generate continuous phase signals,  
thus avoiding any output discontinuity when switching  
between frequencies.  
Following the NCO, a phase offset can be added to  
perform phase modulation using the 12-bit Phase  
Registers. The contents of one of these phase registers is  
added to the most significant bits of the NCO. The  
AD9833 has two Phase registers, the resolution of these  
registers being 2π/4096.  
SIN ROM  
To make the output from the NCO useful, it must be  
converted from phase information into a sinusoidal value.  
Since phase information maps directly into amplitude, the  
SIN ROM uses the digital phase information as an ad-  
dress to a look-up table, and converts the phase  
information into amplitude. Although the NCO contains a  
28-bit phase accumulator, the output of the NCO is trun-  
cated to 12 bits. Using the full resolution of the phase  
accumulator is impractical and unnecessary as this would  
require a look-up table of 228 entries. It is necessary only  
to have sufficient phase resolution such that the errors due  
to truncation are smaller than the resolution of the 10-bit  
DAC. This requires the SIN ROM to have two bits of  
8–  
REV PrG  
PRELIMINARY TECHNICAL DATA  
AD9833  
FUNCTIONAL DESCRIPTION  
reset the phase, frequency or control registers. These reg-  
isters will contain invalid data and, therefore, should be set  
to a known value by the user. The RESET bit should then  
be set to 0 to begin generating an output. A signal will  
appear at the DAC output 7 MCLK cycles after RESET is  
set to 0.  
Serial Interface  
The AD9833 has a standard 3-wire serial interface, which  
is compatible with SPI, QSPI, MICROWIRE and DSP  
interface standards.  
Data is loaded into the device as a 16-bit word under the  
control of a serial clock input, SCLK. The timing dia-  
gram for this operation is given in Figure 3.  
Latency  
Associated with each asynchronous write operation in the  
AD9833 is a latency. If a selected frequency/phase register  
is loaded with a new word there is a delay of 7 to 8 MCLK  
cycles before the analog output will change. (There is an  
uncertainty of one MCLK cycle as it depends on the posi-  
tion of the MCLK rising edge when the data is loaded into  
the destination register.)  
The FSYNC input is a level triggered input that acts as a  
frame synchronisation and chip enable. Data can only be  
transferred into the device when FSYNC is low. To start  
the serial data transfer, FSYNC should be taken low, ob-  
serving the minimum FSYNC to SCLK falling edge setup  
time, t7. After FSYNC goes low, serial data will be shifted  
into the device's input shift register on the falling edges of  
SCLK for 16 clock pulses. FSYNC may be taken high  
after the sixteenth falling edge of SCLK, observing the  
minimum SCLK falling edge to FSYNC rising edge time,  
t8. Alternatively, FSYNC can be kept low for a multiple of  
16 SCLK pulses, and then brought high at the end of the  
data transfer. In this way, a continuous stream of 16 bit  
words can be loaded while FSYNC is held low, FSYNC  
only going high after the 16th SCLK falling edge of the  
last word loaded.  
The Control Register  
The AD9833 contains a 16-bit control register which sets  
up the AD9833 as the user wishes to operate it. All control  
bits, except MODE, are sampled on the internal negative  
edge of MCLK.  
Table 2, on the following page, describes the individual  
bits of the control register. The different functions and the  
various output options from the AD9833 are described in  
more detail in the section following Table 2.  
To inform the AD9833 that you wish to alter the contents  
of the Control register, D15 and D14 must be set to '0' as  
shown below.  
The SCLK can be continuous or, alternatively, the SCLK  
can idle high or low between write operations.  
Powering up the AD9833  
The flow chart in Figure 6 shows the operating routine for  
the AD9833. When the AD9833 is powered up, the part  
should be reset. This will reset appropriate internal regis-  
ters to zero to provide an analog output of midscale. To  
avoid spurious DAC outputs while the AD9833 is being  
initialized, the RESET bit should be set to 1 until the part  
is ready to begin generating an output. RESET does not  
Table 1. Control Register  
D15 D14 D13  
D0  
0
0
CONTROL BITS  
SLEEP12  
SLEEP1  
AD9833  
SIN  
ROM  
(Low Power)  
10-Bit DAC  
0
Phase  
Accumulator  
(28 Bit)  
MUX  
1
RESET  
MODE + OPBITEN  
DIGITAL  
OUTPUT  
1
VOUT  
MUX  
0
DIV BY  
2
(enable)  
DIV2  
OPBITEN  
DB15 DB14 DB13 DB12 DB11  
DB10  
DB9 DB8  
DB7  
DB6  
DB5  
DB4  
0
DB3  
DIV2  
DB2 DB1  
MODE  
DB0  
0
0
0
B28  
HLB FSELECT PSELECT  
0
RESET SLEEP1 SLEEP12 OPBITEN  
0
Figure 5. Function of Control Bits  
REV PrG  
9–  
PRELIMINARY TECHNICAL DATA  
AD9833  
Table 2. Description of bits in the Control Register  
Bit  
Name  
Function  
D13  
B28  
Two write operations are required to load a complete word into either of the Frequency registers.  
B28 = '1' allows a complete word to be loaded into a frequency register in two consecutive  
writes. The first write contains the 14 LSBs of the frequency word and the next write will  
contain the 14 MSBs. The first two bits of each sixteen-bit word define the frequency register to  
which the word is loaded, and should therefore be the same for both of the consecutive writes.  
Refer to table 6 for the appropriate addresses. The write to the frequency register occurs after both  
words have been loaded, so the register never holds an intermediate value. An example of a com-  
plete 28-bit write is shown in table 5.  
When B28 = '0' the 28-bit frequency register operates as 2 14-bit registers, one containing the 14  
MSBs and the other containing the 14 LSBs. This means that the 14 MSBs of the frequency  
word can be altered independent of the 14 LSBs and vice versa. To alter the 14 MSBs or the 14  
LSBs, a single write is made to the appropriate Frequency address. The control bit D12 (HLB)  
informs the AD9833 whether the bits to be altered are the 14 MSBs or 14 LSBs.  
This control bit allows the user to continuously load the MSBs or LSBs of a frequency register  
while ignoring the remaining 14 bits. This is useful if the complete 28 bit resolution is not re-  
quired. HLB is used in conjunction with D13 (B28). This control bit indicates whether the 14 bits  
being loaded are being transferred to the 14 MSBs or 14 LSBs of the addressed frequency regis-  
ter. D13 (B28) must be set to '0' to be able to change the MSBs and LSBs of a frequency word  
seperately. When D13 (B28) = '1', this control bit is ignored.  
D12  
HLB  
HLB = '1' allows a write to the 14 MSBs of the addressed frequency register.  
HLB = '0' allows a write to the 14 LSBs of the addressed frequency register.  
The FSELECT bit defines whether the FREQ0 register or the FREQ1 register is used in the  
phase accumulator.  
The PSELECT bit defines whether the PHASE0 register or the PHASE1 register data is added to  
the output of the phase accumulator.  
D11  
D10  
FSELECT  
PSELECT  
D9  
D8  
Reserved  
RESET  
This bit should be set to 0.  
RESET = '1' resets internal registers to zero, which corresponds to an analog output of midscale.  
RESET = '0' disables Reset. This function is explained further in Table 9.  
When SLEEP1 = '1', the internal MCLK clock is disabled. The DAC output will remain at its  
present value as the NCO is no longer accumulating.  
When SLEEP1 = '0' MCLK is enabled. This function is explained further in Table 10.  
SLEEP12 = '1' powers down the on-chip DAC. This is useful when the AD9833 is used to output  
the MSB of the DAC data.  
SLEEP12 = '0' implies that the DAC is active. This function is explained further in Table 10.  
The function of this bit, in association with D1 (MODE), is to control what is output at the  
VOUT pin. This is explained further in Table 11.  
D7  
D6  
D5  
SLEEP1  
SLEEP12  
OPBITEN  
When OPBITEN = '1' the output of the DAC is no longer available at the VOUT pin. Instead,  
the MSB (or MSB/2) of the DAC data is connected to the VOUT pin. This is useful as a coarse  
clock source. The bit DIV2 controls whether it is the MSB or MSB/2 that is ouput.  
When OPBITEN equals 0, the DAC is connected to VOUT. The MODE bit determines whether  
it is a sinusoidal or a ramp output that is available.  
D4  
D3  
Reserved  
DIV2  
This bit must be set to 0.  
DIV2 is used in association with D5 (OPBITEN). This is explained further in Table 11.  
When DIV2 = '1', the MSB of the DAC data is passed directly to the VOUT pin.  
When DIV2 = '0', the MSB/2 of the DAC data is output at the VOUT pin.  
This bit must always be set to 0.  
This bit is used in association with OPBITEN (D5). The function of this bit is to control what is  
output at the VOUT pin when the on-chip DAC is connected to VOUT. This bit should be  
set to '0' if the control bit OPBITEN = '1'. This is explained further in Table 11.  
When MODE = '1', the SIN ROM is bypassed, resulting in a ramp output from the DAC.  
When MODE = '0' the SIN ROM is used to convert the phase information into amplitude infor-  
mation which results in a sinusoidal signal at the output.  
D2  
D1  
Reserved  
MODE  
D0  
Reserved  
This bit must always be set to 0.  
10–  
REV PrG  
PRELIMINARY TECHNICAL DATA  
AD9833  
The Frequency and Phase Resisters  
The AD9833 contains 2 frequency registers and 2 phase  
registers. These are described in Table 3 below.  
Table 5: Writing 3FFF0000 to FREQ0 REG  
SDATA input  
Result of input word  
Table 3. Frequency/Phase Registers  
0010 0000 0000 0000  
Control word write (D15, D14 = 00);  
B28 (D13) = 1; HLB (D12) = X  
FREQ0 REG write (D15, D14 = 01);  
14 LSBs = 0000  
FREQ0 REG write (D15, D14 = 01);  
14 MSBs = 3FFF  
Register  
Size  
Description  
0100 0000 0000 0000  
0111 1111 1111 1111  
FREQ0  
28 Bits Frequency Register 0. When the  
FSELECT bit = 0, this register  
defines the output frequency as a  
fraction of the MCLK frequency.  
28 Bits Frequency Register 1. When the  
FSELECT bit = 1, this register  
defines the output frequency as a  
fraction of the MCLK frequency.  
In some applications, the user does not need to alter all 28  
bits of the frequency register. With coarse tuning, only  
the 14 MSBs are altered while with fine tuning, only the  
14 LSBs are altered. By setting the control bit B28 (D13)  
to 0, the 28-bit frequency register operates as 2 14-bit  
registers, one containing the 14 MSBs and the other con-  
taining the 14 LSBs. This means that the 14 MSBs of the  
frequency word can be altered independent of the 14 LSBs  
and vice versa. Bit HLB (D12) in the control register  
identifies which 14 bits are being altered. Examples of this  
are shown below.  
FREQ1  
PHASE0 12 Bits Phase Offset Register 0. When the  
PSELECT bit = 0, the contents of  
this register are added to the output  
of the phase accumulator.  
PHASE1 12 Bits Phase Offset Register 1. When the  
PSELECT bit = 1, the contents of  
this register are added to the output  
of the phase accumulator.  
Table 6: Writing 3FFF to the 14 LSBs of FREQ1 REG  
SDATA input  
Result of input word  
The analog output from the AD9833 is  
f
MCLK/228 x FREQREG  
0000 0000 0000 0000 Control word write (D15, D14 = 00);  
B28 (D13) = 0; HLB (D12) = 0, i.e. LSBs  
1011 1111 1111 1111 FREQ1 REG write (D15, D14 = 10);  
14LSBs=3FFF  
where FREQREG is the value loaded into the selected  
frequency register. This signal will be phase shifted by  
2π/4096 x PHASEREG  
where PHASEREG is the value contained in the selected  
phase register.  
Table 7: Writing 3FFF to the 14 MSBs of FREQ0 REG  
The flow chart in Figure 8 shows the routine for writing  
to the frequency and phase registers of the AD9833.  
SDATA input  
Result of Input word  
0001 0000 0000 0000 Control word write (D15, D14 = 00);  
B28 (D13) = 0; HLB (D12) = 1, i.e. MSBs  
0111 1111 1111 1111 FREQ0 REG write (D15, D14 = 01);  
14 MSBs = 3FFF  
Writing to a Frequency Register:  
When writing to a frequency register, bits D15 and D14  
give the address of the frequency register.  
Table 4. Frequency Register Bits  
D15 D14  
D13  
D0  
Writing to a Phase Register:  
When writing to a phase register, bits D15 and D14 are  
set to 11. Bit D13 identifies which phase register is being  
loaded.  
0
1
1
0
MSB  
MSB  
14 FREQ0 REG BITS  
14 FREQ1 REG BITS  
LSB  
LSB  
If the user wishes to alter the entire contents of a fre-  
quency register, two consecutive writes to the same  
address must be performed, as the frequency registers are  
28 bits wide. The first write will contain the 14 LSBs  
while the second write will contain the 14 MSBs. For this  
mode of operation, the control bit B28 (D13) should be  
set to 1. An example of a 28-bit write is shown in Table 5.  
Table 8. Phase Register Bits  
D15 D14 D13  
D12 D11  
D0  
1
1
1
1
0
1
X
X
MSB  
MSB  
12PHASE0BITS  
12PHASE1BITS  
LSB  
LSB  
The RESET Function  
The RESET function resets appropriate internal registers  
to zero to provide an analog output of midscale. RESET  
does not reset the phase, frequency or control registers.  
When the AD9833 is powered up, the part should be re-  
set. To reset the AD9833, set the RESET bit to 1. To  
take the part out of reset, set the bit to 0. A signal will  
REV PrG  
11–  
PRELIMINARY TECHNICAL DATA  
AD9833  
appear at the DAC output 7 MCLK cycles after RESET is  
set to 0.  
This square wave can also be divided by 2 before being  
output. The bit DIV2 (D3) in the control register controls  
the frequency of this output from the VOUT pin.  
Table 9: Applying RESET  
Sinusoidal Output: The SIN ROM is used to convert the  
phase information from the frequency and phase registers  
into amplitude information which results in a sinusoidal  
signal at the output. To have a sinusoidal output from the  
VOUT pin, set the bit MODE (D1) = 0 and the  
OPBITEN (D5) bit to 0.  
RESET bit  
Result  
0
1
No Reset Applied  
Internal Registers Reset  
Up/Down Ramp Output: The SIN ROM can be bypassed  
so that the truncated digital output from the NCO is sent  
to the DAC. In this case, the output is no longer sinusoi-  
dal. The DAC will produce a ramp up/down function. To  
have a ramp output from the VOUT pin set the bit  
MODE (D1) = 1.  
The Sleep Function  
Sections of the AD9833 which are not in use can be pow-  
ered down to minimise power consumption. This is done  
using the Sleep Function. The parts of the chip that can  
be powered down are the Internal clock and the DAC.  
The bits required for the Sleep Function are outlined in  
Table 10.  
Note that the SLEEP12 bit must be 0 (i.e. the DAC is  
enabled) when using this pin.  
Table 10: Applying the SLEEP Function  
Table 11: Various Outputs from VOUT  
SLEEP1  
bit  
SLEEP12 Result  
bit  
OPBITEN  
bit  
MODE  
bit  
DIV2  
bit  
VOUT  
Pin  
0
0
1
1
0
1
0
1
No powerdown  
DAC Powered Down  
Internal Clock disabled  
Both the DAC powered down and  
the Internal Clock disabled  
0
0
1
1
1
0
1
0
0
1
X
X
0
1
X
Sinusoid  
Up/DownRamp  
DAC data MSB / 2  
DACdataMSB  
Reserved  
DAC Powered Down: This is useful when the AD9833 is  
used to output the MSB of the DAC data only. In this  
case, the DAC is not required so it can be powered down  
to reduce power consumption.  
Internal Clock disabled: When the internal clock of the  
AD9833 is disabled the DAC output will remain at its  
present value as the NCO is no longer accumulating. New  
frequency, phase and control words can be written to the  
part when the SLEEP1 control bit is active. The  
synchronising clock is still active which means that the  
selected frequency and phase registers can also be changed  
using the control bits. Setting the SLEEP1 bit equal to 0  
enables the MCLK. Any changes made to the registers  
while SLEEP1 was active will be seen at the output after a  
certain latency.  
The VOUT Pin  
The AD9833 offers a variety of outputs from the chip, all  
of which are available from the VOUT pin. The choice of  
outputs are:  
The MSB of the DAC data,  
A sinusoidal output or  
A ramp output.  
The bits OPBITEN (D5) and MODE (D1) in the control  
register are used to decide which output is available from  
the AD9833. This is explained further below and also in  
Table 11.  
MSB of the DAC data: The MSB of the DAC data can be  
output from the AD9833. By setting the OPBITEN (D5)  
control bit to 1, the MSB of the DAC data is available at  
the VOUT pin. This is useful as a coarse clock source.  
12–  
REV PrG  
PRELIMINARY TECHNICAL DATA  
AD9833  
APPLICATIONS  
GROUNDING AND LAYOUT  
Because of the various output options available from the  
part, the AD9833 can be configured to suit a wide variety  
of applications.  
The printed circuit board that houses the AD9833 should  
be designed so that the analog and digital sections are  
separated and confined to certain areas of the board. This  
facilitates the use of ground planes which can be separated  
easily. A minimum etch technique is generally best for  
ground planes as it gives the best shielding. Digital and  
analog ground planes should only be joined in one place.  
If the AD9833 is the only device requiring an AGND to  
DGND connection, then the ground planes should be  
connected at the AGND and DGND pins of the AD9833.  
If the AD9833 is in a system where multiple devices re-  
quire AGND to DGND connections, the connection  
should be made at one point only, a star ground point that  
should be established as close as possible to the AD9833.  
One of the areas where the AD9833 is suitable is in modu-  
lation applications. The part can be used to perform  
simple modulation such as FSK. More complex modula-  
tion schemes such as GMSK and QPSK can also be  
implemented using the AD9833.  
In an FSK application, the two frequency registers of the  
AD9833 are loaded with different values; one frequency  
will represent the space frequency while the other will  
represent the mark frequency. Using the FSELECT bit in  
the control register of the AD9833, the user can modulate  
the carrier frequency between the two values.  
The AD9833 has two phase registers; this enables the part  
to perform PSK. With phase shift keying, the carrier fre-  
quency is phase shifted, the phase being altered by an  
amount which is related to the bit stream being input to  
the modulator.  
Avoid running digital lines under the device as these will  
couple noise onto the die. The analog ground plane should  
be allowed to run under the AD9833 to avoid noise cou-  
pling. The power supply lines to the AD9833 should use  
as large a track as is possible to provide low impedance  
paths and reduce the effects of glitches on the power sup-  
ply line. Fast switching signals such as clocks should be  
shielded with digital ground to avoid radiating noise to  
other sections of the board. Avoid crossover of digital and  
analog signals. Traces on opposite sides of the board  
should run at right angles to each other. This will reduce  
the effects of feedthrough through the board. A microstrip  
technique is by far the best but is not always possible with  
a double-sided board. In this technique, the component  
side of the board is dedicated to ground planes while sig-  
nals are placed on the other side.  
The AD9833 is also suitable for signal generator applica-  
tions. Because the MSB of the DAC data is available at  
the VOUT pin, the device can be used to generate a  
square wave.  
With its low current consumption, the part is suitable for  
applications in which it can be used as a local oscillator.  
Good decoupling is important. The AD9833 should have  
supply bypassing of 0.1 µF ceramic capacitors in parallel  
with 10 µF tantalum capacitors. To achieve the best from  
the decoupling capacitors, they should be placed as close  
as possible to the device, ideally right up against the de-  
vice.  
REV PrG  
13–  
PRELIMINARY TECHNICAL DATA  
AD9833  
DATA WRITE  
See Figure 8 below  
SELECT DATA  
SOURCES  
INITIALISATION  
See Figure 7 below  
WAIT 7/8 MCLK  
CYCLES  
DAC OUTPUT  
28  
* (1+ (SIN(2p(FREQREG * F * t/2 + PHASEREG/2 )))  
MCLK  
12  
V
= V  
* 18 * R  
/R  
OUT  
REF  
LOAD SET  
YES  
CHANGE  
PSELECT?  
YES  
CHANGE PHASE?  
NO  
NO  
YES  
YES  
CHANGE  
FSELECT?  
CHANGE PHASE  
REGISTER?  
CHANGE FREQUENCY?  
NO  
YES  
NO  
CHANGE FREQ  
REGISTER?  
CHANGE DAC OUTPUT  
FROM SIN TO RAMP?  
YES  
YES  
NO  
CONTROL  
REGISTER  
WRITE  
CHANGE OUTPUT TO  
A DIGITAL SIGNAL?  
YES  
(see Table 11)  
NO  
Figure 6. Flow Chart for AD9833 Initialisation and Operation  
INITIALISATION  
APPLY RESET  
(CONTROL REGISTER WRITE)  
RESET = 1  
WRITETO FREQUENCY AND PHASE REGISTERS  
28  
FREQ0 REG = F  
FREQ1 REG = F  
/ f  
* 2  
* 2  
OUT0 MCLK  
28  
/ f  
OUT1 MCLK  
12  
PHASE 0 & PHASE1 REG = (PhaseShift * 2 ) / 2p  
(See Figure 8)  
SET RESET = 0  
SELECT FREQUENCY REGISTERS  
SELECT PHASE REGISTERS  
(CONTROL REGISTER WRITE)  
RESET bit = 0  
FSELECT = Selected Freq Register  
PSELECT = Selected Phase Register  
Figure 7. Initialisation  
14–  
REV PrG  
PRELIMINARY TECHNICAL DATA  
AD9833  
DATA WRITE  
NO  
NO  
WRITE TO PHASE  
REGISTER?  
WRITE 14 MSBs OR LSBs  
WRITE A FULL 28-BIT WORD  
TO A FREQUENCY REGISTER?  
TO A FREQUENCY REGISTER?  
YES  
YES  
YES  
(CONTROL REGISTER WRITE)  
(CONTROL REGISTER WRITE)  
B28 (D13) = 1  
B28 (D13) = 0  
HLB (D12) = 0 / 1  
(16 - Bit Write)  
D15, D14 = 11  
D13 = 0/1 (chooses the  
phase register)  
WRITE 2 CONSECUTIVE  
16-BIT WORDS  
D12 = X  
D11 ... D0 = Phase Data  
WRITE A 16-BIT WORD  
(See Tables 6 & 7 for  
examples)  
(See Table 5 for Example)  
WRITE TO ANOTHER  
PHASE REGISTER?  
WRITE 14 MSBs OR LSBs  
TO A  
FREQUENCY REGISTER?  
WRITE ANOTHER FULL  
28 BITS TO A  
FREQUENCY REGISTER?  
YES  
YES  
YES  
NO  
NO  
NO  
Figure 8. Data Writes  
ister after the SPORT has been enabled. The data is  
clocked out on each rising edge of the serial clock and  
clocked into the AD9833 on the SCLK falling edge.  
INTERFACING TO MICROPROCESSORS  
The AD9833 has a standard serial interface which allows  
the part to interface directly with several microprocessors.  
The device uses an external serial clock to write the data/  
control information into the device. The serial clock can  
have a frequency of 40 MHz maximum. The serial clock  
can be continuous or, it can idle high or low between  
write operations. When data/control information is being  
written to the AD9833, FSYNC is taken low and is held  
low while the 16 bits of data are being written into the  
AD9833. The FSYNC signal frames the 16 bits of infor-  
mation being loaded into the AD9833.  
ADSP-2101/  
ADSP-2103*  
AD9833*  
TFS  
DT  
FSYNC  
SDATA  
SCLK  
SCLK  
* ADDITIONAL PINS OMITTED FOR CLARITY  
AD9833 to ADSP-21xx Interface  
Figure 9 shows the serial interface between the AD9833  
and the ADSP-21xx. The ADSP-21xx should be set up to  
operate in the SPORT Transmit Alternate Framing Mode  
(TFSW = 1). The ADSP-21xx is programmed through  
the SPORT control register and should be configured as  
follows:  
Internal clock operation (ISCLK = 1)  
Active low framing (INVTFS = 1)  
16-bit word length (SLEN = 15)  
Internal frame sync signal (ITFS = 1)  
Figure 9. ADSP2101/ADSP2103 to AD9833 Interface  
AD9833 to 68HC11/68L11 Interface  
Figure 10 shows the serial interface between the AD9833  
and the 68HC11/68L11 microcontroller. The  
microcontroller is configured as the master by setting bit  
MSTR in the SPCR to 1 and, this provides a serial clock  
on SCK while the MOSI output drives the serial data line  
SDATA. Since the microcontroller does not have a dedi-  
cated frame sync pin, the FSYNC signal is derived from a  
port line (PC7). The set up conditions for correct opera-  
tion of the interface are as follows:  
Generate a frame sync for each write (TFSR = 1).  
Transmission is initiated by writing a word to the Tx reg-  
REV PrG  
15–  
PRELIMINARY TECHNICAL DATA  
AD9833  
AD9833 to DSP56002 Interface  
SCK idles high between write operations (CPOL = 0)  
data is valid on the SCK falling edge (CPHA = 1).  
When data is being transmitted to the AD9833, the  
FSYNC line is taken low (PC7). Serial data from the  
68HC11/68L11 is transmitted in 8-bit bytes with only 8  
falling clock edges occuring in the transmit cycle. Data is  
transmitted MSB first. In order to load data into the  
AD9833, PC7 is held low after the first 8 bits are trans-  
ferred and a second serial write operation is performed to  
the AD9833. Only after the second 8 bits have been trans-  
ferred should FSYNC be taken high again.  
Figure 12 shows the interface between the AD9833 and  
the DSP56002. The DSP56002 is configured for normal  
mode asynchronous operation with a Gated internal clock  
(SYN = 0, GCK = 1, SCKD = 1). The frame sync pin is  
generated internally (SC2 = 1), the transfers are 16 bits  
wide (WL1 = 1, WL0 = 0) and the frame sync signal will  
frame the 16 bits (FSL = 0). The frame sync signal is  
available on pin SC2 but, it needs to be inverted before  
being applied to the AD9833. The interface to the  
DSP56000/DSP56001 is similar to that of the DSP56002.  
68HC11/68L11*  
DSP56002*  
AD9833*  
AD9833*  
FSYNC  
SDATA  
SC2  
STD  
FSYNC  
SDATA  
PC7  
MOSI  
SCK  
SCLK  
SCK  
SCLK  
* ADDITIONAL PINS OMITTED FOR CLARITY  
* ADDITIONAL PINS OMITTED FOR CLARITY  
Figure 10. 68HC11/68L11 to AD9833 Interface  
Figure 12. AD9833 to DSP56002 Interface  
AD9833 to 80C51/80L51 Interface  
Figure 11 shows the serial interface between the AD9833  
and the 80C51/80L51 microcontroller. The  
microcontroller is operated in mode 0 so that TXD of the  
80C51/80L51 drives SCLK of the AD9833 while RXD  
drives the serial data line SDATA. The FSYNC signal is  
again derived from a bit programmable pin on the port  
(P3.3 being used in the diagram). When data is to be  
transmitted to the AD9833, P3.3 is taken low. The  
80C51/80L51 transmits data in 8 bit bytes thus, only 8  
falling SCLK edges occur in each cycle. To load the re-  
maining 8 bits to the AD9833, P3.3 is held low after the  
first 8 bits have been transmitted and a second write op-  
eration is initiated to transmit the second byte of data.  
P3.3 is taken high following the completion of the second  
write operation. SCLK should idle high between the two  
write operations. The 80C51/80L51 outputs the serial  
data in a format which has the LSB first. The AD9833  
accepts the MSB first (the 4 MSBs being the control in-  
formation, the next 4 bits being the address while the 8  
LSBs contain the data when writing to a destination regis-  
ter). Therefore, the transmit routine of the 80C51/80L51  
must take this into account and re-arrange the bits so that  
the MSB is output first.  
AD9833 EVALUATION BOARD  
The AD9833 Evaluation Board allows designers to evalu-  
ate the high performance AD9833 DDS modulator with  
minimum of effort.  
To prove that this device will meet the user's waveform  
synthesis requirements, the user only require's a power-  
supply, an IBM-compatible PC and a spectrum analyser  
along with the evaluation board.  
The DDS evaluation kit includes a populated, tested  
AD9833 printed circuit board. The evaluation board in-  
terfaces to the parallel port of an IBM compatible PC.  
Software is available with the evaluation board which al-  
lows the user to easily program the AD9833. A schematic  
of the Evaluation board is shown in Figure 13. The soft-  
ware will run on any IBM compatible PC which has  
Microsoft Windows95, Windows98 or Windows ME 2000  
NT™ installed.  
80C51/80L51*  
AD9833*  
Using the AD9833 Evaluation Board  
The AD9833 Evaluation kit is a test system designed to  
simplify the evaluation of the AD9833. An application  
note is also available with the evaluation board and gives  
full information on operating the evaluation board.  
FSYNC  
SDATA  
P3.3  
RXD  
TXD  
SCLK  
Prototyping Area  
An area is available on the evaluation board for the user to  
add additional circuits to the evaluation test set. Users  
may want to build custom analog filters for the output or  
add buffers and operational amplifiers to be used in the  
* ADDITIONAL PINS OMITTED FOR CLARITY  
Figure 11. 80C51/80L51 to AD9833 Interface  
16–  
REV PrG  
PRELIMINARY TECHNICAL DATA  
AD9833  
final application.  
Power Supply  
XO vs. External Clock  
Power to the AD9833 Evaluation Board must be provided  
externally through pin connections. The power leads  
should be twisted to reduce ground loops.  
The AD9833 can operate with master clocks up to 25  
MHz. A 25 MHz oscillator is included on the evaluation  
board. However, this oscillator can be removed and, if  
required, an external CMOS clock connected to the part.  
VDD  
1
C11  
10mF  
2
C2  
0.1mF  
SCLK  
SDATA  
FSYNC  
DVDD  
3
J2 J3  
DVDD  
C7  
VDD  
LK1  
4
C1  
0.1mF  
5
C6  
0.1mF  
C8  
C9  
0.1mF  
C10  
10mF  
10mF  
0.1mF  
6
DVDD  
3
7
2
VDD  
C6  
0.1mF  
8
J1  
CAP  
1
9
2
4
6
18  
16  
14  
7
6
8
VDD  
SCLK  
SCLK  
SDATA  
FSYNC  
10  
11  
12  
13  
14  
15  
16  
17  
18  
19  
20  
21  
22  
23  
24  
25  
26  
27  
28  
29  
30  
31  
32  
33  
34  
35  
36  
SDATA  
FSYNC  
C3  
0.01mF  
1
COMP  
VOUT  
U1  
AD9833  
U2  
VOUT  
10  
MCLK  
LK2  
5
C4  
MCLK  
DVDD  
R1  
50R  
C5  
0.1mF  
DVDD  
DGND  
4
AGND  
U3  
OUT  
9
DGND  
Figure 13. AD9833 Evaluation Board Layout  
Integrated Circuits  
U1  
U2  
U3  
AD9833BRU  
74HCT244  
OSC XTAL 25 MHz  
Links  
Lk1 Lk2  
2 pin sil header  
Sockets  
MCLK VOUT  
Sub Minature BNC Connector  
Capacitors  
C1 C2  
C5 C6 C7 C9  
C3  
C8 C10 C11  
C4  
100nF Ceramic Capacitor 0805  
100nF Ceramic Capacitor  
10nF ceramic Capacitor  
10uF Tantalum Capacitor  
Option for extra decoupling capacitor  
Connectors  
J1  
J2, J3  
36-Pin Edge Connector  
PCB Mounting Terminal Block  
Resistor  
R1  
51 Resistor  
REV PrG  
17–  
PRELIMINARY TECHNICAL DATA  
AD9833  
OUTLINE DIMENSIONS  
Dimensionsshownininchesand(mm).  
10-Lead mSOIC Package  
(RM-10)  
0.122 (3.10)  
0.114 (2.90)  
1
0
6
5
0.199 (5.05)  
0.187 (4.75)  
0.122 (3.10)  
0.114 (2.90)  
1
PIN 1  
0.0197 (0.50) BSC  
0.120 (3.05)  
0.112 (2.85)  
0.120 (3.05)  
0.112 (2.85)  
0.037  
0.043 (1.10)  
MAX  
(0.94)  
0.031  
o
6
(0.78)  
SEATING  
PLANE  
o
0.006 (0.15)  
0.002 (0.05)  
0.012 (0.30)  
0.006 (0.15)  
0
0.028 (0.70)  
0.016 (0.40)  
0.009 (0.23)  
0.005 (0.13)  
18–  
REV PrG  

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