EVAL-AD9837SDZ Analog Devices Inc, EVAL-AD9837SDZ Datasheet - Page 6

• Manufacturer Part Number: EVAL-AD9837SDZ
• Description: EVALUATION BOARD
• Manufacturer: Analog Devices Inc
• Series: -r

Specifications of EVAL-AD9837SDZ

• Main Purpose: Timing, Direct Digital Synthesis (DDS)
• Embedded: No
• Utilized Ic / Part: AD9837
• Primary Attributes: -
• Secondary Attributes: Graphical User Interface
• Kit Application Type: Clock & Timing
• Application Sub Type: Clock Generator
• Kit Contents: Software CD, USB Cable
• Silicon Manufacturer: Analog Devices
• Silicon Core Number: AD9837
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

UG-269
SELECT EXTERNAL MCLK FREQUENCY
Having selected the digital interface specifics, next use the
EXTERNAL MCLK box to choose which frequency to use. The
boards are supplied with a 75 MHz general oscillator. If a different
clock source is required, the CLK1 SMB connector can be used
to supply a different MCLK value.
Two options for the general oscillator include the AEL3013
oscillators from AEL Crystals and the SG-310SCN oscillators
from Epson Electronics.
LOADING FREQUENCY AND PHASE REGISTERS
The desired output frequency and output phase can be loaded
using the inputs shown in Figure 7. Either the FREQ 0 register or
the FREQ 1 register can be loaded with frequency data. The
frequency data is loaded in megahertz, and the equivalent hex code
is shown to the right once data is entered; click Enter to load
data. Once data is loaded, the output appears on the IOUT1 and
IOUT2 pins. Similarly, either the PHASE 0 register or PHASE 1
register can be selected, and the phase data is loaded in degrees.
The analog output frequency from the
where FREQREG is the value loaded into the selected frequency
register in decimals. This signal is phase shifted by
where PHASEREG is the value contained in the selected phase
register in decimals.
f
2π/4096 × PHASEREG
MCLK
/2
28
× FREQREG
Figure 7. Frequency and Phase Load
Figure 6. EXTERNAL MCLK Input
AD9837
is defined by
Rev. 0 | Page 6 of 12
FSK AND PSK FUNCTIONALITY
In software mode, the AD9837 can be set up for FSK or PSK
functionality by simply entering the bit rate in milliseconds
and selecting the push-button option (see Figure 8).
WAVEFORM OPTIONS
The output waveform can be selected as a sinusoidal waveform
or a ramp waveform. The internal comparator in the AD9837
can be disabled or enabled (see Figure 9). The MSB or the
MSB/2 of the phase accumulator can be selected as the output
on the SIGN BIT OUT pin.
Power-Down Options
The AD9837 has various power-down options selected through
the control register. The part can disable the MCLK or disable
the DAC if just the MSB output is used on the SIGN BIT OUT
pin, or it can power down both sections for a lower power sleep
mode (see Figure 10).
Figure 9. Waveform Profile and SIGN BIT OUT Pin
Figure 8. FSK and PSK Functionality
Evaluation Board User Guide
Figure 10. Power-Down Options