AD9953-PCB Analog Devices, Inc., AD9953-PCB Datasheet - Page 16

• Manufacturer Part Number: AD9953-PCB
• Description: 400 Msps 14-bit, 1.8v Cmos Direct Digital Synthesizer
• Manufacturer: Analog Devices, Inc.

AD9953
Control Register Bit Descriptions
Control Function Register. No. 1 (CFR1)
The CFR1 is used to control the various functions, features, and
modes of the AD9953. The functionality of each bit is below.
CFR1<31>: RAM Enable Bit
CFR1<31> = 0 (default). The RAM is powered down to con-
serve power. Single-tone mode of operation is active.
CFR1<31> = 1. If CFR1<31> is active, the RAM is enabled for
operation. Access control for normal operation is controlled via
the mode control bits of the RSCW for the current profile.
CFR1<30>: RAM Destination Bit
CFR1<30> = 0 (default). If CFR1<31> is active, a Logic 0 on the
RAM destination bit (CFR1<30> = 0) configures the AD9953
such that the RAM output drives the phase accumulator (i.e.,
the frequency tuning word). If CFR1<31> is inactive,
CFR1<30> is a Don’t Care.
CFR1<30> = 1. If CFR1<31> is active, a Logic 1 on the RAM
destination bit (CFR1<30> = 1) configures the AD9953 such
that the RAM output drives the phase-offset adder (i.e., sets the
phase offset of the DDS core).
CFR1<29:27>: Not Used
CFR1<26>: Amplitude Ramp Rate Load Control Bit
CFR1<26> = 0 (default). The amplitude ramp rate timer is
loaded only upon timeout (timer == 1) and is not loaded due to
an I/O UPDATE input signal.
CFR1<26> = 1. The amplitude ramp rate timer is loaded upon
timeout (timer == 1) or at the time of an I/O UPDATE input signal.
CFR1<25>: Shaped On-Off Keying Enable Bit
CFR1<25> = 0 (default). Shaped on-off keying is bypassed.
CFR1<25> = 1. Shaped on-off keying is enabled. When enabled,
CFR1<24> controls the mode of operation for this function.
CFR1<24>: Auto Shaped On-Off Keying Enable Bit (Only Valid
when CFR1<25> Is Active High)
CFR1<24> = 0 (default). When CFR1<25> is active, a Logic 0
on CFR1<24> enables the manual shaped on-off keying opera-
tion. Each amplitude sample sent to the DAC is multiplied by
the amplitude scale factor. See the Shaped On-Off Keying sec-
tion for details.
CFR1<24> = 1. When CFR1<25> is active, a Logic 1 on
CFR1<24> enables the auto shaped on-off keying operation.
Toggling the OSK pin high will cause the output scalar to ramp
up from zero scale to the amplitude scale factor at a rate deter-
mined by the amplitude ramp rate. Toggling the OSK pin low
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will cause the output to ramp down from the amplitude scale
factor to zero scale at the amplitude ramp rate. See the Shaped
On-Off Keying section for details.
CFR1<23>: Automatic Synchronization Enable Bit
CFR1<23> = 0 (default). The automatic synchronization feature
of multiple AD9953s is inactive.
CFR1<23> = 1. The automatic synchronization feature of mul-
tiple AD9953s is active. The device will synchronize its internal
synchronization clock (SYNC_CLK) to align to the signal pre-
sent on the SYNC_IN input. See the Synchronizing Multiple
AD9953s section for details.
CFR1<22>: Software Manual Synchronization of Multiple
AD9953s
CFR1<22> = 0 (default). The manual synchronization feature is
inactive.
CFR1<22> = 1. The software controlled manual synchroniza-
tion feature is executed. The SYNC_CLK rising edge is
advanced by one SYNC_CLK cycle and this bit is cleared. To
advance the rising edge multiple times, this bit needs to be set
for each advance. See the Synchronizing Multiple AD9953s sec-
tion for details.
CFR1<21:14>: Not Used
CFR1<13>: Auto-Clear Phase Accumulator Bit
CFR1<13> = 0 (default). The current state of the phase accumula-
tor remains unchanged when the frequency tuning word is applied.
CFR1<13> = 1. This bit automatically synchronously clears
(loads 0s into) the phase accumulator for one cycle upon recep-
tion of an I/O UPDATE signal.
CFR1<12>: Sine/Cosine Select Bit
CFR1<12> = 0 (default). The angle-to-amplitude conversion
logic employs a COSINE function.
CFR1<12> = 1. The angle-to-amplitude conversion logic
employs a SINE function.
CFR1<11>: Not Used
CFR1<10>: Clear Phase Accumulator
CFR1<10> = 0 (default). The phase accumulator functions as
normal.
CFR1<10> = 1. The phase accumulator memory elements are
cleared and held clear until this bit is cleared.
CFR1<9>: SDIO Input Only