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⋅
Sync_NCO:
⋅
Phstr Clk Div Selects the clock used to latch the PHSTR input when restarting the
Select:
⋅
DAC Serial
Data:
⋅
NCO:
⋅
QMC:
⋅
Mode:
⋅
PLL Divider:
⋅
Interpolation: Sets FIR Interpolation factor: {X2, X4, X4L, X8}. X4 uses lower power than
⋅
Phstr Init.
Phase:
⋅
Sync FIFO:
⋅
Alt.
PLLLOCK
Output:
SLWU017B – APRIL 2005 – Revised March 2007
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When set, the NCO phase accumulator is cleared with a phstr low to high
transition.
internal clock dividers. When set, the full rate CLK2 signal latches PHSTR.
When cleared, the divided down input clock signal latches PHSTR.
When set, both DAC A and DAC B input data is replaced with fixed data
loaded into the 16 bit serial interface DAC Static Data.
o
Counter Mode: Controls the internal counter that can be used as the DAC
data source. See the data sheet for more information.
o
DAC Static Data: When DAC Serial Data is set, both DAC A and DAC B
input data is replaced with fixed data loaded with this value. Range = 0 to
65535.
When set, enables NCO.
o
NCO Gain: Sets NCO gain resulting in a 2x increase in NCO output
amplitude. Except for F
selection can result in saturation for full scale inputs. Consider using QMC
gain for lower gains.
When set, enables the QMC.
o
QMCA Gain: Sets QMC gain A to a range = 0 to 2047. See the data
sheet for more information.
o
QMC B Gain: Sets QMC gain B to a range = 0 to 2047. See the data
sheet for more information.
o
QMC Phase: Sets QMC phase to a range = -512 to 511. See the data
sheet for more information.
Used to select the coarse mixer mode. See the DAC5687 data sheet for
more information.
Sets VCO divider to div by 1, 2, 4, or 8.
4xL, but F
= 320 MSPS max when NCO or QMC are used.
DAC
Adjusts the initial phase of the F
Sync source selection mode for the FIFO. When a low to high transition is
detected on the selected sync source, the FIFO input and output pointers
are initialized. See the DAC5687 data sheet for source description.
Sets PLLLOCK output pin to F
mode. Settings must be used in conjunction with the interpolation setting
to achieved desired rate (i.e. set to F
F
/4 for 4x interpolation). Note, there is no option for the 8x mode. The
DAC
jumper at W1 (EXTLO) must be removed to utilize this functionality.
DAC5687 EVM Operational Procedure
/2 and F
/4 mixing NCO frequencies, this
S
S
/2 and F
/4 cmix block at PHSTR.
S
S
frequency when operating in the PLL
DAC
/2 for 2x interpolation, set to
DAC
DAC5687 EVM
15
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