Analog Devices AD9522 Series, Руководство пользователя

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UG-077 Evaluation Board User Guide
Rev. 0 | Page 6 of 16
6. Program the R (reference) divider by clicking the R DIVIDER
box at the top of the main window. Set the desired value
(72, in this case) and click
OK (see Figure 13).
7. Program the N (feedback) divider by clicking the N
DIVIDER box at the top of the main window. Set the
desired value and click OK . For this example, N = 5500
can use 8/9 dual modulus mode with A = 4 and B = 687.
8. Set the charge pump current (1.2 mA in this case) by
clicking the
CHARGE PUMP box in the upper right
corner of the main window, and then click OK .
9. Note that if the desired configuration has the phase
detector frequency above 50 MHz, an antibacklash pulse
width of 1.3 ns may work better. This setting is accessed by
clicking the
PFD box to the left of the CHARGE PUMP
box. However, this setting normally does not need to be
modified.
10. Set the VCO divider by clicking the green
VCO
box in the
center of the main window, immediately to the left of the
Cal VCO button.
11. Power down unused drivers by clicking the numbered
triangular symbol on the right side of the main window
(see Figure 7), and then clicking
Power Down (Off) in the
output driver window (see Figure 21 ) . Unused drivers that
are not powered down can be a source of unwanted noise
in the output signals.
08
74
7-
0
07
Figure 7. Driver Symbol
12. Set the channel dividers by clicking DIVIDER 0 through
DIVIDER 3 , and entering the divider ratio.
13. Click the flashing red WRITE button under the REGISTER
W/R control section. This loads the desired settings to the
AD9522 evaluation board.
14. Click the blinking yellow Cal VCO button to load the VCO
calibration window. The default VCO divide ratio (16)
works for all applications. Click the
Cal VCO button in the
Calibrate VCO window to begin calibration (see Figure 19).
The PLL should now be locked and the
LD
(lock detect)
LED on the left side of the board should be on.