Analog Devices AD9520-0, Руководство пользователя

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UG-076 Evaluation Board User Guide
Rev. A | Page 6 of 16
7. Program the R (reference) divider by clicking the
R DIVIDER
box at the top of the main window.
Set the desired value and click OK (see Figure 13).
8. 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.
9. 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 click OK .
10. Note that if the desired configuration has the a 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.
11. 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.
12. Power down unused drivers by clicking the numbered
triangular symbol (see Figure 7) on the right side of the
main window, and then clicking
Safe Power Down .
0
8746-
026
Figure 7. Driver Symbol
13. Set the channel dividers by clicking DIVIDER 0 through
DIVIDER 3 , and entering the divider ratio.
14. Click the flashing red WRITE button under the REGISTER
W/R section. This loads the desired settings to the AD9520
evaluation board.
15. Click the blinking yellow Cal VCO button to open 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 is now locked and the lock detect (LD)
LED on the left side of the board is on.