AD9516-1/PCBZ View Datasheet(PDF) - Analog Devices
Part Name
Description
MFG CO.
'AD9516-1/PCBZ' PDF : 84 Pages View PDF
Data Sheet
Clock Distribution or External VCO < 1600 MHz
When the external clock source to be distributed or the external
VCO/VCXO is less than 1600 MHz, a configuration that bypasses
the VCO divider can be used. This configuration differs from the
High Frequency Clock Distribution—CLK or External VCO >
1600 MHz section only in that the VCO divider (divide-by-2,
divide-by-3, divide-by-4, divide-by-5, and divide-by-6) is
bypassed. This limits the frequency of the clock source to
<1600 MHz (due to the maximum input frequency allowed at the
channel dividers).
Configuration and Register Settings
For clock distribution applications where the external clock is
<1600 MHz, use the register settings that are shown in Table 25.
Table 25. Settings for Clock Distribution < 1600 MHz
Register
Function
0x010[1:0] = 01b
PLL asynchronous power-down (PLL off )
0x1E1[0] = 1b
Bypass the VCO divider as source for
distribution section
0x1E1[1] = 0b
CLK selected as the source
AD9516-1
When using the internal PLL with an external VCO of <1600 MHz,
the PLL must be turned on.
Table 26. Settings for Using Internal PLL with External VCO <
1600 MHz
Register
Function
0x1E1[0] = 1b
Bypass the VCO divider as source for
distribution section
0x010[1:0] = 00b
PLL normal operation (PLL on), along with
other appropriate PLL settings in Register 0x010
to Register 0x01E
An external VCO/VCXO requires an external loop filter that
must be connected between CP and the tuning pin of the
VCO/VCXO. This loop filter determines the loop bandwidth
and stability of the PLL. Make sure to select the proper PFD
polarity for the VCO/VCXO being used.
Table 27. Setting the PFD Polarity
Register
Function
0x010[7] = 0b
PFD polarity positive (higher control voltage
produces higher frequency)
0x010[7] = 1b
PFD polarity negative (higher control voltage
produces lower frequency)
After the appropriate register values are programmed,
Register 0x232 must be set to 0x01 for the values to take effect.
Rev. C | Page 31 of 80
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