AD9511/PCB Analog Devices Inc, AD9511/PCB Datasheet - Page 30

• Manufacturer Part Number: AD9511/PCB
• Description: BOARD EVAL CLOCK DISTR 48LFCSP
• Manufacturer: Analog Devices Inc
• Type: Clock Distributionr

Specifications of AD9511/PCB

• Contents: Evaluation Board
• For Use With/related Products: AD9511
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

AD9511
Table 14. PLL Prescaler Modes
Mode
(FD = Fixed Divide
DM = Dual Modulus)
FD
FD
P = 2 DM
P = 4 DM
P = 8 DM
P = 16 DM
P = 32 DM
FD
When using the prescaler in FD mode, the A counter is not
used, and the B counter may need to be bypassed. The DM
prescaler modes set some upper limits on the frequency, which
can be applied to CLK2. See Table 15.
Table 15. Frequency Limits of Each Prescaler Mode
Mode (DM = Dual Modulus)
P = 2 DM (2/3)
P = 4 DM (4/5)
P = 8 DM (8/9)
P = 16 DM
P = 32 DM
Table 16. P, A, B, R—Smallest Values for N
F
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
REF
R
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
P
1
2
1
1
1
2
2
2
2
2
2
2
2
2
2
4
4
000
001
010
011
100
101
110
111
Value in 0Ah<4:2>
A
X
X
X
X
X
X
0
1
2
1
X
0
1
X
0
0
1
B
1
1
3
4
5
3
3
3
3
4
5
5
5
6
6
3
3
CLK2
<600 MHz
<1000 MHz
<1600 MHz
<1600 MHz
<1600 MHz
N
1
2
3
4
5
6
6
7
8
9
10
10
11
12
12
12
13
Divide By
1
2
P/P + 1 = 2/3
P/P + 1 = 4/5
P/P + 1 = 8/9
P/P + 1 = 16/17
P/P + 1 = 32/33
3
F
10
20
30
40
50
60
60
70
80
90
100
100
110
120
120
120
130
VCO
Rev. A | Page 30 of 60
Mode
FD
FD
FD
FD
FD
FD
DM
DM
DM
DM
FD
DM
DM
FD
DM
DM
DM
A and B Counters
The AD9511 B counter has a bypass mode (B = 1), which is not
available on the ADF4106. The B counter bypass mode is valid
only when using the prescaler in FD mode. The B counter is
bypassed by writing 1 to the B counter bypass bit (0Ah<6> =
1b). The valid range of the B counter is 3 to 8191. The default
after a reset is 0, which is invalid.
Note that the A counter is not used when the prescaler is in
FD mode.
Note also that the A/B counters have their own reset bit,
which is primarily intended for testing. The A and B counters
can also be reset using the R, A, and B counters’ shared reset bit
(09h<0>).
Determining Values for P, A, B, and R
When operating the AD9511 in a dual-modulus mode, the
input reference frequency, F
frequency, F
When operating the prescaler in fixed divide mode, the A
counter is not used and the equation simplifies to
By using combinations of dual modulus and fixed divide
modes, the AD9511 can achieve values of N all the way down to
N = 1. Table 16 shows how a 10 MHz reference input may be
locked to any integer multiple of N. Note that the same value of
N may be derived in different ways, as illustrated by N = 12.
F
F
VCO
VCO
= (F
= (F
VCO.
REF
REF
/R) × (PB + A) = F
/R) × (PB) = F
Notes
P = 1, B = 1 (Bypassed)
P = 2, B = 1 (Bypassed)
P = 1, B = 3
P = 1, B = 4
P = 1, B = 5
P = 2, B = 3
P/P + 1 = 2/3, A = 0, B = 3
P/P + 1 = 2/3, A = 1, B = 3
P/P + 1 = 2/3, A = 2, B = 3
P/P + 1 = 2/3, A = 1, B = 4
P = 2, B = 5
P/P + 1 = 2/3, A = 0, B = 5
P/P + 1 = 2/3, A = 1, B = 5
P = 2, B = 6
P/P + 1 = 2/3, A = 0, B = 6
P/P + 1 = 4/5, A = 0, B = 3
P/P + 1 = 4/5, A = 1, B = 3
REF
, is related to the VCO output
REF
× N/R
REF
× N/R