AD9518-1ABCPZ-RL7 Analog Devices Inc, AD9518-1ABCPZ-RL7 Datasheet - Page 29
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AD9518-1ABCPZ-RL7
Manufacturer Part Number
AD9518-1ABCPZ-RL7
Description
6-Output Clock Generator With 2.8GHz
Manufacturer
Analog Devices Inc
Type
Clock Generator, Fanout Distributionr
Datasheet
1.AD9518-1ABCPZ-RL7.pdf
(64 pages)
Specifications of AD9518-1ABCPZ-RL7
Pll
Yes
Input
CMOS, LVDS, LVPECL
Output
LVPECL
Number Of Circuits
1
Ratio - Input:output
1:6
Differential - Input:output
Yes/Yes
Frequency - Max
2.65GHz
Divider/multiplier
Yes/No
Voltage - Supply
3.135 V ~ 3.465 V
Operating Temperature
-40°C ~ 85°C
Mounting Type
Surface Mount
Package / Case
48-LFCSP
Frequency-max
2.65GHz
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
When operating the AD9518 in dual modulus mode (P//P + 1),
the equation used to relate input reference frequency to VCO
output frequency is
However, when operating the prescaler in FD mode 1, 2, or 3,
the A counter is not used (A = 0) and the equation simplifies to
When A = 0, the divide is a fixed divide of P = 2, 4, 8, 16, or 32,
in which case the previous equation also applies.
By using combinations of DM and FD modes, the AD9518
can achieve values of N all the way down to N = 1 and up to
N = 262175. Table 27 shows how a 10 MHz reference input
can be locked to any integer multiple of N.
Note that the same value of N can be derived in different ways, as
illustrated by the case of N = 12. The user can choose a fixed divide
mode of P = 2 with B = 6, use the dual modulus mode of 2/3 with
A = 0, B = 6, or use the dual modulus mode of 4/5 with A = 0,
B = 3.
A and B Counters
The B counter must be ≥3 or bypassed, and, unlike the R counter,
A = 0 is actually zero.
When the prescaler is in dual-modulus mode, the A counter
must be less than the B counter.
The maximum input frequency to the A/B counter is reflected
in the maximum prescaler output frequency (~300 MHz) that is
Table 27. Using a 10 MHz Reference Input to Generate Different VCO Frequencies
F
(MHz)
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
REF
f
f
VCO
VCO
= (f
= (f
R
1
1
1
1
1
1
1
1
1
1
1
1
1
10
1
1
10
REF
REF
/R) × (P × B + A) = f
/R) × (P × B) = f
P
1
2
1
1
1
2
2
2
2
2
8
8
16
32
8
16
32
REF
A
X
X
X
X
X
X
0
1
2
1
6
7
7
6
0
14
22
× N/R
REF
× N/R
B
1
1
3
4
5
3
3
3
3
4
18
18
9
47
25
16
84
N
1
2
3
4
5
6
6
7
8
9
150
151
151
1510
200
270
2710
Rev. A | Page 29 of 64
f
(MHz)
10
20
30
40
50
60
60
70
80
90
1500
1510
1510
1510
2000
2700
2710
VCO
specified in Table 2. This is the prescaler input frequency (VCO or
CLK) divided by P. For example, a dual modulus mode of P = 8/9
is not allowed if the VCO frequency is greater than 2400 MHz
because the frequency going to the A/B counter is too high.
When the AD9518 B counter is bypassed (B = 1), the A counter
should be set to 0, and the overall resulting divide is equal to the
prescaler setting, P. The possible divide ratios in this mode are
1, 2, 3, 4, 8, 16, and 32. This mode is useful only when an
external VCO/VCXO is used because the frequency range of the
internal VCO requires an overall feedback divider greater than 32.
Although manual reset is not normally required, the A/B counters
have their own reset bit. Alternatively, the A and B counters can be
reset using the shared reset bit of the R, A, and B counters. Note
that these reset bits are not self-clearing.
R, A, and B Counters— SYNC Pin Reset
The R, A, and B counters can also be reset simultaneously through
the SYNC pin. This function is controlled by Register 0x019[7:6]
(see
R and N Divider Delays
Both the R and N dividers feature a programmable delay cell.
These delays can be enabled to allow adjustment of the phase
relationship between the PLL reference clock and the VCO or
CLK. Each delay is controlled by three bits. The total delay
range is about 1 ns. See Register 0x019 in Table 44.
Table 44
Mode
FD
FD
FD
FD
FD
FD
DM
DM
DM
DM
DM
DM
DM
DM
DM
DM
DM
). The
SYNC pin reset is disabled by default.
Comments/Conditions
P = 1, B = 1 (A and B counters are bypassed).
P = 2, B = 1 (A and B counters are bypassed).
A counter is bypassed.
A counter is bypassed.
A counter is bypassed.
A counter is bypassed.
P = 8 is not allowed (2700 ÷ 8 > 300 MHz).
P = 32 is not allowed (A > B is not allowed).
P = 32, A = 22, B = 84.
P = 16 is also permitted.
AD9518-1