
FEMTOCLOCKS CRYSTAL-TO-LVDS
FREQUENCY SYNTHESIZER
ICS844004-104
IDT / ICS LVDS FREQUENCY SYNTHESIZER
1
ICS844004AK-104 REV. A SEPTEMBER 15, 2008
General Description
The ICS844004-104 is a 4 output LVDS Synthesizer
optimized to generate Fibre Channel reference clock
frequencies and is a member of the HiPerClocksTM
family of high performance clock solutions from IDT.
Using a 26.5625MHz 18pF parallel resonant crystal,
the following frequencies can be generated based on the 2
frequency select pins (F_SEL[1:0]): 212.5MHz, 187.5MHz,
159.375MHz, 106.25MHz and 53.125MHz. The ICS844004-104
uses IDT’s 3rd generation low phase noise VCO technology and
can achieve <1ps typical rms phase jitter, easily meeting Fibre
Channel jitter requirements. The ICS844004-104 is packaged in a
32-pin VFQFN package.
Features
Four differential LVDS outputs
Selectable crystal oscillator interface or LVCMOS/LVTTL
single-ended input
Supports the following output frequencies: 212.5MHz,
187.5MHz, 159.375MHz, 106.25MHz and 53.125MHz
VCO range: 560MHz - 680MHz
RMS phase jitter at 212.5MHz (637kHz – 10MHz), using a
26.5625MHz crystal: <1ps (typical)
Full 3.3V or 2.5V output supply modes
0°C to 70°C ambient operating temperature
Available in both standard (RoHS 5) and lead-free (RoHS 6)
packages
Table 1. Frequency Table
HiPerClockS
ICS
Inputs
Output
Frequency
(MHz)
Input
Frequency
(MHz)
F_SEL1
F_SEL0
M
Divider
Value
N
Divider
Value
M/N
Divider
Value
26.5625
0
24
3
8
212.5
(default)
26.5625
0
1
24
4
6
159.375
26.5625
1
0
24
6
4
106.25
26.5625
1
24
12
2
53.125
23.4375
0
24
3
8
187.5
(default)
1
0
1
0
Phase
Detector
VCO
637.5MHz
(w/26.5625MHz
Reference)
M = 24 (fixed)
F_SEL[1:0]
0 0
÷3
0 1
÷4
1 0
÷6
1 1
÷12
2
OSC
F_SEL[1:0]
nPLL_SEL
nXTAL_SEL
MR
REF_CLK
XTAL_IN
XTAL_OUT
Q0
nQ0
Q1
nQ1
Q2
nQ2
Q3
nQ3
Pulldown
26.5625MHz
9
10 11 12 13 14 15 16
32 31 30
29 28
27 26 25
1
2
3
4
5
6
7
8
24
23
22
21
20
19
18
17
Q0
nQ0
MR
nPLL_SEL
nc
Q3
nQ3
GND
nc
nXTAL_SEL
REF_CLK
GND
V
DDA
F_SEL0
V
DD
F_SEL1
XTAL_OUT
XTAL_IN
nc
Q1
nQ1
nc
nQ2
Q2
V
DDO
V
DDO
Block Diagram
Pin Assignment
ICS844004-104
32 Lead VFQFN
5mm x 5mm x 0.925mm
package body
K Package
Top View