
FEMTOCLOCKS CRYSTAL-TO-LVDS
FREQUENCY SYNTHESIZER
ICS844002
IDT / ICS LVDS FREQUENCY SYNTHESIZER
1
ICS844002AG REV. B JULY 25, 2008
GENERAL DESCRIPTION
The ICS844002 is a 2 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 ICS844002 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 ICS844002 is packaged in a small 20-pin TSSOP package.
FEATURES
Two 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 @ 212.5MHz, using a 26.5625MHz crystal
(637kHz - 10MHz): 0.65ps (typical)
Full 3.3V or 2.5V supply modes
0°C to 70°C ambient operating temperature
Available in both standard (RoHS 5) and lead-free (RoHS 6)
packages
HiPerClockS
ICS
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
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FREQUENCY SELECT FUNCTION TABLE
F_SEL[1:0]
nPLL_SEL
REF_CLK
XTAL_IN
XTAL_OUT
nXTAL_SEL
MR
Q0
nQ0
Q1
nQ1
Pulldown
26.5625MHz
Pulldown
ICS844002
20-Lead TSSOP
6.5mm x 4.4mm x 0.925mm
package body
G Package
Top View
nc
VDDO
Q0
nQ0
MR
nPLL_SEL
nc
VDDA
F_SEL0
VDD
1
2
3
4
5
6
7
8
9
10
20
19
18
17
16
15
14
13
12
11
VDDO
Q1
nQ1
GND
nc
nXTAL_SEL
REF_CLK
XTAL_IN
XTAL_OUT
F_SEL1
PIN ASSIGNMENT