
FEMTOCLOCKS CRYSTAL-TO-HCSL
CLOCK GENERATOR
ICS841602I
IDT / ICS HCSL CLOCK GENERATOR
1
ICS841602AGI REV. A JULY 10, 2008
GENERAL DESCRIPTION
The ICS841602I is an optimized PCIe and
sRIO clock generator and member of the
HiPerClocks family of high-performance clock
solutions from IDT. The device uses a 25MHz
parallel crystal to generate 100MHz and 125MHz
clock signals, replacing solutions requiring multiple oscilla-
tor and fanout buffer solutions. The device has excellent
phase jitter (< 1ps rms) suitable to clock components requiring
precise and low-jitter PCIe or sRIO or both clock signals.
Designed for telecom, networ king and industr ial appli-
cations, the ICS841602I can also drive the high-speed sRIO
and PCIe SerDes clock inputs of communication processors,
DSPs, switches and bridges.
FEATURES
Two differential clock outputs: configurable for PCIe (100MHz)
and sRIO (125MHz) clock signals
Selectable crystal oscillator interface, 25MHz, 18pF parallel
resonant crystal or LVCMOS/LVTTL single-ended reference
clock input
Supports the following output frequencies:
100MHz or 125MHz
VCO: 500MHz
PLL bypass and output enable
PCI Express (2.5Gb/s) and Gen 2 (5 Gb/s) jitter compliant
RMS phase jitter, 125MHz, using a 25MHz crystal:
(1.875MHz – 20MHz): 0.45ps (typical)
Full 3.3V power supply mode
-40°C to 85°C ambient operating temperature
Available in both standard (RoHS 5) and lead-free (RoHS 6)
packages
HiPerClockS
ICS
BLOCK DIAGRAM
0
1
0
M = ÷20
OSC
FemtoClock
PLL
VCO = 500MHz
÷N
÷4
÷5 (default)
XTAL_IN
XTAL_OUT
REF_SEL
FSEL
MR/nOE
IREF
BYPASS
REF_IN Pulldown
Pulldown
Q0
nQ0
Q1
nQ1
PIN ASSIGNMENT
1
2
3
4
5
6
7
8
9
10
11
12
13
14
28
27
26
25
24
23
22
21
20
19
18
17
16
15
ICS841602I
28-Lead TSSOP
6.1mm x 9.7mm x 0.925mm
package body
G Package
Top View
REF_SEL
REF_IN
VDD
GND
XTAL_IN
XTAL_OUT
MR/nOE
VDD
nc
GND
VDD
VDDA
BYPASS
IREF
FSEL
VDD
nQ1
Q1
nQ0
Q0
GND
nc