
FEMTOCLOCKS 1:5, CRYSTAL-TO-
LVCMOS/LVTTL FREQUENCY SYNTHESIZER
ICS840245I
IDT / ICS LVCMOS/LVTTL FREQUENCY SYNTHESIZER
1
ICS840245AGI REV. B NOVEMBER 16, 2006
GENERAL DESCRIPTION
The ICS840245I is a low skew, 1-to-5 LVCMOS/
LVTTL SATA/SAS Clock Generator and is a mem-
ber of the HiPerClocksTM family of high performance
clock solutions from IDT. The ICS840245I can syn-
thesize 75MHz reference clock frequencies with a
25MHz crystal. Each of the 5 outputs on the ICS840245I can
drive two series terminated 50
transmission lines, effectively
making the ICS840245I a 1-to-10 clock generator. An output
enable (OE) pin, which controls only the Q4 output, allows the
application to use Q4 as an optional output (for example, test
output pin). The ICS840245I uses IDT’s 3rd generation low phase
noise VCO technology and can achieve 1ps or lower typical
random rms phase jitter. The ICS840245I is packaged in a
16-pin TSSOP package.
HiPerClockS
ICS
BLOCK DIAGRAM
PIN ASSIGNMENT
XTAL_OUT
XTAL_IN
VDDA
OE
VDD
GND
PLL_SEL
GND
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
VDDO
Q0
Q1
GND
Q2
Q3
VDDO
Q4
ICS840245I
16-Lead TSSOP
4.4mm x 5.0mm x 0.92mm
package body
G Package
Top View
FEATURES
Five LVCMOS outputs, 15
typical output impedance
Crystal oscillator interface
Supports the following output frequency: 75MHz
Output skew: 25ps (typical)
RMS phase jitter @ 75MHz (900kHz - 7.5MHz):
0.454ps (typical)
Output supply modes:
Core/Output
3.3V/3.3V
3.3V/2.5V
2.5V/2.5V
-40°C to 85°C ambient operating temperature
Available in both standard (RoHS 5) and lead-free (RoHS 6)
packages
0
1
N = 8
VCO
600MHz
Phase
Detector
OSC
M = 24
(fixed)
PLL_SEL
OE
XTAL_IN
XTAL_OUT
25MHz
Pullup
Q0
Q1
Q2
Q3
Q4