PRELIMINARY
FEMTOCLOCKS™ CRYSTAL-TO-LVDS
FREQUENCY SYNTHESIZER W/INTEGRATED FANOUT BUFFER
ICS844246I
GENERAL DESCRIPTION
ICS
HiPerClockS™
The ICS844246I is a Cr ystal-to-LVDS Clock
Synthesizer/Fanout Buffer designed for Fibre
Channel and Gigabit Ethernet applications and is
a member of the HiperClockS™ family of High
Performance Clock Solutions from IDT. The output
frequency can be set using the frequency select pins and a
25MHz crystal for Ethernet frequencies, or a 26.5625MHz
crystal for a Fibre Channel. The low phase noise character-
istics of the ICS844246I make it an ideal clock for these
demanding applications.
SELECT FUNCTION TABLE
Inputs
FB_SEL N_SEL1 N_SEL0
00 0
00
1
0 10
011
10
0
10
1
110
11 1
M Divide
20
20
20
20
24
24
24
24
Function
N Divide
2
4
5
8
3
4
6
12
M/N
10
5
4
2.5
8
6
4
2
FEATURES
• Six LVDS outputs
• Crystal oscillator interface
• Output frequency range: 53.125MHz to 333.3333MHz
• Crystal input frequency range: 25MHz to 33.333MHz
• RMS phase jitter at 125MHz, using a 25MHz crystal
(1.875MHz to 20MHz): 0.39ps (typical)
• Full 3.3V or 3.3V core, 2.5V output supply mode
• -40°C to 85°C ambient operating temperature
• Available in both standard (RoHS 5) and lead-free (RoHS 6)
packages
BLOCK DIAGRAM
PIN ASSIGNMENT
PLL_BYPASS Pullup
XTAL_IN
XTAL_OUT
OSC
FB_SEL Pulldown
www.DNa_taSSELh1eetP4uUllu.pcom
Pullup
N_SEL0
1
Output
PLL 0 Divider
Feedback
Divider
Q0
nQ0
Q1
nQ1
Q2
nQ2
VDDO
VDDO
nQ2
Q2
nQ1
Q1
nQ0
Q0
PLL_BYPASS
VDDA
VDD
FB_SEL
1
2
3
4
5
6
7
8
9
10
11
12
24 Q3
23 nQ3
22 Q4
21 nQ4
20 Q5
19 nQ5
18 N_SEL1
17 GND
16 GND
15 N_SEL0
14 XTAL_OUT
13 XTAL_IN
Q3 ICS844246I
nQ3 24-Lead TSSOP, E-Pad
4.40mm x 7.8mm x 0.90mm
Q4 body package
G Package
nQ4 Top View
Q5
nQ5
The Preliminary Information presented herein represents a product in pre-production. The noted characteristics are based on initial product characterization
and/or qualification. Integrated Device Technology, Incorporated (IDT) reserves the right to change any circuitry or specifications without notice.
IDT™ / ICS™ LVDS FREQUENCY SYNTHESIZER W/FANOUT BUFFER 1
ICS844246BGI REV. A NOVEMBER 14, 2007
