ICS844256 Datasheet, PDF (1/16 Pages) Integrated Circuit Systems – FEMTOCLOCKS™ CRYSTAL-TO-LVDS FREQUENCY SYNTHESIZER W/INTEGRATED FANOUT BUFFER

PRELIMINARY
FEMTOCLOCKS™ CRYSTAL-TO-LVDS
FREQUENCY SYNTHESIZER W/INTEGRATED FANOUT BUFFER
ICS844256
GENERAL DESCRIPTION
ICS
The ICS844256 is a Cr ystal-to-LVDS Clock
Synthesizer/Fanout Buffer designed for SONET
HiPerClockS™ _{a n d G i g a b i t E t h e r n e t a p p l i c a t i o n s a n d i s a}
member of the HiperClockS™ family of High
Perfor mance Clock Solutions from IDT. The
output frequency can be set using the frequency select
pins and a 25MHz crystal for Ethernet frequencies, or a
19.44MHz crystal for SONET. The low phase noise character-
istics of the ICS844256 make it an ideal clock for these
demanding applications.
SELECT FUNCTION TABLE
Inputs
FB_SEL N_SEL1 N_SEL0
0
0
0
0
0
1
0
1
0
0
1
1
1
0
0
1
0
1
1
1
0
1
1
1
M Divide
25
25
25
25
32
32
32
32
Function
N Divide
1
2
4
5
1
2
4
8
M/N
25
12.5
6.25
5
32
16
8
4
FEATURES
• Six LVDS outputs
• Crystal oscillator interface
• Output frequency range: 62.5MHz to 622.08MHz
• Crystal input frequency range: 15.625MHz to 25.5MHz
• RMS phase jitter at 125MHz, using a 25MHz crystal
(1.875MHz to 20MHz): 0.48ps (typical)
• Full 3.3V or 3.3V core, 2.5V output supply mode
• 0°C to 70°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
N_SEL1 ^Pullup
N_SEL0 ^Pullup
1
Output
Divider
PLL
0
Feedback
Divider
Q0
nQ0
Q1
nQ1
Q2
nQ2
VDDO 1
VDDO 2
nQ2 3
Q2 4
nQ1 5
Q1 6
nQ0 7
Q0 8
PLL_BYPASS 9
VDDA 10
VDD 11
FB_SEL 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
ICS844256
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
ICS844256BG REV. B NOVEMBER 19, 2007