PRELIMINARY
FEMTOCLOCKS™ CRYSTAL-TO-LVDS
FREQUENCY SYNTHESIZER
ICS844004
GENERAL DESCRIPTION
FEATURES
The ICS844004 is a 4 output LVDS Synthesizer
• Four LVDS outputs
ICS
HiPerClockS™
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
• Selectable crystal oscillator interface
or LVCMOS/LVTTL single-ended input
• Supports the following output frequencies: 212.5MHz,
187.5MHz, 159.375MHz, 156.25MHz, 106.25MHz,
53.125MHz
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, 156.25MHz, 106.25MHz
and 53.125MHz. The ICS844004 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 ICS844004 is packaged in a small 24-pin
TSSOP package.
• 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
FREQUENCY SELECT FUNCTION TABLE
PIN ASSIGNMENT
Inputs
Output
Frequency
(MHz)
nQ1
Q1
1
24
23
22
21
20
19
18
17
16
15
14
13
nQ2
Input
M Divider N Divider M/N Divider
Value
2
Q2
Frequency F_SEL1 F_SEL0
(MHz)
3
4
VDDo
Q0
VDDO
Q3
Value
Value
26.5625
26.5625
26.5625
26.5625
26.04166
23.4375
0
0
1
1
0
0
0
1
0
1
1
0
24
24
24
24
24
24
3
4
8
6
4
2
6
8
212.5
159.375
106.25
53.125
156.25
187.5
5
6
7
8
nQ0
MR
nPLL_SEL
nc
nQ3
GND
nc
6
nXTAL_SEL
9
VDDA
TEST_CLK
GND
XTAL_IN
XTAL_OUT
12
4
10
11
12
F_SEL0
VDD
F_SEL1
3
ICS844004
24-Lead TSSOP
4.40mm x 7.8mm x 0.92mm
package body
BLOCK DIAGRAM
Pulldown
2
F_SEL[1:0]
G Package
Top View
Pulldown
nPLL_SEL
Q0
F_SEL[1:0]
0 0 ÷3
nQ0
Pulldown
TEST_CLK
1
0
1
0
0 1 ÷4
Q1
26.5625MHz
XTAL_IN
1 0 ÷6
VCO
637.5MHz
(w/26.5625MHz
Reference)
1 1 ÷12
nQ1
Phase
Detector
OSC
XTAL_OUT
Q2
Pulldown
nXTAL_SEL
nQ2
M = 24 (fixed)
Q3
nQ3
Pulldown
MR
The Preliminary Information presented herein represents a product in prototyping or pre-production. The noted characteristics are based on initial product
characterization.Integrated DeviceTechnology, Incorporated (IDT) reserves the right to change any circuitry or specifications without notice.
IDT™ / ICS™ LVDS FREQUENCY SYNTHESIZER
1
ICS844004AG REV AAUGUST 8, 2006