PRELIMINARY
ICS8421004I
FEMTOCLOCKS™ CRYSTAL-TO-
HSTL FREQUENCY SYNTHESIZER
Integrated
Circuit
Systems, Inc.
GENERAL DESCRIPTION
FEATURES
The ICS8421004I is a 4 output HSTL Synthesizer • Four HSTL outputs (VOHmax = 1.4)
ICS
optimized to generate Fibre Channel reference
• Selectable crystal oscillator interface
HiPerClockS™
clock frequencies and is a member of the
or LVCMOS/LVTTL single-ended input
HiPerClocksTM family of high performance clock
solutions from ICS. Using a 26.5625MHz 18pF
• Supports the following output frequencies: 212.5MHz,
parallel resonant crystal, the following frequencies can be
generated based on the two frequency select pins (F_SEL[1:0]):
212.5MHz, 187.5MHz, 159.375MHz, 156.25, 106.25MHz and
53.125MHz. The ICS8421004I uses ICS’ 3rd generation low
phase noise VCO technology and can achieve 1ps or lower
typical rms phase jitter, easily meeting Fibre Channel jitter
requirements.The ICS8421004I is packaged in a small 24-pin
TSSOP package.
187.5MHz, 159.375MHz, 156.25MHz, 106.25MHz, 53.125MHz
• VCO range: 560MHz - 680MHz
• RMS phase jitter @ 212.5MHz, using a 26.5625MHz crystal
(637kHz - 10MHz): 0.59ps (typical)
• Power supply modes:
Core/Output
3.3V/1.8V
2.5V/1.8V
• -40°C to 85°C ambient operating temperature
FREQUENCY SELECT FUNCTION TABLE
PIN ASSIGNMENT
1
24
23
22
21
20
19
18
nQ2
Q2
nQ1
Q1
Inputs
Input
Frequency
(MHz)
Output
Frequency
(MHz)
2
M Divider N Divider
M/N
Divider Value
3
4
VDDO
Q0
VDDO
Q3
F_SEL1 F_SEL0
Value
24
Value
3
5
26.5625
26.5625
26.5625
26.5625
26.04166
23.4375
0
0
1
1
0
0
0
1
0
1
1
0
8
6
4
2
6
8
212.5
159.375
106.25
53.125
156.25
187.5
nQ0
nQ3
6
MR
GND
24
24
24
24
24
4
6
7
8
9
10
11
12
nPLL_SEL
nc
nc
17
16
15
14
13
nXTAL_SEL
VDDA
TEST_CLK
GND
XTAL_IN
12
4
F_SEL0
VDD
F_SEL1
XTAL_OUT
3
ICS8421004I
24-LeadTSSOP
4.40mm x 7.8mm x 0.92mm
BLOCK DIAGRAM
F_SEL[1:0]
Pulldown
2
package body
G Package
TopView
Pulldown
nPLL_SEL
Q0
F_SEL[1:0]
nQ0
Pulldown
TEST_CLK
0 0 ÷3
0 1 ÷4
1 0 ÷6
1 1 ÷12
1
0
1
0
Q1
26.5625MHz
XTAL_IN
nQ1
Phase
Detector
VCO
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 Circuit Systems, Incorporated (ICS) reserves the right to change any circuitry or specifications without notice.
8421004AGI
www.icst.com/products/hiperclocks.html
REV. A MARCH 29, 2005
1