PRELIMINARY
ICS8421004I-01
FEMTOCLOCKS™ CRYSTAL-TO-
HSTL FREQUENCY SYNTHESIZER
Integrated
Circuit
Systems, Inc.
GENERAL DESCRIPTION
FEATURES
The ICS8421004I-01 is a 4 output HSTL • Four HSTL outputs (VOHmax = 1.4V)
ICS
Synthesizer optimized to generate Ethernet
• Selectable crystal oscillator interface or
reference clock frequencies and is a member of
LVCMOS/LVTTL single-ended input
HiPerClockS™
the HiPerClocksTM family of high performance
clock solutions from ICS. Using a 25MHz 18pF
• Supports the following output frequencies: 156.25MHz,
125MHz, 62.5MHz
parallel resonant crystal, the following frequencies can be
generated based on the 2 frequency select pins (F_SEL[1:0]):
156.25MHz, 125MHz and 62.5MHz. The ICS8421004I-01
uses ICS’ 3rd generation low phase noise VCO technology
and can achieve 1ps or lower typical rms phase jitter, easily
meeting Ethernet jitter requirements.The ICS8421004I-01 is
packaged in a small 24-pin TSSOP package.
• VCO range: 560MHz - 680MHz
• RMS phase jitter @ 156.25MHz, using a 25MHz crystal
(1.875MHz - 20MHz): 0.44ps (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
nQ1
Q1
1
24
23
22
nQ2
Q2
Output
Frequency
(25MHz Ref.)
2
M Divider N Divider
M/N
Divider Value
3
4
5
6
7
8
9
10
11
12
VDDO
Q0
VDDO
Q3
F_SEL1 F_SEL0
Value
Value
21
20
19
18
17
16
15
14
13
0
0
1
1
0
1
0
1
25
4
6.25
156.25
125
nQ0
MR
nPLL_SEL
nc
nQ3
GND
VDD
nXTAL_SEL
TEST_CLK
GND
25
25
25
5
5
10
2.5
62.5
VDDA
not used
not used
F_SEL0
VDD
XTAL_IN
F_SEL1
XTAL_OUT
ICS8421004I-01
24-LeadTSSOP
4.40mm x 7.8mm x 0.92mm
BLOCK DIAGRAM
F_SEL[1:0]
Pulldown
2
package body
Pulldown
nPLL_SEL
G Package
TopView
Q0
F_SEL[1:0]
nQ0
Pulldown
TEST_CLK
0 0 ÷4
1
0
1
0
0 1 ÷5
Q1
25MHz
XTAL_IN
1 0 ÷10
1 1 Not Used
nQ1
Phase
Detector
VCO
OSC
XTAL_OUT
Q2
Pulldown
nXTAL_SEL
nQ2
M = 25 (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-01
www.icst.com/products/hiperclocks.html
REV. A MACH 29, 2005
1