ICS8431-01
200MHZ, LOW JITTER,
LVPECLFREQUENCY SYNTHESIZER
Integrated
Circuit
Systems, Incꢀ
GENERAL DESCRIPTION
FEATURES
The ICS8431-01 is a general purpose clock • Fully integrated PLL
,&6
frequency synthesizer for IA64/32 application and
• Differential 3.3V LVPECLoutput
HiPerClockS™
a member of the HiPerClockS™ family of High
Performance Clock Solutions from ICS. The
ICS8431-01 consists of one independent low
• 200MHz output frequency
• 48% to 52% duty cycle
• Crystal oscillator interface
bandwidth PLL timing channel. A 16.666MHz crystal is used
as the input to the on-chip oscillator. The M is configured to
produce a fixed output frequency of 200MHz.
• Spread Spectrum Clocking (SSC) fixed at 1/2% modulation
for environments requiring ultra low EMI. Typical10dB EMI
reduction can be achieved with spread spectrum modulation
Programmable features of the ICS8431-01 support four
operational modes. The four modes are spread spectrum
clocking (SSC), non-spread spectrum clock and two test
modes which are controlled by the SSC_CTL[1:0] pins. Un-
like other synthesizers, the ICS8431-01 can immediately
change spread-spectrum operation without having to reset
the device.
• LVTTL/ LVCMOS control inputs
• PLL bypass modes supporting in-circuit testing and on-chip
functional block characterization
• 28 lead SOIC
In SSC mode, the output clock is modulated in order to
achieve a reduction in EMI. In one of the PLL bypass test
modes, the PLL is disconnected as the source to the
differential output allowing an external source to be
connnected to the TEST_I/O pin. This is useful for in-
circuit testing and allows the differential output to be driven
at a lower frequency throughout the system clock tree. In the
other PLL bypass mode, the oscillator divider is used as the
source to both the M and the Fout divide by 2. This is useful
for characterizing the oscillator and internal dividers.
• RMS cycle-to-cycle jitter of 2ps
• Typical cycle-to-cycle jitter of 18ps
• 0° to 85°C ambiant operating temperature
BLOCK DIAGRAM
PIN ASSIGNMENT
nc
nc
nc
nc
1
2
3
4
28
27
26
25
24
23
22
21
20
19
18
17
16
15
nc
XTAL1
OSC
VDDI
XTAL2
XTAL1
nc
nc
VDDA
VEE
XTAL2
÷ 16
nc
nc
nc
nc
nc
5
6
7
8
PLL
9
RESERVED
nc
PHASE
DETECTOR
SSC_CTL0
SSC_CTL1
VEE
TEST_I/O
VDD
10
11
12
13
14
VDDO
FOUT
nFOUT
VEE
VCO
÷ 2
FOUT
nFOUT
÷ M
ICS8431-01
28-Lead SOIC
M Package
TEST_I/O
SSC_CTL0
SSC
Top View
Control
SSC_CTL1
Logic
ICS8431CM-01
www.icst.com/products/hiperclocks.html
REV. A JUNE 5, 2001
1