Integrated
Circuit
Systems, Inc.
ICS9112-16
Low Skew Output Buffer
General Description
The
ICS9112-16
is a high performance, low skew, low jitter
clock driver. It uses a phase lock loop (PLL) technology
to align, in both phase and frequency, the REF input with
the CLKOUT signal. It is designed to distribute high speed
clocks in PC systems operating at speeds from 25 to
133 MHz.
ICS9112-16
is a zero delay buffer that provides
synchronization between the input and output. The
synchronization is established via CLKOUT feed back to
the input of the PLL. Since the skew between the input and
output is less than +/- 350 pS, the part acts as a zero delay
buffer.
The
ICS9112-16
comes in an eight pin 150 mil SOIC or 173
mil TSSOP package. It has five output clocks. In the
absence of REF input, will be in the power down mode. In
this mode, the PLL is turned off and the output buffers are
pulled low. Power down mode provides the lowest power
consumption for a standby condition.
Features
•
•
•
•
•
•
•
•
Zero input - output delay
Frequency range 25 - 133 MHz (3.3V)
High loop filter bandwidth ideal for Spread
Spectrum applications.
Less than 200 ps Jitter between outputs
Skew controlled outputs
Skew less than 250 ps between outputs
Available in 8 pin 150 mil SOIC
or 173 mil TSSOP package.
3.3V ±10% operation
Block Diagram
Pin Configuration
8 pin SOIC, TSSOP
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ICS9112-16
Pin Descriptions
PIN NUMBER
1
2
3
4
5
6
7
8
PIN NAME
REF
2
CLK2
3
CLK1
3
GND
CLK3
3
VDD
CLK4
3
CLKOUT
3
TYPE
IN
OUT
OUT
PWR
OUT
PWR
OUT
OUT
Input reference frequency.
Buffered clock output
Buffered clock output
Ground
Buffered clock output
Power Supply (3.3V)
Buffered clock output
Buffered clock output. Internal feedback on this pin
DESCRIPTION
Notes:
1. Guaranteed by design and characterization. Not subject to 100% test.
2. Weak pull-down
3. Weak pull-down on all outputs
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2
ICS9112-16
Absolute Maximum Ratings
Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . 7.0 V
Logic Inputs . . . . . . . . . . . . . . . . . . . . . . . . . GND –0.5 V to V
DD
+0.5 V
Ambient Operating Temperature . . . . . . . . . . 0°C to +70°C
Storage Temperature . . . . . . . . . . . . . . . . . . . –65°C to +150°C
Stresses above those listed under
Absolute Maximum Ratings
may cause permanent damage to the device. These
ratings are stress specifications only and functional operation of the device at these or any other conditions above those
listed in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions
for extended periods may affect product reliability.
Electrical Characteristics at 3.3V
V
DD
= 3.0 – 3.6 V, T
A
= 0 – 70
°
C unless otherwise stated
DC Characteristics
PARAMETER
Input Low Voltage
Input High Voltage
Input Low Current
Input High Current
Output Low Voltage
1
Output High Voltage
1
Power Down Supply
Current
Supply Current
SYMBOL
V
IL
V
IH
I
IL
I
IH
V
OL
V
OH
I
DD
I
DD
V
IN
=0V
V
IN
=V
DD
I
OL
= 25mA
I
OH
= 25mA
REF = 0 MHz
Unloaded oututs at 66.66 MHz
SEL inputs at V
DD
or GND
2.4
2.0
19
0.10
0.25
2.9
0.3
30.0
50.0
40.0
50.0
100.0
0.4
TEST CONDITIONS
MIN
TYP
MAX
0.8
UNITS
V
V
µA
µA
V
V
µA
mA
Notes:
1. Guaranteed by design and characterization. Not subject to 100% test.
2. All Skew specifications are mesured with a 50Ω transmission line, load teminated with 50Ω to 1.4V.
3. Duty cycle measured at 1.4V.
4. Skew measured at 1.4V on rising edges. Loading must be equal on outputs.
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ICS9112-16
Switching Characteristics
PARAMETER
Output period
Input period
Duty Cycle
1
Duty Cycle
1
Rise Time
1
Fall Time
1
Delay, REF Rising
Edge to CLKOUT
Rising Edge
1, 2
Output to Output
Skew
1
Device to Device
Skew
1
Cycle to Cycle
Jitter
1
PLL Lock Time
1
Jitter ; Absolute
Jitter
1
Jitter ; 1 - Sigma
1
SYMBOL
t1
t1
Dt1
Dt2
tr1
tf1
Dr1
Tskew
Tdsk-Tdsk
Tcyc-Tcyc
tLOCK
Tjabs
Tj1s
CONDITION
With CL=30pF
With CL=30pF
Measured at 1.4V; CL=30pF
Measured at VDD/2 Fout
<66.6MHz
Measured between 0.8V and 2.0V:
CL=30pF
Measured between 2.0V and 0.8V;
CL=30pF
Measured at 1.4V
All outputs equally loaded,
CL=20pF
Measured at VDD/2 on the
CLKOUT pins of devices
Measured at 66.66 MHz, loaded
outputs
Stable power supply, valid clock
presented on REF pin
@ 10,000 cycles
CL=30pF
@ 10,000 cycles
CL=30pF
-100
70
14
0
MIN
40.00
(25)
40.00
(25)
40.0
45
50
50
1.2
1.2
0
TYP
MAX
7.5
(133)
7.5
(133)
60
55
1.5
1.5
±350
250
700
200
1.0
100
30
UNITS
ns
(MHz)
ns
(MHz)
%
%
ns
ns
ps
ps
ps
ps
ms
ps
ps
Notes:
1. Guaranteed by design and characterization. Not subject to 100% test.
2. REF input has a threshold voltage of 1.4V
3. All parameters expected with loaded outputs
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ICS9112-16
Output to Output Skew
The skew between CLKOUT and the CLK(1-4) outputs is not dynamically adjusted by the PLL. Since CLKOUT is one
of the inputs to the PLL, zero phase difference is maintained from REF to CLKOUT. If all outputs are equally loaded,
zero phase difference will maintained from REF to all outputs.
If applications requiring zero output-output skew, all the outputs must equally loaded.
If the CLK(1-4) outputs are less loaded than CLKOUT, CLK(1-4) outputs will lead it; and if the CLK(1-4) is more loaded
than CLKOUT, CLK(1-4) will lag the CLKOUT.
Since the CLKOUT and the CLK(1-4) outputs are identical, they all start at the same time, but different loads cause
them to have different rise times and different times crossing the measurement thresholds.
REF input and
all outputs
loaded Equally
REF input and CLK(1-4)
outputs loaded equally, with
CLKOUT loaded More.
REF input and CLK(1_4)
outputs loaded equally, with
CLKOUT loaded Less.
Timing diagrams with different loading configurations
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