ICS7151A-50
MDS 7151A-50 A
1
Revision 102005
Integrated Circuit Systems, Inc.
525 Race Street, San Jose, CA 95126
tel (408) 297-1201
www.icst.com
Spread Spectrum Clock Generator
Description
The ICS7151A-50 is a clock generator for EMI
(Electromagnetic Interference) reduction. Spectral
peaks are attenuated by modulating the system clock
frequency. Down or center spread profiles are
selectable. Down spread will not exceed the maximum
frequency of an unspread clock, and center spread
does not change the average operating frequency of
the system
ICS offers many other clocks for computers and
computer peripherals. Consult ICS when you need to
remove crystals and oscillators from your board.
Features
Operating voltage of 3.3 V 0.3 V
Packaged in 8-pin SOIC
Available in Pb (lead) free package
Input frequency range of 16.5 to 33.4 MHz
Output frequency ranges of 8.3 to 16.7 MHz
Provides a spread spectrum clock output (0.5%,
1.5% center spread; -1.0%, -3.0% down spread)
Multiplication rate of x1/2
Advanced, low-power CMOS process
Pin compatible with the Fujitsu MB88151-500
Block Diagram
PLL Clock
Synthesis
and Spread
Spectrum
Circuitry
S1:0
ENS
CKOUT
2
GND
VDD
Clock Buffer/
Crystal
Ocsillator
XIN
XOUT
External caps required with crystal for
accurate tuning of the clock
Spread Spectrum Clock Generator
MDS 7151A-50 A
2
Revision 102005
Integrated Circuit Systems, Inc.
525 Race Street, San Jose, CA 95126
tel (408) 297-1201
www.icst.com
ICS7151A-50
Pin Assignment
Spread Direction and Percentage
Select Table
Notes:
1. Pin 1 has a pull-up resistor.
Pin Descriptions
XOUT
GND
S0
VDD
S1
CKOUT
ENS
XIN
1
2
3
4
8
7
6
5
8 pin (150 mil) SOIC
S1
Pin 4
S0
Pin 3
Spread
Direction
Spread
Percentage (%)
0
0
Center
1.5
0
1
Center
0.5
1
0
Down
-1.0
1
1
Down
-3.0
ENS
(note 1)
Modulation
0
No Modulation
1
Modulation
Pin
Number
Pin
Name
Pin Type
Pin Description
1
XIN
Input
Crystal pin/clock input pin.
2
GND
Power
Connect to ground.
3
S0
Input
Select pin 0. Spread modulation select.
4
S1
Input
Select pin 1. Spread modulation select.
5
CKOUT
Output
Clock output.
6
ENS
Input
Modulation enable. Internal pull-up resistor.
7
VDD
Power
Connect to +3.3 V.
8
XOUT
Output
Crystal connection pin.
Spread Spectrum Clock Generator
MDS 7151A-50 A
3
Revision 102005
Integrated Circuit Systems, Inc.
525 Race Street, San Jose, CA 95126
tel (408) 297-1201
www.icst.com
ICS7151A-50
External Components
The ICS7151A-50 requires a minimum number of
external components for proper operation.
Decoupling Capacitor
A decoupling capacitor of 0.01F must be connected
between GND and VDD on pins 2 and 7, as close to
these pins as possible. For optimum device
performance, the decoupling capacitor should be
mounted on the component side of the PCB. Avoid the
use of vias in the decoupling circuit.
Series Termination Resistor
Series termination should be used on the clock output.
To series terminate a 50
trace (a commonly used
trace impedance) place a 27
resistor in series with
the clock line, as close to the clock output pin as
possible. The nominal impedance of the clock output is
25
.
PCB Layout Recommendations
For optimum device performance and lowest output
phase noise, the following guidelines should be
observed.
1) The 0.01F decoupling capacitor should be mounted
on the component side of the board as close to the
VDD pin as possible. No vias should be used between
the decoupling capacitor and VDD pin. The PCB trace
to VDD pin should be kept as short as possible, as
should the PCB trace to the ground via.
2) To minimize EMI, the 27
series termination resistor
(if needed) should be placed close to the clock output.
3) An optimum layout is one with all components on the
same side of the board, minimizing vias through other
signal layers. Other signal traces should be routed
away from the ICS7151A-50. This includes signal
traces just underneath the device, or on layers adjacent
to the ground plane layer used by the device.
Crystal Information
The crystal used should be a fundamental mode (do
not use third overtone), parallel resonant. Crystal
capacitors should be connected from pins X1 to ground
and X2 to ground to optimize the initial accuracy. The
value of these capacitors is given by the following
equation:
Crystal caps (pF) = (C
L
- 6) x 2
In the equation, C
L
is the crystal load capacitance. So,
for a crystal with a 16 pF load capacitance, two 20 pF
[(16-6) x 2] capacitors should be used.
Spread Spectrum Profile
The ICS7151A-50 low EMI clock generator uses a
triangular frequency modulation profile for optimal
down stream tracking of zero delay buffers and other
PLL devices. The frequency modulation amplitude is
constant with variations of the input frequency.
Time
F
r
eq
ue
nc
y
Modulation Rate
Spread Spectrum Clock Generator
MDS 7151A-50 A
4
Revision 102005
Integrated Circuit Systems, Inc.
525 Race Street, San Jose, CA 95126
tel (408) 297-1201
www.icst.com
ICS7151A-50
Absolute Maximum Ratings
Stresses above the ratings listed below can cause permanent damage to the ICS7151A-50. These ratings,
which are standard values for ICS commercially rated parts, are stress ratings only. Functional operation of
the device at these or any other conditions above those indicated in the operational sections of the
specifications is not implied. Exposure to absolute maximum rating conditions for extended periods can
affect product reliability. Electrical parameters are guaranteed only over the recommended operating
temperature range.
Overshoot/Undershoot
Recommended Operation Conditions
Item
Rating
Supply Voltage, VDD
-0.5 to 4.0 V
All Inputs and Outputs (referenced to GND)
-0.5 V to VDD+0.5 V
Ambient Operating Temperature
-40 to +85
C
Storage Temperature
-55 to +125
C
Junction Temperature
-40 to +125
C
Soldering Temperature
260
C
Overshoot (V
IOVER
)
VDD + 1.0 V (t
OVER
< 50 ns)
Undershoot (V
IUNDER
)
GND - 1.0 V (t
UNDER
< 50 ns)
Parameter
Min.
Typ.
Max.
Units
Ambient Operating Temperature
-40
+85
C
Power Supply Voltage (measured in respect to GND)
+3.0
3.3
3.6
V
Input pin
V
IOVER
< V
DD
+ 1.0 V
V
IUNDER
< GND - 1.0 V
t
OVER
< 50 ns
t
UNDER
< 50 ns
V
DD
GND
Spread Spectrum Clock Generator
MDS 7151A-50 A
5
Revision 102005
Integrated Circuit Systems, Inc.
525 Race Street, San Jose, CA 95126
tel (408) 297-1201
www.icst.com
ICS7151A-50
DC Electrical Characteristics
Unless stated otherwise, VDD = 3.3 V 0.3 V, Ambient Temperature -40 to +85
C
AC Electrical Characteristics
Unless stated otherwise, VDD = 3.3 V 0.3 V, Ambient Temperature -40 to +85
C
Parameter
Symbol
Conditions
Min.
Typ.
Max.
Units
Operating Voltage
VDD
3.0
3.3
3.6
V
Supply Current
IDD
No load, at 3.3 V,
output = 24 MHz
10
14
mA
Input Frequency
16.5
33.4
MHz
Input High Voltage
V
IH
XIN, S0, S1, ENS
VDD * 0.8
VDD + 0.3
V
Input Low Voltage
V
IL
XIN, S0, S1, ENS
0.0
VDD * 0.20
V
Output High Voltage
V
OH
CKOUT, I
OH
= -4 mA
2.0
V
Output Low Voltage
V
OL
CKOUT, I
OL
= 4 mA
0.4
V
Input Capacitance
C
IN
XIN, S0, S1, ENS
16
pF
Load Capacitance
C
L
CKOUT, 8.3 to 66.7
MHz
15
pF
CKOUT, 66.7 to 100
MHz
10
pF
CKOUT, 100 to 133.4
MHz
7
pF
Input Pull-up Resistor
R
PU
ENS
100
240
400
k
Parameter
Symbol
Conditions
Min.
Typ.
Max.
Units
Oscillation Frequency
f
X
Fundamental
oscillation
16.5
33.4
MHz
Input Frequency
f
IN
XIN
16.5
33.4
MHz
Output Frequency
f
OUT
CKOUT, 2-frequency
division
8.3
16.7
MHz
Input Clock Duty Cycle
XIN, 16.5 to 33.4 MHz
40
50
60
%
Output Clock Duty Cycle
t
DCC
CKOUT, 1.5 V
40
60
%
Output Slew Rate
CKOUT, 0.4 to 2.4 V,
load capacitance 15 pF
0.5
TBD
3.0
V/ns
Cycle to Cycle Jitter
t
JC
No load, standard
deviation
TBD
200
ps
Lock Time
t
LK
CKOUT
2
5
ms
Modulation Frequency
f
MOD
CKOUT=TBD
33
kHz
Spread Spectrum Clock Generator
MDS 7151A-50 A
6
Revision 102005
Integrated Circuit Systems, Inc.
525 Race Street, San Jose, CA 95126
tel (408) 297-1201
www.icst.com
ICS7151A-50
Input Frequency (f
IN
= 1/t
IN
)
Output Slew Rate
Thermal Characteristics
Parameter
Symbol
Conditions
Min.
Typ.
Max.
Units
Thermal Resistance Junction to
Ambient
JA
Still air
150
C/W
JA
1 m/s air flow
140
C/W
JA
3 m/s air flow
120
C/W
Thermal Resistance Junction to Case
JC
40
C/W
CKIN
t
IN
0.8 V
DD
CKOUT
SR = (2.4 - 0.4) /t
r
, SR = (2.4 - 0.4) /t
f
t
r
2.4 V
t
f
0.4 V
Spread Spectrum Clock Generator
MDS 7151A-50 A
7
Revision 102005
Integrated Circuit Systems, Inc.
525 Race Street, San Jose, CA 95126
tel (408) 297-1201
www.icst.com
ICS7151A-50
Package Outline and Package Dimensions
(8-pin SOIC, 150 Mil. Body)
Package dimensions are kept current with JEDEC Publication No. 95
Ordering Information
Parts that are ordered with a "LF" suffix to the part number are the Pb-Free configuration and are RoHS compliant.
While the information presented herein has been checked for both accuracy and reliability, Integrated Circuit Systems (ICS)
assumes no responsibility for either its use or for the infringement of any patents or other rights of third parties, which would
result from its use. No other circuits, patents, or licenses are implied. This product is intended for use in normal commercial
applications. Any other applications such as those requiring extended temperature range, high reliability, or other extraordinary
environmental requirements are not recommended without additional processing by ICS. ICS reserves the right to change any
circuitry or specifications without notice. ICS does not authorize or warrant any ICS product for use in life support devices or
critical medical instruments.
Part / Order Number
Marking
Shipping Packaging
Package
Temperature
ICS7151AM-50
7151AM50
Tubes
8-pin SOIC
0 to +70
C
ICS7151AM-50T
7151AM50
Tape and Reel
8-pin SOIC
0 to +70
C
ICS7151AM-50LF
151AM50L
Tubes
8-pin SOIC
0 to +70
C
ICS7151AM-50LFT
151AM50L
Tape and Reel
8-pin SOIC
0 to +70
C
ICS7151AMI-50
151AMI50
Tubes
8-pin SOIC
-40 to +85
C
ICS7151AMI-50T
151AMI50
Tape and Reel
8-pin SOIC
-40 to +85
C
ICS7151AMI-50LF
51AMI50L
Tubes
8-pin SOIC
-40 to +85
C
ICS7151AMI-50LFT
51AMI50L
Tape and Reel
8-pin SOIC
-40 to +85
C
INDEX
AREA
1 2
8
D
E
SEATING
PLANE
A1
A
e
- C -
B
.10 (.004)
C
C
L
H
h x 45
*For reference only. Controlling dimensions in mm.
Millimeters
Inches*
Symbol
Min
Max
Min
Max
A
1.35
1.75
.0532
.0688
A1
0.10
0.25
.0040
.0098
B
0.33
0.51
.013
.020
C
0.19
0.25
.0075
.0098
D
4.80
5.00
.1890
.1968
E
3.80
4.00
.1497
.1574
e
1.27 BASIC
0.050 BASIC
H
5.80
6.20
.2284
.2440
h
0.25
0.50
.010
.020
L
0.40
1.27
.016
.050
0
8
0
8
Spread Spectrum Clock Generator
MDS 7151A-50 A
8
Revision 102005
Integrated Circuit Systems, Inc.
525 Race Street, San Jose, CA 95126
tel (408) 297-1201
www.icst.com
ICS7151A-50
Revision History
Rev.
Originator
Date
Description of Change
A
J. Sarma
10/20/05
Rev A; new device/datasheet.
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