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ICS7151
Spread Spectrum Clock Generator
Description
The ICS7151-10, -20, -40, and -50 are clock
generators for EMI (Electro Magnetic Interference)
reduction (see below for frequency ranges and
multiplier ratios). Spectral peaks can be attenuated by
slightly modulating the oscillation frequency. Both down
and center spread profiles are selectable. Down spread
maintains an average frequency less than an unspread
clock, and will not exceed the maximum frequency of
an unspread clock.
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, 16.5 to
33.4 MHz, 33.3 to 66.7 MHz, 66.6 to 133.4 MHz
• Provides a spread spectrum clock output (±0.5%,
±1.5% center spread; -1.0%, -3.0% down spread)
• Multiplication rates of x1/2, x1, x2, and x4
• Advanced, low-power CMOS process
Block Diagram
VDD
S1:0 2
ENS
XIN
XOUT
PLL Clock
DataSheet4USy.cnothmesis
and Spread
Spectrum
Circuitry
Clock Buffer/
Crystal
Ocsillator
CKOUT
DataShee
External caps required with crystal for
accurate tuning of the clock
GND
Product Lineup
Product
ICS7151M-10, ICS7151MI-10
ICS7151M-20, ICS7151MI-20
ICS7151M-40, ICS7151MI-40
ICS7151M-50, ICS7151MI-50
Input Frequency Range
16.5 MHz to 33.4 MHz
16.5 MHz to 33.4 MHz
16.5 MHz to 33.4 MHz
16.5 MHz to 33.4 MHz
Multiplier Ratio
X1
X2
X4
X1/2
Output Frequency Range
16.5 MHz to 33.4 MHz
33.3 MHz to 66.7 MHz
66.6 MHz to 133.4 MHz
8.3 MHz to 16.7 MHz
MDS 7151 E
1
Revision 012306
DataSheet4U.com
Integrated Circuit Systems, Inc. ● 525 Race Street, San Jose, CA 95126 ● tel (408) 297-1201 ● www.icst.com
DataSheet4 U .com
www.DataSheet4U.com
ICS7151
Spread Spectrum Clock Generator
Pin Assignment
XIN
GND
S0
S1
18
27
36
45
8 pin (150 mil) SOIC
XOUT
VDD
ENS
CKOUT
Spread Direction and Percentage
Select Table
S1
Pin 4
(note1)
S0
Pin 3
(note1)
00
01
10
11
ENS
(note 2)
0
1
Spread
Direction
Spread
Percentage (%)
Center
±1.5
Center
±0.5
Down
-1.0
Down
-3.0
Spread Spectrum
OFF
ON
et4U.com
Pin Descriptions
Notes:
1. The modulation rate varies with input frequency.
2. Spread will default to ON when ENS pin is left open.
Pin
Number
1
2
3
4
5
6
7
8
Pin
Name
XIN
GND
S0
S1
CKOUT
ENS
VDD
XOUT
Pin Type
DataSheet4U.com Pin Description
Input Resonator connection pin/clock input pin.
Power Connect to ground.
Input Select pin 0. Modulation rate setting pin.
Input Select pin 1. Modulation rate setting pin.
Output Modulated clock output pin.
Input Modulation enable setting pin. Internal pull-up resistor.
Power Connect to +3.3 V.
Output Resonator connection pin.
DataShee
MDS 7151 E
2
Revision 012306
DataSheet4U.com
Integrated
Circuit
Systems,
Inc.
●
525
Race
Street,
San
Jose,
CA
95126
●
tel
(408)
297-1201
●
www.icst.com
DataSheet4 U .com
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