ICS181-51
Low EMI Clock Generator
Description
Features
The ICS181-51 generates a low EMI output clock from
a clock or crystal input. The device uses ICS’
proprietary mix of analog and digital Phase-Locked
Loop (PLL) technology to spread the frequency
spectrum of the output, thereby reducing the frequency
amplitude peaks by several dB.
• Pin and function compatible to Cypress W181-51
• Packaged in 8-pin SOIC
• Provides a spread spectrum output clock
• Accepts a clock input and provides same frequency
dithered output
• Input frequency of 28 to 75 MHz for Clock input
The ICS181-51 offers center spread selection of
+/-0.625% and +/-1.875%. Refer to the MK1714-01/02
for the widest selection of input frequencies and
multipliers.
• Peak reduction by 7dB - 14dB typical on 3rd - 19th
odd harmonics
• Spread percentage selection for +/-0.625% and
+/-1.875%
ICS offers a complete line of EMI reducing clock
generators. Consult us when you need to remove
crystals and oscillators from your board.
• Operating voltage of 3.3 V and 5 V
• Advanced, low-power CMOS process
Block Diagram
VDD
FS2:1
SS%
PLLClock
Synthesis
andSpread
Spectrum
Circuitry
CLK
X1/CLKIN
ClockBuffer/
Crystal
Oscillator
X2
GND
MDS 181-51 A
1
Revision 110404
Integrated Circuit Systemsl525 Race Street, San Jose, CA 95126 l tel (408) 297-1201 l www.icst.com