Low EMI Clock Generator
Description
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ICS4231-03
Low EMI Clock Generator
Features
• • • •
Pin and function compatible to Cypress W42C31-03 Packaged in 8-pin SOIC (Pb free available) Provides a spread spectrum output clock Accepts a clock or crystal input and provides same frequency dithered output
Description
The ICS4231-03 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.
The ICS4231-03 offers four different center and down spread selections.
Refer to the MK1714-01/02 for the widest selection of input frequencies and multipliers.
ICS offers a complete line of EMI reducing clock generators.
Consult us when you need to remove crystals and oscillators from your board.
• Input clock frequency of 10 to 33 MHz • Peak reduction by 8dB - 14dB typical on 3rd - 19th
odd harmonics
• Spread percentage selections of ±1.
875%, ±1.
0%,
and -2.
0%
• Operating voltage of 5V • Advanced, low-power CMOS process
Block Diagram
VDD
FS1:0 OE# PLL Clock Synthesis and Spread Spectrum Circuitry
CLK
X1/CLKIN X2
Clock Buffer/ Crystal Oscillator
GND
MDS 4231-03 A
1
●
Revision 110404 tel (408) 297-1 201 ● w w w.
i c s t .
c o m
In te grated Circuit Systems ● 5 25 Race Stree t, San Jose, CA 951 26
ICS4231-03 LOW EMI CLOCK GENERATOR
Pin Assignment
X1/CLKIN X2 GND FS0 1 2 3 4 8 7 6 5 OE# FS1 VDD CLKOUT
Output Enable Function Table
OE# (Pin 8) 0 1 Output Status Running Tri-state
8 pin (150 mil) SOIC
0 = connect to GND 1 = connect directly to VDD Note: OE# pin has an internal pull-down resistor
Frequency Range and Spread Table
FS1 (Pin 7) FS0 (Pin 4) Clock Input Frequency (MHz) 10-20 10-20 20-33 20-33 Crystal Input Frequency (MHz) 10-20 10-20 20-25 20-25 Spread Amount
0 0 1 1
0 1 0 1
±1.
875% ±1.
0% ±1.
875% -2.
0%
Note: FS1:0 have internal pull-up resistors
Pin Descriptions
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