W42C31-09 Datasheet, PDF (1/7 Pages) Cypress Semiconductor – Spread Spectrum Frequency Timing Generator

W42C31-09
Spread Spectrum Frequency Timing Generator
Features
• Maximized EMI suppression using Cypress’s Spread
Spectrum technology
• Generates a spread spectrum copy of the provided
input
• Integrated loop filter components
• Operates with a 3.3V or 5V supply
• Low-power CMOS design
• Available in 8-pin SOIC (Small Outline Integrated
Circuit)
Overview
The W42C31-09 incorporates the latest advances in PLL
spread spectrum frequency synthesizer techniques. By fre-
quency modulating the output with a low-frequency carrier,
EMI is greatly reduced. Use of this technology allows systems
to pass increasingly difficult EMI testing without resorting to
costly shielding or redesign.
In a system, not only is EMI reduced in the various clock lines,
but also in all signals which are synchronized to the clock.
Therefore, the benefits of using this technology increase with
the number of address and data lines in the system. The Sim-
plified Block Diagram shows a simple implementation.
Table 1. Frequency Spread Selection
W42C31-09
FS1 FS0
0
0
0
1
1
0
1
1
Input Frequency
(MHz)
30 to 55
30 to 55
30 to 55
30 to 55
Output Frequency
(MHz)
f_IN ±0.625%
f_IN ±1.25%
f_IN ±2.5%
f_IN –3.75%
Simplified Block Diagram
Pin Configuration
VDD
Oscillator or Reference
Input
W42C31-09
Spread Spectrum
Output
(EMI suppressed)
CLKIN
NC
GND
FS1
SOIC
1
8 SSON#
2
7 CLKOUT
3
6 FS0
4
5 VDD
Cypress Semiconductor Corporation • 3901 North First Street • San Jose • CA 95134 • 408-943-2600
January 25, 2000, rev. *B