W42C31
Model | W42C31 |
Description | Spread Spectrum Frequency Timing Generator |
PDF file | Total 6 pages (File size: 140K) |
Chip Manufacturer | CYPRESS |
W42C31-04
Spread Spectrum Frequency Timing Generator
Features
• Maximized EMI suppression using Cypress’s Spread
Spectrum technology
• Generates a spread spectrum 2.3X copy of the input
• Integrated loop filter components
• Operates with a 5V supply
• Low power CMOS design
• Available in 8-pin SOIC (Small Outline Integrated
Circuit)
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
W42C31-04
FS0
0
1
Oscillator
Input
Frequency
(MHz)
20 to 30
20 to 30
XTAL Input
Frequency
(MHz)
20 to 30
20 to 30
Output
Frequency
(MHz)
2.3f
IN
±0.625%
2.3f
IN
±1.875%
Overview
The W42C31-04 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
Simplified Block Diagram
5.0V
Pin Configuration
SOIC
X1
XTAL
Input
W42C31-04
X2
W42C31-04
Spread Spectrum
Output
(EMI suppressed)
X1
X2
GND
FS0
1
2
3
4
8
7
6
5
REFOUT
SSON#
VDD
CLKOUT
5.0V
Oscillator or Reference
Input
W42C31-04
Spread Spectrum
Output
(EMI suppressed)
Cypress Semiconductor Corporation
•
3901 North First Street
•
San Jose
•
CA 95134 •
408-943-2600
September 29, 1999, rev. **