W42C32-05 Datasheet, PDF (1/8 Pages) Cypress Semiconductor – Spread Spectrum Frequency Timing Generator

W42C32-05
Spread Spectrum Frequency Timing Generator
Features
• Maximized EMI suppression using Cypress’s Spread
Spectrum technology
• Generates a spread spectrum timing signal
• Reduces measured EMI by as much as 12 dB
• Integrated loop filter components
• Requires a single low-cost fundamental crystal (or
other frequency reference) for proper operation
• Special spread spectrum control functions
• Low-power CMOS design
• Available in 16-pin SOIC package, (300 mil)
Overview
The W42C32 modulates the output of a single PLL in order to
‘spread’ the bandwidth of a synthesized clock and, more im-
portantly, decrease the peak amplitudes of its fundamental
harmonics. Since peak amplitudes are reduced, the radiated
electromagnetic emissions of the W42C32-05 are significantly
lower than the typical narrow band signal produced by oscilla-
tors and most frequency generators. Lowering a signal’s am-
plitude by increasing its bandwidth is a method of reducing
EMI called ‘spread spectrum frequency timing generation’.
This patented technique not only reduces the emissions of the
primary clock, but also impacts every signal synchronized to it.
Key Specifications
Cycle-to-Cycle Jitter .................................................... 250 ps
45/55 Duty Cycle .................................... approximately 1.4V
Selectable Frequency spread
2 ns rise/fall time 0.4V to 2.0V, 3.3V supply
2 ns rise/fall time 0.8V to 2.4V, 5.0V supply
Table 1. Frequency Spread Selection
W42C32-05
REFOUT
FS2 FS1 FS0 (MHz)
CLKOUT
(MHz)
VDD
(V)
0
0
0 22.1148
44.2296 ±
5.0
2.5%
0
0
1 22.1148
44.2296
5.0
±1.5%
0
1
0 14.7456
29.4912 ±
5.0
2.5%
0
1
1
18.432 18.432 ± 2.5% 5.0
1
0
0
14.318
66.66 – 2%
3.3
1
0
1
Reserved
3.3
1
1
0
14.318
100 – 2%
3.3
1
1
1
Reserved
3.3
Pin Configuration
PD#
X1
X2
GND
AGND
FS0
TEST
CLKOUT
SOIC
1
16
2
15
3
14
4
13
5
12
6
11
7
10
8
9
REFOUT
FS2
FS1
SSON#
RESET
VDD
AVDD
REFEN#
Cypress Semiconductor Corporation • 3901 North First Street • San Jose • CA 95134 • 408-943-2600
September 28, 1999, rev. **