W42C32-05M 查看數據表（PDF） - Cypress Semiconductor
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W42C32-05M Datasheet PDF : 8 Pages
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2-05M
W42C32-05M
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
• Power-down mode reduces current consumption and
disables the clock outputs
• Available in 16-pin SOIC package (300 mil)
Overview
The W42C32-05M modulates the output of a single PLL in
order to ‘spread’ the bandwidth of a synthesized clock and,
more importantly, decrease the peak amplitudes of its funda-
mental harmonics. Since peak amplitudes are reduced, the
radiated electromagnetic emissions of the W42C32-05M are
significantly lower than the typical narrow band signal pro-
duced by oscillators and most frequency generators. Lowering
a signal’s amplitude by increasing its bandwidth is a method of
reducing EMI called ‘spread spectrum frequency timing gen-
eration’. This patented technique not only reduces the emis-
sions of the primary clock, but also impacts every signal syn-
chronized 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
W42C32-05M
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
January 5, 2001, rev. **
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