Peak Reducing EMI Solution
W181
Cypress Semiconductor Corporation
•
3901 North First Street
•
San Jose
•
CA 95134
•
408-943-2600
July 21, 2000, rev. *B
Features
• Cypress PREMIS™ family offering
• Generates an EMI optimized clocking signal at the out-
put
• Selectable input to output frequency
• Single 1.25% or 3.75% down or center spread output
• Integrated loop filter components
• Operates with a 3.3V or 5V supply
• Low power CMOS design
• Available in 8-pin SOIC (Small Outline Integrated Cir-
cuit) or 14-pin TSSOP (Thin Shrink Small Outline Pack-
age select options only)
Key Specifications
Supply Voltages: ........................................... VDD = 3.3V±5%
or VDD = 5V±10%
Frequency Range: ............................ 28 MHz
≤ F
in ≤ 75 MHz
Crystal Reference Range.................. 28 MHz
≤ F
in ≤ 40 MHz
Cycle to Cycle Jitter: ....................................... 300 ps (max.)
Selectable Spread Percentage: ....................1.25% or 3.75%
Output Duty Cycle: ............................... 40/60% (worst case)
Output Rise and Fall Time: .................................. 5 ns (max.)
Table 1. Modulation Width Selection
SS%
W181-01, 02, 03
Output
W181-51, 52, 53
Output
0Fin ≥ Fout ≥ Fin –
1.25%
Fin + 0.625% ≥ Fin≥
– 0.625%
1Fin ≥ Fout ≥ Fin –
3.75%
Fin + 1.875% ≥ Fin≥
–1.875%
Table 2. Frequency Range Selection
W181 Option#
FS2
FS1
-01, 51
(MHz)
-02, 52
(MHz)
-03, 53
(MHz)
0
0
28
≤ F
IN ≤ 38
28
≤ F
IN ≤ 38
N/A
0
1
38
≤ F
IN ≤ 48
38
≤ F
IN ≤ 48
N/A
1
0
46
≤ F
IN ≤ 60
N/A
46
≤ F
IN ≤ 60
1
1
58
≤ F
IN ≤ 75
N/A
58
≤ F
IN ≤ 75
PREMIS is a trademark of Cypress Semiconductor Corporation.
Simplified Block Diagram
Pin Configurations
8
7
6
5
1
2
3
4
CLKIN or X1
NC or X2
GND
SS%
SSON#
FS1
VDD
CLKOUT
8
7
6
5
1
2
3
4
CLKIN or X1
NC or X2
GND
SS%
FS2
FS1
VDD
CLKOUT
SOIC
Spread Spectrum
W181
(EMI suppressed)
3.3 or 5.0V
Oscillator or
Spread Spectrum
W181
(EMI suppressed)
3.3 or 5.0V
XTAL
X1
X2
Reference Input
Input
Output
Output
40 MHz
Max.
8
1
2
3
4
CLKIN or X1
NC or X2
GND
SS%
NC
FS1
VDD
CLKOUT
5
6
7
9
10
11
12
13
14
FS2
NC
NC
NC
NC
NC
TSSOP
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