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Alliance Semiconductor |
November 2003
P2041A
rev F
Versatile EMI Reduction IC
Features
FCC approved method of EMI attenuation
Provides up to 20 dB of EMI suppression
Generates a low EMI spread spectrum clock
of the input frequency
Optimized for 25 MHz to 60MHz input
frequency range
Internal loop filter minimizes external
components and board space
4 selectable spread ranges
SSON control pin for spread spectrum
enable and disable options
Characterizes to work with EMI-Lator®, EMC
simulation program.
Low cycle-to-cycle jitter
3.3 V or 5.0 V operating range
16 mA output drives
TTL or CMOS compatible outputs
Low power CMOS design
Available in 8 pin SOIC and TSSOP
the clock source which provides system wide
reduction of EMI of all clock dependent signals. The
P2041 allows significant system cost savings by
reducing the number of circuit board layers and
shielding that are traditionally required to pass EMI
regulations.
The P2041 uses the most efficient and optimized
modulation profile approved by the FCC and is
implemented in a proprietary all-digital method.
The P2041 modulates the output of a single PLL in
order to “spread” the bandwidth of a synthesized
clock and, more importantly, decreases the peak
amplitudes of its harmonics. This results in
significantly lower system EMI compared to the
typical narrow band signal produced by oscillators
and most frequency generators. Lowering EMI by
increasing a signal’s bandwidth is called “spread
spectrum clock generation”.
Product Description
Thewww.DataSheet4U.com P2041 is a selectable spread spectrum
frequency modulator designed specifically for PC
peripheral and embedded controller markets .The
P2041 reduces electromagnetic interference (EMI) at
Block Diagram
Applications
The P2041 is targeted towards the embedded
controller market and PC peripheral markets
including scanners, MFP’s, printers, PDA, IA , and
GPS devices.
Alliance Semiconductor
2575, Augustine Drive • Santa Clara, CA • Tel: 408.855.4900 • Fax: 408.855.4999 • www.alsc.com
Notice: The information in this document is subject to change without notice.
November 2003
rev F
Pin Configuration
P2041A
Pin Description
Pin#
1
2
3
Pin Name
XIN/CLK
XOUT
SR1
4
www.DataSheet4U.com
5
VSS
SSON
6 ModOUT
7 SR0
8 VDD
Type
I
I
I
P
I
O
I
P
Description
Connect to crystal or externally generated clock signal.
Connect to crystal. No connect if externally generated clock signal is used.
Digital logic input used to select Spreading Range (see Table 1). This pin
has an internal pull-up resistor.
Ground Connection. Connect to system ground.
Digital logic input used to enable Spread Spectrum function (Active Low).
Spread Spectrum function enable when low. This pin has an internal pull-
low resistor.
Spread Spectrum Clock Output.
Digital logic input used to select Spreading Range (see Table 1). This pin
has an internal pull-up resistor.
Connect to +3.3V or +5.0V
Table 1 - Spread Range Selection
FS0 SR0 Spreading Range Input Frequency
00
01
10
11
+/- 1.50%
+/- 2.50%
+/- 0.50%
+/- 1.00%
(Fin/40)*34.72 KHz
(Fin/40)*34.72 KHz
(Fin/40)*34.72 KHz**
(Fin/40)*34.72 KHz**
Modulation rate
0
0
1
1
Versatile EMI Reduction IC
Notice: The information in this document is subject to change without notice.
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