range.
鈥?/div>
Product Description
The P18xx is a versatile spread spectrum frequency
modulator designed specifically for a wide range of input
clock frequencies from 10 to 160 MHz (see Input Fre-
quency and Modulation Rate Selections). The P18xx
can generate an EMI reduced clock from crystal,
ceramic resonator, or system clock. The P18xx-A to
P18xx-H offer various combinations of spread options
and percentage deviations (see Spread Deviation Selec-
tions). These combinations include Down Spread,
Center Spread and percentage deviation range from
卤0.625% to -3.50%.
The P18xx reduces electromagnetic interference (EMI)
at the clock source, allowing a system wide EMI
reduction for all the down stream clocks and data
dependent signals. The P18xx allows significant system
cost savings by reducing the number of circuit board
layers, ferrite beads, shielding, and other passive
components that are traditionally required to pass EMI
regulations.
The P18xx modulates the output of a single PLL in
order to 鈥渟pread鈥?the bandwidth of a synthesized clock,
thereby decreasing 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 clock generators.
Lowering EMI by increasing a signal鈥檚 bandwidth is
called 鈥渟pread spectrum clock generation鈥?
The P18xx uses the most efficient and optimized
modulation profile approved by the FCC and is
implemented by using a proprietary all-digital method.
Applications
The P18xx is targeted toward EMI management for
memory and LVDS interfaces in mobile graphic
chipsets and high-speed digital applications such as
PC peripheral devices, consumer electronics, and
embedded controller systems.
Alliance Semiconductor
2575 Augustine Drive 鈥?Santa Clara, CA 95054 鈥?Tel: 408.855.4900 鈥?Fax: 408.855.4999 鈥?www.alsc.com
Notice: The information in this document is subject to change without notice.
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