ASM3P2183A Datasheet, PDF (1/8 Pages) Alliance Semiconductor Corporation – EMI Reduction IC

September 2003
ASM3P2183A
rev 1.0
EMI Reduction IC
Features
FCC approved method of EMI attenuation.
Provides up to 15dB EMI reduction.
Generates a 1X low EMI spread spectrum clock of
the input frequency.
Input frequency range: 6MHz to 103MHz.
Internal loop filter minimizes external components
and board space.
Selectable spread options: Down and Center
Spread
2 spread frequency deviation selections:
o -1.25% or ± 0.42%
Low inherent cycle-to-cycle jitter.
3.3V operating voltage range.
Low power CMOS design.
Supports notebook VGA and other LCD timing
controller applications.
Products are available for industrial temperature
range.
Available in 8-pin SOIC and TSSOP.
Product Description
The ASM3P2183 is a versatile spread spectrum
frequency modulators designed specifically for a wide
range of input clock frequencies from 6MHz to 103MHz.
(Refer Input Frequency and Modulation Rate Table). The
ASM3P2183A can generate an EMI reduced clock from
an OSC or a system generated clock. The ASM3P2183A
offers a Down Spread clock with a percentage deviation
of -1.25% and a Center Spread clock with a percentage
deviation of ± 0.42%.
The ASM3P2183A reduces electromagnetic interference
(EMI) at the clock source, allowing system wide reduction
of EMI of down stream clock and data dependent
signals. The ASM3P2183A 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 ASM3P2183A uses the most efficient and optimized
modulation profile approved by the FCC and is
implemented in a proprietary all digital method.
The ASM3P2183A 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’.
Applications
The ASM3P2183A is targeted towards 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 • Santa Clara, CA • Tel: [phone] • Fax: [phone] • www.alsc.com
Notice: The information in this document is subject to change without notice.