ASM3P2184A Datasheet, PDF (1/9 Pages) Alliance Semiconductor Corporation – LCD Panel EMI Reduction IC

November 2003
rev 1.0
LCD Panel EMI Reduction IC
ASM3P2184A
Features
ƒ FCC approved method of EMI attenuation.
ƒ Provides up to 15dB EMI reduction.
ƒ Generates a 1X low EMI spread spectrum clock of
the input frequency.
ƒ Input frequency range: 6MHz to 70 MHz.
ƒ Internal loop filter minimizes external components
and board space.
ƒ Spread option: Center Spread.
ƒ 2 spread frequency deviation selections:
o ±0.625% or ±1.875%
ƒ Low inherent cycle-to-cycle jitter.
ƒ 3.3V operating voltage range.
ƒ Low power CMOS design.
ƒ Supports notebook VGA and other LCD timing
controller applications.
ƒ Product available for industrial temperature range.
ƒ Available in 8-pin SOIC and TSSOP.
Product Description
The ASM3P2184A is a versatile spread spectrum
frequency modulators designed specifically for a wide
range of input clock frequencies from 6MHz to 70MHz.
(Refer Input Frequency and Modulation Rate Table). The
ASM3P2184A can generate an EMI reduced clock from
an OSC or a system generated clock. The
ASM3P2184A offers a Center Spread clock with 2
percentage deviations; ±0.625% and ±1.675%.
The ASM3P2184A reduces electromagnetic interference
(EMI) at the clock source, allowing system wide reduction
of EMI of down stream clock and data dependent
signals. The ASM3P2184A 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 ASM3P2184A uses the most efficient and optimized
modulation profile approved by the FCC and is
implemented in a proprietary all digital method.
The ASM3P2184A 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 ASM3P2184A 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.