ASM3P2182A Datasheet, PDF (1/6 Pages) Alliance Semiconductor Corporation – LCD Panel EMI Reduction IC

ASM3P2182A
LCD Panel 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: 25MHz to 210MHz.
• Internal loop filter minimizes external components
and board space.
• Center spread.
• 4 spread frequency deviation selections: ± 0.13% to
± 1.24%.
• Low inherent Cycle-to-cycle jitter.
• 3.3V Operating Voltage.
• TTL or CMOS compatible inputs and outputs.
• Low power CMOS design.
• Supports notebook VGA and other LCD timing
controller applications.
• Available in 8-pin SOIC Package.
Product Description
The ASM3P2182A is a versatile spread spectrum
frequency modulator designed specifically for a wide
range of input clock frequencies from 25MHz to 210MHz.
(Refer to Input Frequency and Modulation Rate Table).
The ASM3P2182A can generate an EMI reduced clock
from an OSC or a system generated clock. The
ASM3P2182A offers a Center Spread clock and with a
percentage deviation from ± 0.13% or ± 1.24%.
S0
FS0 FS1
The ASM3P2182A reduces electromagnetic interference
(EMI) at the clock source, allowing system wide
reduction of EMI of down stream clock and data
dependent signals. The ASM3P2182A 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 ASM3P2182A uses the most efficient and optimized
modulation profile approved by the FCC and is
implemented in a proprietary all digital method.
The ASM3P2182A 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 ASM3P2182A 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.
VDD
CLKIN
Crystal
Oscillato
r
Frequency
Divider
Feedback
Divider
Modulation
Phase
Detector
Loop
Filter
PLL
VCO
Output
Divider
ModOUT
©2010 SCILLC. All rights reserved.
JANUARY 2010 – Rev. 2
VSS
Publication Order Number:
ASM3P2182/D