Alliance Semiconductor
Product Proposal
AS80M2183/84
Jul., 2003 PulseCore – A Division of Alliance Semiconductor
Revision A 3160 De La Cruz Blvd., Suite 200 • Santa Clara • CA • 95054
Tel (408) 748-6988 • Fax (408) 748-0009
1 of 5
http://www.alsc.com
®
EMI Reduction IC
FEATURES
• FCC approved method of EMI attenuation
• Provides up to 15 dB EMI reduction
• Generates a 1X low EMI spread spectrum
clock from the input frequency
• Optimized for frequency range:
AS80M2183/84: 6 MHz to 70 MHz
• Internal loop filter minimizes external
components and board space
• AS80M2183: Down Spread
AS80M2184: Center Spread
• Low inherent cycle-to-cycle jitter
• 2 spread % selections:
AS80M2183: - 1.25% or – 3.75%
AS80M2184: +/- 0.625% or +/- 1.875%
• 3.3V operating voltage
• CMOS/TTL compatible inputs and outputs
• 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 AS80M2183/84 is a versatile spread spectrum
frequency modulator designed specifically for a
wide range of input clock frequencies from 6 to 70
MHz (see Table 1). The AS80M2183/84 can
generate an EMI reduced clock from an OSC or a
system generated clock.
The AS80M2183/84 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
AS80M2183/84 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 AS80M2183/84 modulates the output of a
single PLL in order to “spread” 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’s bandwidth is called “spread
spectrum clock generation”.
The AS80M2183/84 uses the most efficient and
optimized modulation profile approved by the FCC
and is implemented by using a proprietary all-
digital method.
APPLICATIONS
The AS80M2183/84 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.