Low Power EMI Reduction IC
FCC approved method of EMI attenuation.
Provides up to 15dB EMI reduction.
Generates a 4X REF EMI spread output
Spectrum clock of the input frequency.
Optimized for input frequency range from
10 to 20MHz.
External Loop Filter for configurability and
flexibility in application and design (spread
Power Down Mode
Very Low Cycle-to-Cycle Jitter.
3.3V operating Range
CMOS / TTL compatible inputs and outputs
Available in 8-pin SOIC and 8-pin TSSOP
The ASM3P2109A device is a versatile spread spectrum
Frequency Synthesizer / Modulator designed specifically
for a wide Range of input clock frequencies from 10MHz to
20MHz with a 4X multiplier for output clock frequencies
from 40MHz to 80 MHz.
The ASM3P2109A generates an EMI reduced clock signal
from a crystal, ceramic resonator, or system clock. The
ASM3P2109A generates a range of modulation rates and
deviations (spread) from Center Frequency based upon the
input frequency, and is set / determined via an external
filter network ( see Loop Filter Selection table )
The ASM3P2109A reduces Electro Magnetic Interference
(EMI), at the Clock Source, allowing system wide reduction
of EMI on downstream clock and data dependant signals.
The ASM3P2109A modulates the output of a single
PLL in order to “spread” the bandwidth of a
synthesized clock, thereby decreasing the Peak
amplitudes of its associated harmonics. This results
in significantly lower radiated EMI compared to the
narrow band signal produced by standard oscillators
and most clock synthesizers & generators. This
technique of lowering EMI by increasing the signals
bandwidth is called Spread Spectrum Clocking
(SSC). The ASM3P2109A utilizes the most efficient
and optimized modulation profile approved by the
FCC, and is implemented using a proprietary, All-
The resulting EMI reduction provides for significant cost
savings by reducing the number of circuit board layers and
shielding that are traditionally associated with designs in
order to achieve EMI regulatory compliance.
The ASM3P2109A is targeted towards the Consumer
and PC/Data Processing, or Computation markets.
Entertainment devices, LCD displays, Notebook
computers, PC peripheral devices, embedded
systems, PDA’s, and hand held devices provide a
platform to take full advantage of the feature set of
2575, Augustine Drive Santa Clara, CA Tel: 408.855.4900 Fax: 408.855.4999 www.alsc.com
Notice: The information in this document is subject to change without notice.