September 2003
ASM3P2811A/B
ASM3P2812A/B
ASM3P2814A/B
rev 1.0
Low Power EMI Reduction IC
Features
FCC approved method of EMI attenuation.
Provides up to 15dB EMI reduction.
Generates a 1X, 2X and 4X low EMI spread
spectrum clock of the input frequency.
o
o
o
to 40 MHz.
o
o
o
ASM3P2811A/B: 10 to 40MHz
ASM3P2812A/B: 10 to 40MHz
ASM3P2814A/B: 10 to 40MHz
1X: ASM3P2811A/B
2X: ASM3P2812A/B
4X: ASM3P2814A/B
deviation range from 鹵0.625% to 鈥?.50%.
The ASM3P28XX reduces electromagnetic interference
(EMI) at the clock source, allowing system wide reduction
of EMI of
down stream clock and data dependent
signals. The ASM3P28XX 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 ASM3P28XX modulates the output of a single PLL in
order to 鈥渟pread鈥?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鈥檚 bandwidth is called 鈥榮pread
spectrum clock generation鈥?
The ASM3P28XX uses the most efficient and optimized
modulation profile approved by the FCC and is
implemented in a proprietary all-digital method.
Optimized for input frequency range from 10MHz
Internal loop filter minimizes external components
and board space.
Selectable spread options: Down Spread and
Center Spread.
8 spread frequency deviation selections:
o
鹵0.625% to 鈥?.5%
Low inherent cycle-to-cycle jitter.
3.3V operating voltage range.
CMOS/TTL compatible inputs and outputs.
Pinout
compatible
with
Cypress
CY25811,
CY25812 and CY25814.
Products are available for industrial temperature
range.
Available in 8-pin SOIC and TSSOP.
Applications
The ASM3P28XX 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.
Product Description
The ASM3P28XX devices are versatile spread spectrum
frequency modulators designed specifically for a wide
range of input clock frequencies from 10MHz to 40MHz.
(Refer Input/Output Frequency Range Selection Table).
The ASM3P28XX can generate an EMI reduced clock
from
crystal, ceramic resonator, or system clock. The
of
spread
options
and
percentage
ASM3P28XX-A and the ASM3P28XX-B offer various
combinations
deviations (Refer
Output Frequency Deviation and
Spread Option Selection Table).
These combinations
include Down and Center Spread and percentage
Alliance Semiconductor
2575, Augustine Drive
鈥?/div>
Santa Clara, CA
鈥?/div>
Tel: 408.855.4900
鈥?/div>
Fax: 408.855.4999
鈥?/div>
www.alsc.com
Notice: The information in this document is subject to change without notice.
1
2
3
4
5
6
7
8
