P2811A/B and P2812A/B and P
Low Power EMI Reduction IC
©2010 SCILLC. All rights reserved. Publication Order Number:
JUNE 2011 – Rev. 2 P2811/D
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 1x: P2811A/B
o 2x: P2812A/B
o 4x: P2814A/B
• Optimized for input frequency range from 10MHz to
40MHz
• Internal loop filter minimizes external components
and board space
• Selectable spread options:
o Down Spread and Center Spread
• 8 frequency deviation selections:
o ±0.625% to -3.5%
• Low inherent Cycle-to-Cycle Jitter
• 3.3V Operating Voltage
• CMOS/TTL compatible inputs and outputs.
• Pin-out compatible with Cypress CY25811, CY25812
and CY25814
•
Available in 8-pin SOIC Package
Product Description
The P28XX devices are versatile spread spectrum
frequency modulators designed specifically for a wide
range of input clock frequencies from 10MHz to 40MHz.
Refer to Input/output Frequency Range Selection Table.
The P28XX can generate an EMI reduced clock from
crystal, ceramic resonator, or system clock. The P28XX-A
and the P28XX-B offer various
combinations of spread options and percentage
deviations. Refer to Frequency Deviation and Spread
Selection Table. These combinations include Down and
Center Spread, and percentage deviation range from
±0.625% to -3.5%.
The P28XX reduces electromagnetic interference (EMI)
at the clock source, allowing system wide reduction of
EMI of downstream clock and data dependent signals.
The P28XX 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 P28XX 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’.
The P28XX uses the most efficient and optimized
modulation profile approved by the FCC and is
implemented in a proprietary all-digital method.
Applications
The P28XX 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.
