P2811A/B and P2812A/B and P2814A/B

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

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.