November 2006

ASM3P18S19B

rev 2.2

Notice: The information in this document is subject to change without notice.

PulseCore Semiconductor Corporation

1715 S. Bascom Ave Suite 200, Campbell, CA 95008

• Tel: 408-879-9077 • Fax: 408-879-9018

www.pulsecoresemi.com

Notebook LCD Panel EMI Reduction IC

Features

•

FCC approved method of EMI attenuation.

•

Provides up to 15dB EMI reduction.

•

Generates a low EMI Spread Spectrum clock and a

non-spread reference clock of the input frequency.

•

Optimized for Frequency range from 20 to 40MHz.

•

Internal loop filter minimizes external components and

board space.

•

Low Inherent Cycle-to-Cycle jitter.

•

Two spread % selections: -1.25% to -1.75%.

•

3.3V Operating Voltage.

•

Low power CMOS design.

•

Supports notebook VGA and other LCD timing

controller applications.

•

Power Down function for mobile application.

•

Available in Commercial temperature range.

•

Available in 8-pin SOIC and TSSOP Packages.

•

RoHS Compliant

Product Description

The ASM3P18S19B is a Versatile Spread Spectrum

Frequency Modulator designed specifically for input clock

frequencies from 20 to 40MHz. (Refer Input Frequency and

Modulation Rate Table). The ASM3P18S19B reduces

electromagnetic interference (EMI) at the clock source,

allowing system wide reduction of EMI of down stream

clock and data dependent signals. The ASM3P18S19B

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 ASM3P18S19B 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 ASM3P18S19B uses the most efficient and optimized

modulation profile approved by the FCC and is

implemented in a proprietary all digital method.

Applications

The ASM3P18S19B 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.

Block Diagram

VSS

VDD

ModOUT

XIN/CLKIN

Frequency

Divider

Feedback

Divider

Modulation

Phase

Detector

Loop

Filter

VCO

Output

Divider

PLL

SRS

PD#

Crystal

Oscillator

XOUT

REF