October 2005

P2040A

rev 1.2

LCD Panel EMI Reduction IC

4 of 9

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

Spread Spectrum Selection

The Modulation Selection Table defines the possible spread spectrum options. The optimal setting should minimize system

EMI to the fullest without affecting system performance. The spreading is described as a percentage deviation of the center

frequency. (Note: The center frequency is the frequency of the external reference input on CLKIN, pin1).

For example, P2040A is designed for high-resolution, flat panel applications and is able to support an XGA (1024 x 768) flat

modulation rate of 56.24KHz. Refer Modulation Selection Table. The example in the following illustration is a common EMI

reduction method for a notebook LCD panel and has already been implemented by most of the leading OEM and mobile

graphic accelerator manufacturers.

Application Schematic for Mobile LCD Graphics Controllers

Modulated 65MHz signal with

±0.75 deviation and modulation

rate of 56.24KHz. This signal is

connected back to the spread

spectrum input pin (SSIN) of the

graphics accelerator.

1

2

3

4

CLKIN

MRA

SR1

VSS

SR0

5

6

7

8

SSON#

ModOUT

VDD

65MHz from graphics accelerator

+3.3V

0.1µF

P2040A

Digital control for the SS enable

or disable