I2042A-08TR Ver la hoja de datos (PDF) - Alliance Semiconductor

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I2042A-08TR

LCD Panel EMI Reduction IC

Alliance Semiconductor 

August 2005

P2042A

rev 1.3

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, P2042A is designed for high-resolution, flat panel applications and is able to support an XGA (1024 x 768) flat

panel operating at 65MHz (FIN) clock speed. A spreading selection of CP0=0, CP1=1 and SR0=0 provides a percentage

deviation of ±1.00% from FIN. This results in the frequency on ModOUT being swept from 65.65 to 64.35MHz at a modulation

rate of 101.54KHz. 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

65MHz from graphics accelerator

1 CLKIN

VDD 8

2 CP0

3 CP1

SR0 7

ModOUT 6

4 VSS

SSON# 5

P2042A

0.1µF

+3.3V

Modulated 65MHz signal with

±1.00% deviation and

modulation rate of 101.54KHz.

This signal is connected back to

the spread spectrum input pin

(SSIN) of the graphics

accelerator.

Digital control for the SS enable

or disable

LCD Panel EMI Reduction IC

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

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