November 2006

P2010A

rev 0.2

Low Frequency EMI Reduction IC

3 of 8

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

Spread Spectrum Selection

Table 1 illustrates 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 XIN/CLK, Pin 1).

Example of a typical printer or scanner application that operates on a clock frequency of 16MHz:

A spreading selection of FS0=1 and SR0=1 provides a percentage deviation of +/-2.50%* (see Table 1) of Center

Frequency. This results in the frequency on ModOUT being swept from 16.40MHz to 15.60MHz at a modulation rate of

33.33KHz (see Table 1). This particular example (see Figure below) given here is a common EMI reduction method for

scanner, printer or embedded applications and has already been adopted by most of the leading manufacturers.

Note: Spreading range selection varies from different system manufacturers and their designs.

P2010A Application Schematic for Flat-Bed Scanner

1

2

3

4

8

7

6

5

VDD

SR0

ModOUT

SSON

VSS

FS0

XOUT

XIN/CLK

P2010A

VDD

Connected to CLK input pin of the system

16MHz Crystal Input

0.1µF