November 2003

P2010A

rev F

Low Frequency EMI Reduction IC

3 of 9

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 CLKIN, Pin 1).

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

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

33.33 KHz (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.

P2010 Application Schematic for Flat-Bed Scanner