November 2006
rev 0.2
Table-1 Modulation and Spreading Selection
MRA
0
0
1
1
SR0
0
1
0
1
Spread Range
Reserve
+/- 0.30%
+/- 0.20%
+/- 0.60%
Modulation Rate
Reserve
(Fin/10)*34.72 KHz
(Fin/10)*20.83 KHz
(Fin/10)*20.83 KHz
P2027A
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:
P2027 is designed for DSC and digital video and imaging markets and is optimized for 27 MHz under
minimum deviation settings. Selecting P2027’s spread options to MRA=1 and SR0=1 for a 27 MHz input signal
provides a percentage deviation of +/-0.60% (see Table 1) from the reference signal. This results in frequency
on ModOUT being swept from 27.16 MHz to 26.84 MHz at a modulation rate of 56.24 KHz (see Table 1). This
particular example (see the below figure) given here is a new EMI reduction method for DSC applications and is
already gaining popularity among leading manufacturers.
Application Schematic for Digital Still Camera
General Purpose EMI Reduction IC
Notice: The information in this document is subject to change without notice.
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