October 2003
P2160
rev E
Table-1 Modulation Selection
FS0
0
0
0
0
1
1
1
1
MRA
SR0
0
1
0
1
0
1
0
1
Frequency Range
40-80MHz
Spread Range
+/- 0.5%
Modulation Rate
0
0
1
1
0
0
1
1
(Fin/40) * 34.72 KHz
(Fin/40) * 34.72 KHz
(Fin/40) * 20.83 KHz
(Fin/40) * 20.83 KHz
(Fin/80) * 34.72 KHz
(Fin/80) * 34.72 KHz
(Fin/80) * 20.83 KHz
(Fin/80) * 20.83 KHz
40-80MHz
40-80MHz
40-80MHz
80-166MHz
80-166MHz
80-166MHz
80-166MHz
+/- 1.0%
+/- 0.5%
+/- 1.0%
+/- 0.5%
+/- 1.00%
+/- 0.5%
+/- 1.00%
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: P2160 is designed for high-resolution flat panel applications and is able to support UXGA (1600 X
1200) flat panel that operates on 162 MHz (Fin) clock speed. A spreading selection of FS0=1, SR0=1 and
modulation rate selection MRA=1, enables input frequency range from 80 ~ 166 MHz and provides a
percentage deviation of +/-1.00% (see Table 1) of the input frequency (Fin). This results in frequency on
ModOUT being swept from 160.38 MHz to 163.62 MHz at a modulation rate of 42.18 KHz (162 MHz/80 MHz X
20.83KHz). This particular example (see below figure) given here is a common EMI reduction method for
notebook and LCD monitor manufacturers and has already been implemented by most of the leading OEM and
mobile graphic accelerator manufacturers.
Application Schematic for Mobile LCD Graphics Controllers
High Frequency LCD Panel EMI Reduction IC
3 of 9
Notice: The information in this document is subject to change without notice.
ALSC [ ALLIANCE SEMICONDUCTOR CORPORATION ]
