I2041A-8TT
| Model | I2041A-8TT |
| Description | Clock Generator, 40.4MHz, CMOS, PDSO8, 4.40 MM, TSSOP-8 |
| PDF file | Total 9 pages (File size: 177K) |
| Chip Manufacturer | PULSECORE |
January 2006
rev 0.1
Spread spectrum selection
P2041A
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 40MHz:
A spreading selection of SR1=1 and SR0=1 provides a percentage deviation of +/-1.00%* (see Table 1) of Center
Frequency. This results in the frequency on ModOUT being swept from 40.40MHz to 39.60MHz at a modulation rate of
(40/40)*34.72 = 34.72KHz (see Table 1). This particular example (see Figure below) given here is a common EMI reduction
method for scanners and has already been implemented by most of the leading manufacturers.
NOTE:
Spreading range selection varies from different system manufacturers and their designs. The spreading range of P2041A can be set to +/-2.5% when
working with certain scanner model.
P2041A Application Schematic for Flat-Bed Scanner
40MHz
1 XIN/CLK
2 XOUT
3 SR1
4 VSS
VDD 8
SR0 7
0.1µF
VDD
Modulated 40MHz signal with ± 1.00%
Deviation and modulation rate of
34.72KHz. This signal is connected back
to the clock crystal Input pin of the
system ASIC.
NOTE: The above schematic indicates
The exact setting of this example:
Default setting (no connection on pin 3,
7 and 5)
ModOUT 6
SSON 5
P2041A
Versatile EMI Reduction IC
Notice: The information in this document is subject to change without notice.
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