I2041AF-08SR Просмотр технического описания (PDF) - ON Semiconductor

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I2041AF-08SR

Versatile EMI Reduction IC

ON Semiconductor 

P2041A

Table 3. SPREAD RANGE SELECTION

SR1

SR0

Spreading Range

0

0

±1.50%

0

1

±2.50%

1

0

±0.50%

1

1

±1.00%

Modulation rate

(Fin/40)*34.72 KHz

(Fin/40)*34.72 KHz

(Fin/40)*34.72 KHz

(Fin/40)*34.72 KHz

Spread Spectrum Selection

Table 3 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 40 MHz:

A spreading selection of SR1=1 and SR0=1 provides a

percentage deviation of ±1.00%* (see Table 3) of Center

Frequency. This results in the frequency on ModOUT being

swept from 40.40 MHz to 39.60 MHz at a modulation rate

of (40/40)*34.72 = 34.72 KHz (see Table 3). 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.

40 MHz

1 XIN / CLK VDD 8

2 XOUT

SR0 7

3 SR1 ModOUT 6

4 VSS

SSON 5

P2041A

VDD

0.1 mF

Modulated 40 MHz signal with ±1.00%

Deviation and modulation rate of

34.72 KHz. 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 set-

ting (no connection on pin 3, 7 and 5).

Figure 2. P2041A Application Schematic for Flat−Bed Scanner

http://onsemi.com

3

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