IMIFS741 データシートの表示（PDF） - Unspecified

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IMIFS741

Low EMI Spectrum Spread Clock

Unspecified 

Approved Product

FS741

Low EMI Spectrum Spread Clock

Figure 11 shows the modulation profile of the FS741. This type of test is done with a time domain analyzer. What

this shows is the amount of time that the clock spends at any one frequency within its modulation envelope. From

this type of picture, the amount of modulation percentage and modulation rate can be determined. This picture

shows that the FS741 is modulating 2% around the 10 MHz input and the modulation rate is 83.06 KHz.

APPLICATION NOTES AND SCHEMATICS

The schematic diagram shown below is a simple minimum component application example of an FS741 design.

Note: C3 and C4 values assume a first order crystal with CL = 17 pF.

Figure 12.

27 pf.

C3

XTAL

27 pf.

VDD

C4

50 K

R1

C1

U?

1 Xin

2 Xout

3 Ref_Off

4 LF

C2

VDD

VDD 8

Refout/RS0 7

Modout/RS1 6

VSS 5

FS741

C5

0.1 uF.

R3

10

C6

4.7 uF.

33

33

R2

FREQUENCY SELECTION TABLE

XIN INPUT RANGE

RS1

RS0

4 - 8 MHz

0

0

8 - 16 MHz

0

1

16 - 40 MHz

1

0

40 - 68 MHz

1

1

.

RS1 RS0

REFER TO FREQUENCY TABLE

Connect to VCC, not VDD, when

logic "1" is required.

Use 4.7K if R2 or R3 is logic “0”

(pulled-down to VSS) and use

2.2K if R2 or R3 is logic “1”

(pulled-up to VCC).

VCC

Refout

Modout

International Microcircuits, Inc.

525 Los Coches St., Milpitas, 95035 408-263-6300, FAX 408-263-6571

http:/www.imicorp.com

4/5/1999

Rev. 2.1

Page 14 of 16

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