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Teilenummer | SG528 |
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Beschreibung | Spread Spectrum Clock Generator | |
Hersteller | INTERNATIONAL MICROCIRCUITS | |
Logo | ||
Gesamt 12 Seiten Approved Product
Features
• Generates Spread Spectrum Clock (SSC)
• Programmable Frequencies from 10 to 120 MHz
• 1.25% and 3.25% Down-Spread Options
• Separate Non-Modulated Clock
• Pin-Programmable Spread on/off Function
• 50% Output Clock Duty Cycle
• Power-Down Mode for Low Power Dissipation
• TTL or CMOS Compatible Outputs
• Low Cycle-to-Cycle Jitter of 250 ps-max
• External Clock or Crystal Oscillator Operation
• Glitch-Free Switching
• 3 to 5V Operation Supply Range
• 16-Pin Plastic SOIC Package
SG521/22/24/28
Spread Spectrum Clock Generator
Applications
• CPU and µC Based Digital Systems
• Laser and Inkjet Printers
• Digital Copiers
• Multifunction Products (MFPs)
• Disk Drives
• CD-ROM
• Automotive
• Video and Imaging Applications
Benefits
• 12 to 20dB EMI Reduction
• Fast Time to Market
• Low System and Development Cost
General Description
IMI SG521/22/24/28 products are Spread Spectrum Clock Generators designed to reduce the high levels of
Electromagnetic Interference (EMI) found in high-speed digital systems.
By using a modulated clock as the source for all system clocks and timing signals, the amount of radiated energy
(EMI) throughout the system is greatly reduced. Energy reduction is related to the harmonic frequency, such that
the higher the frequency the greater the energy reduction. The 5th harmonic has greater energy reduction than the
fundamental frequency.
The SG521/2/4/8 products produce a wide range of clock frequencies from 10 to 120 MHz, which are frequency
modulated (PRCLK) by using a Spread Spectrum Clock (SSC) technique to reduce electromagnetic interference
(EMI). In addition, a non-modulated clock output (MPCLK) with various standard clock frequencies is also provided
for the part of the system that could be sensitive to a modulated clock. Refer to the Product Selection and
Frequency Selection Truth Tables for the available modulated and non-modulated clock frequencies.
The spread function can be turned on or off using the SSON control line. When spread is enabled, the modulated
output clock is down-spread at either 1.25% or 3.25% total spread.
These products are designed to be used with fixed frequency external clocks or crystal oscillators. The output clock
frequencies are designed using a 14.318, 44.24 or 48 MHz reference clock.
The products operate from a 3 to 5 volt power supply and 0 to 70°C temperature range. The SG521/2/4/8 parts are
available in 16-pin plastic SOIC packages and in die form.
Contact IMI for other packaging and Spread Spectrum Clock Generator (SSCG) products.
INTERNATIONAL MICROCIRCUITS,INC. 525 LOS COCHES ST.,
MILPITAS, CA 95035 408-263-6300, FAX 408-263-6571
http:/www.imicorp.com
Rev. 2.0
5/25/2000
Page 1 of 12
Approved Product
Modulation Rate Calculation
SG521/22/24/28
Spread Spectrum Clock Generator
The input frequency, Fin, at pin 2 (OSCin) and the correlating formula determine the modulation rate, Fmod, of the
SG52x series. Refer to the formulae below:
If OSCin = 14.318 MHz, then;
If OSCin = 48.00 MHz, then;
If OSCin = 44.24 MHz, then;
Fmod = OSCin/(4 x 114) =
Fmod = OSCin/(12 x 114) =
Fmod = OSCin (48/44.24)/(12 x144) =
31.40kHz
35.09kHz
35.09kHz
SG521 Frequency and Spread Selection Truth Table
TEST "0" MPCLK(S3)
(pin 16) "1" (pin 14)
PRCLK(S2) SS_SEL "1" S4 "1"
"1" (pin 12) (pin 10) (pin 5)
S1 "0" S0 "0" OSCin.(MHz) PRCLK (MHz) SPREAD
(pin 8) (pin 7) (pin 2)
(pin 12) 1.25% 3.25%
00
00
00
00
0
X
X
0
0
44.24
16.685345
0
X
X
0
1
44.24
40.044828
0
X
X
1
0
44.24
25.028017
0
X
X
1
1
44.24
30.033621
•
•
•
•
00
00
00
00
00
00
00
00
01
01
01
01
01
01
01
01
01
01
01
01
01
01
01
01
1
0
X
0
0
14.318
10.001544
•
1
0
X
0
1
14.318
20.003088
•
1
0
X
1
0
14.318
25.003860
•
1
0
X
1
1
14.318
50.007721
•
1
1
X
0
0
14.318
10.001544
•
1
1
X
0
1
14.318
20.003088
•
1
1
X
1
0
14.318
25.003860
•
1
1
X
1
1
14.318
50.007721
•
0 0 X 0 0 48 10.000000
•
0 0 X 0 1 48 20.000000
•
0 0 X 1 0 48 25.000000
•
0 0 X 1 1 48 50.000000
•
0
1
X
00
48
10.000000
•
0
1
X
01
48
20.000000
•
0
1
X
10
48
25.000000
•
0
1
X
11
48
50.000000
•
1
0
X
0
0
44.24
10.011207
•
1
0
X
0
1
44.24
20.022414
•
1
0
X
1
0
44.24
25.028017
•
1
0
X
1
1
44.24
50.056034
•
1
1
X
0
0
44.24
10.011207
•
1
1
X
0
1
44.24
20.022414
•
1
1
X
1
0
44.24
25.028017
•
1
1
X
1
1
44.24
50.056034
•
1X
1X
1X
1X
X
X
X
00
N/A
0 (PD)
N/A
X
X
X
01
N/A
1 (PD)
N/A
X
X
X
10
N/A
TEST
N/A
X
X
X
11
N/A
Hi-Z
N/A
Table 2.
INTERNATIONAL MICROCIRCUITS,INC. 525 LOS COCHES ST.,
MILPITAS, CA 95035 408-263-6300, FAX 408-263-6571
http:/www.imicorp.com
Rev. 2.0
5/25/2000
Page 6 of 12
6 Page Approved Product
Notes:
SG521/22/24/28
Spread Spectrum Clock Generator
NOTICE
International Microcircuits, Inc. reserves the right to make changes to its products in order to improve design,
performance or reliability. International Microcircuits, Inc. assumes no responsibility for the use of its products in life
supporting and medical applications where the failure or malfunction of the product could cause failure of the life
supporting and medical systems. Products are not authorized for use in such applications unless a written approval
is requested by the manufacturer and an approval is given in writing by International Microcircuits, Inc. for the use
of its products in the life supporting and medical applications.
INTERNATIONAL MICROCIRCUITS,INC. 525 LOS COCHES ST.,
MILPITAS, CA 95035 408-263-6300, FAX 408-263-6571
http:/www.imicorp.com
Rev. 2.0
5/25/2000
Page 12 of 12
12 Page | ||
Seiten | Gesamt 12 Seiten | |
PDF Download | [ SG528 Schematic.PDF ] |
Teilenummer | Beschreibung | Hersteller |
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