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PDF IMISM532 Data sheet ( Hoja de datos )
| Número de pieza | IMISM532 | |
| Descripción | Low EMI Spectrum Spread Clock | |
| Fabricantes | International Microcircuits | |
| Logotipo |  |
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YJGP VKOKPI KU ETKVKECN
Approved Product
SM532
Low EMI Spectrum Spread Clock
FEATURES
• Reduces Systemic EMI.
• Modulates external source clock.
• 3 - 5 Volt power supply.
• 14 to 120 MHz.operating frequency range.
• Output is multiplied or divided by 1, 2 or 4.
• Digitally controlled modulation.
• TTL/CMOS compatible outputs.
• Fout modulation centered around reference.
• Compliant with all major CISC, RISC and
DSP processors.
• Low short term jitter.
• Synchronous output enable.
• Power down mode for low current operation.
• Available in 16 pin SOIC package.
APPLICATIONS
• Desktop/Laptop Computer
• Modems
• Scanners, Printers, Copiers, Fax Machines, MFP’s
• Disk and CD-ROM Drives
• Automotive and EmbeddedSystems
• Networking, LAN/WAN
• Digital Cameras, Games
• LCD displays
BENEFITS
• Time to Market
• Lower cost of compliance
• Programmable EMI reduction
• No degradation in Rise/Fall times
• Lower component and PCB layer count
GENERAL DESCRIPTION
The IMI SM532 is a Spectrum Spread Clock Modulator designed for the purpose of reducing the Electro- Magnetic
Interference (EMI) found in today’s high speed digital systems. The SM532 is well suited for a wide range of digital
system applications that require a reduction of radiated energy. This unwanted radiated energy is usually found in
the odd harmonics of digital system clocks. By modulating the frequency of the digital clock, measured EMI at the
fundamental and harmonic frequencies is greatly reduced. This reduction in radiated energy can significantly
reduce the cost of complying with regulatory requirements and time to market, without degrading clock and timing
signals.
The IMI SM532 is extremely versatile and flexible in that program control is available for each of the operating
modes. Program control is provided for Input Frequency, Output Frequency Multiplication, Output Bandwidth,
Modulation ON/OFF and Fout state during Power Down Mode.
Depending on the range of operation, the output clock, Fout, can be a multiple (1, 2, 4) or a division (1, 1/2, 1/4) of
the input frequency. The power-down mode adds the flexibility of operating in a completely static mode for reduced
standby current and simplified system board testing.
There are many benefits to using the SM532 Low EMI Clock Modulator. The most important benefit is reducing
the amount of clock related EMI by as much as 12 - 18 dB, depending on the application. SM532 is available with
only Center-Spread frequency modulation. Refer to SM530 for Down-Spread frequency modulation and other
functions.
International Microcircuits,Inc.
525 Los Coches St., Milpitas, 95035 408-263-6300, FAX 408-263-6571
http:/www.imicorp.com
8/31/98
Rev. 1.4
Page 1 of 14
1 page  
+/+
YJGP VKOKPI KU ETKVKECN
Approved Product
SM532
Low EMI Sprectum Spread Clock
Timing Characteristics
Characteristic
Symbol
Min
Typ Max Units
Output Rise Time Measured at 10% - 90% @ 5 VDC
tTLH
3.3
3.5
3.8 ns
Output Fall Time Measured at 10% - 90% @ 5 VDC
tTHL
2.1
2.3
2.5 ns
Output Rise Time Measured at 0.8V - 2.0V @ 5 VDC
tTLH
0.7
0.75
0.8 ns
Output Fall Time Measured at 0.8V - 2.0 V @ 5 VDC
tTHL
0.6
0.7
0.8 ns
Output Rise Time Measured at 10% - 90% @ 3.3 VDC
tTLH
4.8
5.0
5.4 ns
Output Fall Time Measured at 10% - 90% @ 3.3 VDC
tTHL
2.9
3.2
3.4 ns
Output Rise Time Measured at 0.8V - 2.0V @ 3.3 VDC
tTLH
1.6
1.75
1.9 ns
Output Fall Time Measured at 0.8V - 2.0 V @ 3.3 VDC
tTHL
1.1
1.3
1.5 ns
Output Duty Cycle
TsymF1
45
50
55 %
Peak-to Peak Jitter One Sigma (SSON = 1)
tj1s - 250 500 ps
Measurements performed at VDD = 3.3V +/-5% and 5V +/-10%, TA = 0°C to 70°C, CL = 15pF, Fout = 50.0 MHz.
Table 4.
FREQUENCY SELECTION TABLE
The following table provides the necessary information for setting the control lines for proper operation of the
SM532 and for any frequency within its operating range. Note that the table includes operating frequencies at 3.3
and 5.0 VDC. The 3.3 VDC columns are lower in frequency than the 5.0 VDC operation due to the characteristics
of the VCO.
VDD = 5
Fin (Range)
(MHz)
MIN MAX
See
14 30
14 30
14 30
Volts
Fout/
Fin
X
Note
1
2
4
+/- 10%
Fout (Range)
(MHz)
MIN MAX
14 30
28 60
56 120
Multiplier
Settings
S1 S0
00
01
10
11
Input Range
Settings
R1 R0
XX
01
01
01
VDD = 3.3
Fin (Range)
(MHz)
MIN MAX
See
14 22.5
14 22.5
14 22.5
Volts
Fout/
Fin
X
Note
1
2
4
+/- 5%
Fout (Range)
(MHz)
MIN MAX
14 22.5
28 45
56 90
30 60 0.5 15 30 0 1 1 0 25 45 0.5 12.5 22.5
30 60
1 30 60
101
0 25 45 1
25 45
30 60
2 60 120 1 1 1
0 25 45 2
50 90
60 120 0.25 15 30
011
1 50 90 0.25 12.5 22.5
60 120 0.5 30 60
101
1
50 90 0.5
25
45
60 120 1 60 120 1 1 1
1 50 90 1
50 90
Note: Selects Power Down state, see table 7. X = don’t care condition.
Table 5. Frequency Selection Table
International Microcircuits,Inc.
525 Los Coches St., Milpitas, 95035 408-263-6300, FAX 408-263-6571
http:/www.imicorp.com
8/31/98
Rev. 1.4
Page 5 of 14
5 Page 
+/+
YJGP VKOKPI KU ETKVKECN
Approved Product
SM532
Low EMI Sprectum Spread Clock
Modulation Profile
The SM532 moves from max. to min. frequencies of its bandwidth at a pre-determined rate and profile. The
modulation frequency is determined by the input frequency and an internal divider. All 3 operating ranges
modulate the Fout clock at from 20 to 40 kHz. The three operating ranges are 14 - 30 MHz, 30 - 60 MHz and 60
to 120 MHz. If OSCin = 15 MHz, the modulation rate is 20 kHz. If OSCin is 60 MHz, in mid-range, the modulation
rate would be 40 kHz. To provide the proper modulation rate the input reference frequency is divided by a fixed
number in each range. The input reference frequency is divided by 750 in Low Range, 1500 in Mid Range and
3000 in the High Range. From these numbers, the modulation rate can be determined for any input frequency.
Example:
OSCin = 45.378 MHz, Input Range = Mid, Input divisor = 1500
Fmod = OSCin /1500
Fmod = 30.252 kHz
If you have a clock frequency that was on the boundary of the Mid-range and the High range of operation, the
choice of selecting which range to use would be determined by which modulation rate is desired. If you choose
the Mid-range, the modulation rate would be 40 kHz, while choosing the High range would yield a 20 kHz
modulation rate. There is some operational overlap between ranges, such that 58 MHz in the Mid-Range would
give the same results as 58 MHz in the High-Range, except for the modulation rate. This type of operation is not
recommended unless it is thoroughly tested.
The modulation profile of the SM532 is not a linear sweep from max to min and back. The OSCin reference clock
determines the modulation frequency but the internal SSCG control logic determines the actual modulation profile.
The modulation profile can best be described by comparing the instantaneous frequency at Fout with time. The
illustration in figure 9 below is a representation of the modulation profile of the SM532 as displayed on a Time
Domain Analyzer.
50.625
50.468
+1.25%
50.312
2.5%
50.156
50.000
49.844
49.687
-1.25%
49.531
49.375
Fmax
Fcenter
Fmin
0 5 10 15 20 25
Time (microseconds)
Figure 8. Frequency Profile in Time Domain
30
35
International Microcircuits,Inc.
525 Los Coches St., Milpitas, 95035 408-263-6300, FAX 408-263-6571
http:/www.imicorp.com
8/31/98
Rev. 1.4
Page 11 of 14
11 Page | ||
| Páginas | Total 14 Páginas | |
| PDF Descargar | [ Datasheet IMISM532.PDF ] | |
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