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FEATURES
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YJGP VKOKPI KU ETKVKECN
SM532
Low EMI Spectrum Spread Clock
APPLICATIONS
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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
Approved Product
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.
BENEFITS
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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
+/+
S2
S3
R0
R1
OSCin
OSCout
11
9
14
13
1
2
YJGP VKOKPI KU ETKVKECN
SM532
Low EMI Sprectum Spread Clock
LF
Approved Product
SSON
8
SSCG
and
Power
Down
Control
5
Phase
Detector
VCO
Divide
by R
Divide
by N
4
S0
Divide by
1, 2, 4
7
S1
12
Fout
Figure 1. Block Diagram
ORDERING INFORMATION
Part No.
Package
Operating
Temperature Range
IMISM532AXB
Marking Example:
IMI
SM532AXB
Date Code, Lot#
16 Pin SOIC
0 C to 70 C
0
0
IMISM532AXB
Flow
B = Commercial, 0°C to 70°C
Package
X = SOIC
Revisions
IMI Device Number
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 2 of 14
+/+
YJGP VKOKPI KU ETKVKECN
SM532
Low EMI Sprectum Spread Clock
1
2
3
4
5
6
7
8
16
15
14
DVDD
DVSS
R0
R1
Fout
S2
DVDD
S3
Approved Product
OSCin
OSCout
AVDD
S0
LF
AVSS
S1
SSON
SM532
13
12
11
10
9
Figure 2. SOIC Package Pin Assignment
Pin Descriptions
Pin No.
1,2
Pin Name
OSCin,
OSCout
I/O
I/O
TYPE
CMOS
Description
Pins form an on-chip reference oscillator when connected to terminals
of an external parallel resonant crystal. OSCin may be connected to a
TTL/CMOS external clock source. AC coupling may be required. If
OSCin is connected to an external clock other than a crystal, leave
OSCout (pin 2) unconnected. The input frequency range is 14 to 120
Mhz @ 5.0 VDC.
Analog circuit positive power supply.
Input control used to select the frequency multiplication at Fout,
relative to the reference clock. See table on page 5.
S0 has internal pull-down resistor, S1 has internal pull-up resistor.
Single ended tri-state output of the phase detector. A two pole
passive loop filter is connected to LF. See table on page 7 for proper
values.
Analog circuit ground.
Input control pin used to enable modulation at the Fout pin.
SSON = 0 = Modulation ON. (default)
SSON = 1 = Modulation OFF.
Has internal pull-down resistor.
Input control pins used to set the amount of modulation at Fout. See
table on page 6 for settings. S2 has internal pull-up resistor, S3 has
internal pull-down resistor.
Digital positive power supply. Should be kept separate from analog
power for best performance.
Modulated clock output.
Input pins control the input frequency range as described in table on
page 5.
R0 and R1 have internal pull-up resistor.
Digital Circuit Ground
Table 1.
3
4, 7
AVDD
S0, S1
Power
I
TTL
5
LF
O
Analog
6
8
AVSS
SSON
Ground
I
Ground
TTL
9, 11
S3, S2
I
TTL
10, 16
12
13, 14
DVDD
Fout
R1, R0
Power
O
I
Power
TTL
TTL
15
DVSS
Ground
Ground
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 3 of 14
+/+
YJGP VKOKPI KU ETKVKECN
SM532
Low EMI Sprectum Spread Clock
Approved Product
ABSOLUTE MAXIMUM RATINGS
This device contains circuitry to protect the inputs against damage due to high static voltages or electric fields;
however, precautions should be taken to avoid application of any voltage higher than the absolute maximum rated
voltages to this circuit. For proper operation, Vin and Vout should be constrained to the range, VSS < ( Vin or
Vout) < VDD. All digital inputs are tied high or low internally. Refers to electrical specifications for operating
supply range.
Item
Symbol
Min.
Max.
Units
Supply Voltage
VDD
0
6.0
VDC
Input, relative to VSS
VIRvss
-0.3
VDD +0.3
VDC
Output, relative to VSS
VORvss
-0.3
VDD +0.3
VDC
AVDD relative to DVDD
-100
+100
mv
∆Vpp
AVSS relative to DVSS
-100
+100
mv
∆Vss
0
Temperature, Operating
TOP
0
+ 70
C
0
Temperature, Storage
TST
- 65
+ 150
C
Table 2.
Electrical Characteristics
Characteristic
Symbol
Min.
Typ.
Max.
Units
Input Low Voltage
VIL
-
-
0.8
Vdc
Input High Voltage
VIH
2.0
-
-
Vdc
Input Low Current
IIL
-
-
100
µA
Input High Current
IIH
-
-
100
µA
Output Low Voltage IOL= 8mA, VDD = 5V
VOL
-
-
0.4
Vdc
Output High Voltage IOH = 8mA, VDD = 5V
VOH
VDD-1.0
-
-
Vdc
Output Low Voltage IOL= 5mA, VDD = 3.3V
VOL
-
-
0.4
Vdc
Output High Voltage IOH = 3mA,VDD = 3.3V
VOH
2.4
-
-
Vdc
Input Capacitance (Pin-1)
C
in1
-
3
-
pf
Output Capacitance (Pin-2)
C
in2
-
5
-
pf
Pull-Up Resistor values (pins 7, 11,13 and 14)
Rpu
100K
167K
300K
Ohms
Pull-Down resistor values (pins 4, 8 and 9)
Rpd
150K
250K
350K
Ohms
Tri-State Leakage Current (pins 5 and 12)
IOZ
-
5.0
-
µA
Static Supply Current (Power Down mode)
IDD
-
-
250
µA
5 Volt Dynamic Supply Current
ICC
-
25
30
ma
(Operating mode)
3 Volt Dynamic Supply Current
ICC
-
18
20
ma
(Operating mode)
Short Circuit Current (Fout)
ISC
-
-
30
ma
Test measurements performed at VDD = 3.3V +/-5% and 5V +/-10%, TA = 0°C to 70°C
Table 3.
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 4 of 14
+/+
YJGP VKOKPI KU ETKVKECN
SM532
Low EMI Sprectum Spread Clock
Symbol
tTLH
tTHL
tTLH
tTHL
tTLH
tTHL
tTLH
tTHL
TsymF1
Min
3.3
2.1
0.7
0.6
4.8
2.9
1.6
1.1
45
Typ
3.5
2.3
0.75
0.7
5.0
3.2
1.75
1.3
50
Max
3.8
2.5
0.8
0.8
5.4
3.4
1.9
1.5
55
Units
ns
ns
ns
ns
ns
ns
ns
ns
%
Approved Product
Timing Characteristics
Characteristic
Output Rise Time Measured at 10% - 90% @ 5 VDC
Output Fall Time Measured at 10% - 90% @ 5 VDC
Output Rise Time Measured at 0.8V - 2.0V @ 5 VDC
Output Fall Time Measured at 0.8V - 2.0 V @ 5 VDC
Output Rise Time Measured at 10% - 90% @ 3.3 VDC
Output Fall Time Measured at 10% - 90% @ 3.3 VDC
Output Rise Time Measured at 0.8V - 2.0V @ 3.3 VDC
Output Fall Time Measured at 0.8V - 2.0 V @ 3.3 VDC
Output Duty Cycle
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
30
30
30
60
60
60
60
60
60
120
120
120
Volts
Fout/
Fin
X
Note
1
2
4
0.5
1
2
+/- 10%
Fout (Range)
(MHz)
MIN
MAX
14
28
56
15
30
60
30
60
120
30
60
120
VDD = 3.3
Fin (Range)
(MHz)
MIN MAX
See
14
22.5
14
22.5
14
22.5
25
25
25
45
45
45
Volts
Fout/
Fin
X
Note
1
2
4
0.5
1
2
+/- 5%
Fout (Range)
(MHz)
MIN
MAX
14
28
56
12.5
25
50
12.5
25
50
22.5
45
90
22.5
45
90
22.5
45
90
Multiplier
Settings
S1
S0
0
0
0
1
1
0
1
1
0
1
1
1
0
1
Input Range
Settings
R1
R0
X
X
0
1
0
1
0
1
1
1
1
0
0
0
0.25
15
30
0
1
1
1
50
90
0.25
0.5
30
60
1
0
1
1
50
90
0.5
1
60
120
1
1
1
1
50
90
1
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
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