SG521/22/24/28
Spread Spectrum Clock Generator
Approved Product
Features
•
•
•
•
•
•
•
•
•
•
•
•
•
Generates Spread Spectrum Clock (SSC)
Programmable Frequencies from 10 to 120 MHz
1.00% and 3.00% 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
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
th
the higher the frequency the greater the energy reduction. The 5 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 1.00% or 3.00% 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. 1.3
7/21/1999
Page 1 of 12
SG521/22/24/28
Spread Spectrum Clock Generator
Approved Product
Block Diagram
= Control
VCO / N
LF
VCO
2
3
OSCin
OSCout
/R
Phase
Detector
Fixed Frequency
PLL
MPCLK/S3
14
7
8
5
9
10
16
S0
S1
S4
SSON
SS-SEL
TEST
SSCG/
Power Down
Control
Power On/Reset
VDD VDD VDD
VSS
VSS
VSS
Output
Divider
PRCLK/S2
12
1
6
15
4
11
13
Figure 1. Block Diagram
Ordering Information
Part Number
IMISG521BXB
IMISG522BXB
IMISG524BXB
IMISG528BXB
Number of Pins and Package
16-Pin SOIC
16-Pin SOIC
16-Pin SOIC
16-Pin SOIC
Temperature Range
0 to 70°C
0 to 70°C
0 to 70°C
0 to 70°C
INTERNATIONAL MICROCIRCUITS,INC. 525 LOS COCHES ST.,
MILPITAS, CA 95035 408-263-6300, FAX 408-263-6571
http:/www.imicorp.com
Rev. 1.3
7/21/1999
Page 2 of 12
SG521/22/24/28
Spread Spectrum Clock Generator
Approved Product
Pin Configuration
VDD
OSCin
OSCout
VSS
S4
VDD
S0
S1
1
2
3
4
5
6
7
8
SG521
----------
SG522
----------
SG524
----------
SG528
16
15
14
13
12
11
10
9
TEST
VDD
MPCLK/S3
VSS
PRCLK/S2
VSS
SS-SEL
SSON
Figure 2. SG521/22/24/28 SOIC Package Pin Assignment
Pin Description
Pin
#
1
2
3
4
5
Signal
Name
VDD
OSCin
OSCout
VSS
S4
I/O
P
I
O
P
I
Default
State
Power
N/A
N/A
GND.
1
Positive Power Supply.
Input pin of on-chip reference oscillator.
Description
Output pin of on-chip reference oscillator. If Crystal Oscillator is used, this pin is left unconnected.
Power Supply Ground.
Digital logic input used to select required crystal input frequency range, frequency spread clock
(PRCLK) and non-spread clock MPCLK output frequencies. This pin has internal 150 K ohm pull-up
resistor to VDD. Refer to Frequency Selection Tables for Truth Table.
Positive Power Supply
Digital logic input used to select required crystal input frequency range, frequency spread clock
(PRCLK) and non-spread clock MPCLK output frequencies. This pin has internal 150 K ohm pull-down
resistor to GND. Refer to Frequency Selection Tables for Truth Table.
Digital logic input used to select required crystal input frequency range, frequency spread clock
(PRCLK) and non-spread clock MPCLK output frequencies. This pin has internal 150 K ohm pull-down
resistor to GND. Refer to Frequency Selection Tables for Truth Table.
Input digital control pin used to enable or disable the frequency modulation function at PRCLK Output
(Pin-12). When this pin is low (GND) spread function is on. When high (VDD), spread function is turned-
off. This pin has 150 K ohm internal pulled-up to VDD.
Used to select total Frequency Modulation (Spread) amount. The spread is either 1.00%(Narrow) or
3.00%(Wide). Both spreads are down-center with respect to output frequency at PRCLK (Pin-12). Refer
to Frequency and Spread selection Tables for the Spread selection logic states. This pin has 150 K
internal pull-up resistor to VDD.
Power Supply Ground
Bi-directional pin used to share input control and output drive function. During power-on, this pin is a
digital input and latches that state (High or Low) into an internal register as a valid S2 state. After power
has reached a pre-determined level, pin 12 becomes the driver for the PRCLK modulated output clock.
This pin has 150 K ohm internal pull-up resistor to VDD. For proper operation, an external 4.7 K ohm
resistor connected to VDD or VSS is required. Refer to Frequency Selection Truth Tables for proper
operation.
Power Supply Ground
Bi-directional pin used to share input control and output drive function. During power-on, this pin is a
digital input and latches that state (High or Low) into an internal register as a valid S3 state. After power
has reached a pre-determined level, pin 14 becomes the driver for the MPCLK non-modulated output
clock. This pin has 150 K ohm internal pull-up resistor to VDD. Refer to Frequency Selection Truth
Tables for proper operation.
Positive Power Supply
Provides Power-Down and Hi-Z function when used in conjunction with S0 and S1 digital inputs. This
pin has internal pull-down to GND. Refer to Frequency Selection Truth Tables for proper operation.
6
7
VDD
S0
P
I
0
8
S1
I
0
9
SSON
I
1
10
SS-SEL
I
1
11
12
VSS
PRCLK/S2
P
I/O
GND.
1
13
14
VSS
MPCLK/S3
P
O/I
GND.
1
15
16
VDD
TEST
P
I
Power
0
INTERNATIONAL MICROCIRCUITS,INC. 525 LOS COCHES ST.,
MILPITAS, CA 95035 408-263-6300, FAX 408-263-6571
http:/www.imicorp.com
Rev. 1.3
7/21/1999
Page 3 of 12
SG521/22/24/28
Spread Spectrum Clock Generator
Approved Product
Absolute Maximum Ratings
Symbol
VDD
Vimax
Vomax
Top
Tst
Tjc
Parameter
Supply Voltage
Input Voltage Relative to VSS
Output Voltage Relative to VSS
Operating Temperature
Storage Temperature
Soldering Junction Temperature
Min.
VSS
-0.3
-0.3
0
-55
-
Typical
3.3/5.0
-
-
-
-
-
Max.
7.0
VDD+0.3
VDD+0.3
70
150
300
Unit
V
V
V
°C
°C
°C
Conditions
Measured from pin 1, 6 or 15 to VSS
Pins 5, 7, 8, 9, 10, 12, 14 and 16.
Pins 12 and 14
Refer to QA report.
Refer to QA report.
10 seconds soldering
Note: Operation at any Absolute Maximum Rating is not implied. Refer to DC Electrical Characteristics for
proper Operating Range.
Test Conditions: VDD=5.0V (+/-10%), CL=15pF, Operating Temperature = 0 to 70°C unless otherwise
specified
DC Electrical Characteristics
Symbol
VDD
OSCin-cl
Vinl
Vinh
Iinl
Iinh
Rpu/Rpd
Zo
Zo
Cin
IDDt
IDDs
IDDd
IDDpd
Isco
Parameter
Power Supply Voltage, Operating
Oscillator Input Load Capacitance
Input Voltage, Low
Input Voltage, High
Input Current, Low
Input Current, High
Pull-up/down Resistors
Clock Output Impedance, PRCLK
Clock Output Impedance, MPCLK
Capacitance, Input
Current, Leakage, Tri-State
Current, Power Supply, Static
Current, Power Supply, Dynamic
Current, Power Supply, Power Down
Current, Output, Short Circuit
-
-
-
-
25
-
2.0
-
-
100
-
-
Min.
3.135
Typical
3.3/5.0
3
5
-
-
-
-
150
12.5
23.0
3
-
200
-
-
30
5
500
80
25
-
0.8
-
50
50
250
-
-
Max.
5.5
Unit
V
pF
pF
V
V
µA
µA
KΩ
Ohms
Ohms
pF
µA
µA
mA
µA
mA
Conditions
Measured from pin 1, 6 or 15 to VSS
Pin 2.
Pin 3.
Pins 5, 7, 8, 9, 10, 12, 14 and 16.
Pins 5, 7, 8, 9, 10, 12, 14 and 16.
Pins 5, 7, 8, 9, 10, 12, 14 and 16.
Pins 5, 7, 8, 9, 10, 12, 14 and 16.
Pins 5, 7, 8, 9, 10, 12, 14 and 16.
VDD = 5.00 VDC
VDD = 5.00 VDC
Pins 2, 5, 7, 8, 9, 10, 12, 14 and 16
Pins 2, 5, 7, 8, 9, 10, 12, 14 and 16
Pins 2, 5, 7, 8, 9, 10, 12, 14 and 16
Ref. = 48 MHz,
PRCLK = 50.00 MHz, No Load.
Test = 1.
PRCLK and MPCLK
OSCout-cl Oscillator Output Load Capacitance
Notes: Pins 5, 7, 8, 9, 10, 12, 14 and 16 have internal pull-up or pull-down resistors. These resistors define a
default operating state for this part. Pins 12 and 14 require an external resistor for proper operation.
INTERNATIONAL MICROCIRCUITS,INC. 525 LOS COCHES ST.,
MILPITAS, CA 95035 408-263-6300, FAX 408-263-6571
http:/www.imicorp.com
Rev. 1.3
7/21/1999
Page 4 of 12
SG521/22/24/28
Spread Spectrum Clock Generator
Approved Product
Test Conditions: VDD=5.0V (+/-10%) , CL=15pF and TA=0 to 70°C unless otherwise specified
Timing Electrical Characteristics
Symbol
Find
Fout
Tr
Tf
Tr
Tf
PRdty
MPdty
PRccj
MPccj
PRccj
MPccj
Notes:
** Modulation is turned off for these measurements.
Characteristic
Reference Frequency, delta
Frequency, Output
Rise Time, PRCLK,
Fall Time, PRCLK
Rise Time, MPCLK
Fall Time, MPCLK
Duty Cycle, PRCLK
Duty Cycle, MPCLK
Jitter, Cycle to Cycle, PRCLK
Jitter, Cycle to Cycle, MPCLK
Jitter, Cycle to Cycle, PRCLK
Jitter, Cycle to Cycle, MPCLK
Min.
TBD
10
250
200
450
300
45
45
100
100
100
100
Typ.
-
-
-
-
-
50
50
-
-
-
-
Max.
TBD
120
500
300
650
400
55
55
250
250
250
250
Unit
%
MHz
ps
ps
ps
ps
%
%
ps
ps
ps
ps
Conditions
OSCin = 14.318, 44.24 and 48 MHz
PRCLK
Measured at 0.4 – 2.4V, @50.00 MHz
Measured at 0.4 – 2.4V, @50.00 MHz
Measured at 0.4 – 2.4V, @50.00 MHz
Measured at 0.4 – 2.4V, @50.00 MHz
Measured at 1.5 Volts
Measured at 1.5 Volts
Spread Off @ 50.0 MHz
Spread Off
Spread On @ 50.0 MHz
Spread On.
Crystal Selection Truth Table
The SG521, 2, 4 and 8 uses one of three different reference frequencies. Determine the desired PRCLK frequency
from the frequency selection tables in table 5 – 8. Determine the REQUIRED REFERENCE FREQUENCY,
MPCLK and Product from table 1 and set S2, S3 and S4 control lines as indicated. Note that MPCLK/S3 and
PRCLK/S2 are bi-directional signals and serve as an input control line during power up and an output after power is
stable.
PRODUCT
SG528
SG521/22/24
SG521/22/24/28
SG521/22/24/28
SG521/22/24/28
SG528
SG521/22/24
SG521/22/24/28
SG521/22/24/28
SG521/22/24/28
REQUIRED
REF. Input
(MHz)
44.240
48.000
14.318
48.000
44.240
44.240
14.318
14.318
48.000
44.240
MPCLK OUT
(MHz)
(Pin 14)
3.7 (44.24/12)
48.000
48.000
48.000
3.7 (44.24/12)
11.6 (44.24/4)
48.000
48.000
48.000
11.6 (44.24/4)
Table. 1
S4
(Pin 5)
0
0
0
0
0
1
1
1
1
1
MPCLK/S3
(Pin 14)
0
0
0
1
1
0
0
0
1
1
PRCLK/S2
(Pin 12)
0
0
1
0
1
0
0
1
0
1
INTERNATIONAL MICROCIRCUITS,INC. 525 LOS COCHES ST.,
MILPITAS, CA 95035 408-263-6300, FAX 408-263-6571
http:/www.imicorp.com
Rev. 1.3
7/21/1999
Page 5 of 12
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