IDT ICS252M-XXT Field programmable dual output ss versaclock synthesizer Datasheet

DATASHEET
FIELD PROGRAMMABLE DUAL OUTPUT SS VERSACLOCK SYNTHESIZER
Description
Features
The ICS252 is a low cost, dual-output, field programmable
clock synthesizer. The ICS252 can generate two output
frequencies from 314 kHz to 200 MHz using up to two
independently configurable PLLs. The outputs may employ
Spread Spectrum techniques to reduce system
electro-magnetic interference (EMI).
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Using IDT’s VersaClock software to configure the PLL and
output, the ICS252 contains a One-Time Programmable
(OTP) ROM to allow field programmability. Programming
features include 4 selectable configuration registers.
The device employs Phase-Locked Loop (PLL) techniques
to run from a standard fundamental mode, inexpensive
crystal, or clock. It can replace multiple crystals and
oscillators, saving board space and cost.
ICS252
8-pin SOIC package
Two addressable registers
Input crystal frequency of 5 to 27 MHz
Clock input frequency of 3 to 150 MHz
Output clock frequencies up to 200 MHz
Configurable Spread Spectrum Modulation
Operating voltage of 3.3 V
Replaces multiple crystals and oscillators
Controllable output drive levels
Advanced, low-power CMOS process
Available in RoHS 5 (green) or RoHS 6 (green and lead
free) compliant package
The device also has a power-down feature that tri-states the
clock outputs and turns off the PLLs when the PDTS pin is
taken low.
The ICS252 is also available in factory programmed custom
versions for high-volume applications.
Block Diagram
VDD
SEL
OTP
ROM
with
PLL
Values
PLL1
Divide
Logic
and
Output
Enable
Control
PLL2
X1
CLK1
CLK2
Crystal
Oscillator
Crystal
X2
External capacitors
are required.
GND
PDTS
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Pin Assignment
EPROM CLOCK SYNTHESIZER
Output Clock Selection Table
SEL
1
8
PDTS
VDD
2
7
GND
X1/ICLK
3
6
CLK2
X2
4
5
CLK1
SEL
CLK1 (MHz)
CLK2 (MHz)
Spread
Percentage
0
User
Configurable
User
Configurable
User
Configurable
User
Configurable
User
Configurable
User
Configurable
1
8-pin (150 mil) SOIC
Pin Descriptions
Pin
Number
Pin
Name
Pin
Type
Pin Description
1
SEL
Input
Select pin for frequency selection on CLK1 and CLK2. Internal pull-up resistor.
2
VDD
Power
3
X1/ICLK
XI
Connect to +3.3 V.
Connect this pin to a crystal or external clock input.
4
X2
XO
5
CLK1
Output
Clock1 output. Weak internal pull-down, low when power down.
Connect this pin to a crystal, or float for clock input.
6
CLK2
Output
Clock2 output. Weak internal pull-down, low when power down.
7
GND
Power
8
PDTS
Input
Connect this to ground.
Powers down entire chip. Tri-states CLK outputs when low. No internal pull-up
resistor. The pin must be tied either directly or through the external resistor to
VDD ro GND. External resistor value must be less than 15kOhm.
External Components
The ICS252 requires a minimum number of external
components for proper operation.
Series Termination Resistor
Clock output traces over one inch should use series
termination. To series terminate a 50Ω trace (a commonly
used trace impedance), place a 33Ω resistor in series with
the clock line, as close to the clock output pin as possible.
The nominal impedance of the clock output is 20Ω.
Decoupling Capacitor
As with any high-performance mixed-signal IC, the ICS252
must be isolated from system power supply noise to perform
optimally.
A decoupling capacitor of 0.01µF must be connected
between VDD and the PCB ground plane.
Crystal Load Capacitors
The device crystal connections should include pads for
small capacitors from X1 to ground and from X2 to ground.
These capacitors are used to adjust the stray capacitance
of the board to match the nominally required crystal load
capacitance. Because load capacitance can only be
increased in this trimming process, it is important to keep
stray capacitance to a minimum by using very short PCB
traces (and no vias) been the crystal and device. Crystal
capacitors must be connected from each of the pins X1 and
X2 to ground.
The value (in pF) of these crystal caps should equal (CL -6
pF)*2. In this equation, CL= crystal load capacitance in pF.
Example: For a crystal with a 16 pF load capacitance, each
crystal capacitor would be 20 pF [(16-6) x 2 = 20].
PCB Layout Recommendations
For optimum device performance and lowest output phase
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noise, the following guidelines should be observed.
1) The 0.01µF decoupling capacitor should be mounted on
the component side of the board as close to the VDD pin as
possible. No vias should be used between the decoupling
capacitor and VDD pin. The PCB trace to VDD pin should
be kept as short as possible, as should the PCB trace to the
ground via. Distance of the ferrite bead and bulk decoupling
from the device is less critical.
2) The external crystal should be mounted just next to the
device with short traces. The X1 and X2 traces should not
be routed next to each other with minimum spaces, instead
they should be separated and away from other traces.
3) To minimize EMI, the 33Ω series termination resistor (if
needed) should be placed close to the clock output.
4) An optimum layout is one with all components on the
same side of the board, minimizing vias through other signal
layers. Other signal traces should be routed away from the
ICS252. This includes signal traces just underneath the
device, or on layers adjacent to the ground plane layer used
by the device.
ICS252 Configuration Capabilities
The architecture of the ICS252 allows the user to easily
configure the device to a wide range of output frequencies,
for a given input reference frequency.
The frequency multiplier PLL provides a high degree of
precision. The M/N values (the multiplier/divide values
available to generate the target VCO frequency) can be set
within the range of M = 1 to 2048 and N = 1 to 1024.
The ICS252 also provides separate output divide values,
from 2 through 20, to allow the two output clock banks to
support widely differing frequency values from the same
PLL.
Each output frequency can be represented
as:
OutputFreq
=
REFFreq
-------------------------------------OutputDivide
⋅
M
----N
Output Drive Control
The ICS252 has two output drive settings. Low drive should
EPROM CLOCK SYNTHESIZER
be selected when outputs are less than 100 MHz. High drive
should be selected when outputs are greater than 100 MHz.
(Consult the AC Electrical Characteristics for output rise and
fall times for each drive option.)
IDT VersaClock Software
IDT applies years of PLL optimization experience into a user
friendly software that accepts the user’s target reference
clock and output frequencies and generates the lowest jitter,
lowest power configuration, with only a press of a button.
The user does not need to have prior PLL experience or
determine the optimal VCO frequency to support multiple
output frequencies.
VersaClock software quickly evaluates accessible VCO
frequencies with available output divide values and provides
an easy to understand, bar code rating for the target output
frequencies. The user may evaluate output accuracy,
performance trade-off scenarios in seconds.
Spread Spectrum Modulation
The ICS252 utilizes frequency modulation (FM) to distribute
energy over a range of frequencies. By modulating the
output clock frequencies, the device effectively lowers
energy across a broader range of frequencies; thus,
lowering a system’s electro-magnetic interference (EMI).
The modulation rate is the time from transitioning from a
minimum frequency to a maximum frequency and then back
to the minimum.
Spread Spectrum Modulation can be applied as either
“center spread” or “down spread”. During center spread
modulation, the deviation from the target frequency is equal
in the positive and negative directions. The effective
average frequency is equal to the target frequency. In
applications where the clock is driving a component with a
maximum frequency rating, down spread should be applied.
In this case, the maximum frequency, including modulation,
is the target frequency. The effective average frequency is
less than the target frequency.
The ICS252 operates in both center spread and down
spread modes. For center spread, the frequency can be
modulated between +/- 0.125% to +/-2.0%. For down
spread, the frequency can be modulated between -0.25% to
-4.0%.
Both output frequency banks will utilize identical spread
spectrum percentage deviations and modulation rates, if a
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common VCO frequency can be identified.
Spread Spectrum Modulation Rate
The spread spectrum modulation frequency applied to the
output clock frequency may occur at a variety of rates. For
applications requiring the driving of “down-circuit” PLLs,
EPROM CLOCK SYNTHESIZER
Zero Delay Buffers, or those adhering to PCI standards, the
spread spectrum modulation rate should be set to 30-33
kHz. For other applications, a 120 kHz modulation option is
available.
Absolute Maximum Ratings
Stresses above the ratings listed below can cause permanent damage to the ICS252. These ratings, which are
standard values for IDT commercially rated parts, are stress ratings only. Functional operation of the device at
these or any other conditions above those indicated in the operational sections of the specifications is not implied.
Exposure to absolute maximum rating conditions for extended periods can affect product reliability. Electrical
parameters are guaranteed only over the recommended operating temperature range.
Parameter
Condition
Min.
Supply Voltage, VDD
Referenced to GND
Inputs
Clock Outputs
Max.
Units
-0.5
7
V
Referenced to GND
-0.5
VDD+ 0.5
V
Referenced to GND
-0.5
VDD+ 0.5
V
-65
150
°C
260
°C
125
°C
Storage Temperature
Soldering Temperature
Typ.
Max 10 seconds
Junction Temperature
Recommended Operation Conditions
Parameter
Min.
Typ.
Max.
Units
Ambient Operating Temperature (ICS252M)
0
+70
°C
Ambient Operating Temperature (ICS252MI)
-40
+85
°C
+3.465
V
4
ms
Power Supply Voltage (measured in respect to GND)
+3.135
Power Supply Ramp Time
IDT™ / ICS™ FIELD PROGRAMMABLE DUAL OUTPUT SS VERSACLOCK SYNTHESIZER 4
+3.3
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DC Electrical Characteristics
Unless stated otherwise, VDD = 3.3 V ±5%, Ambient Temperature -40 to +85° C
Parameter
Operating Voltage
Symbol
Conditions
VDD
Min.
Typ.
Max.
Units
3.135
3.3
3.465
V
Configuration Dependent
- See VersaClockTM
Operating Supply Current
Input High Voltage
IDD
mA
Two 33.3333 MHz output,
PDTS = 1, no load
Note 1
16
mA
500
µA
V
Input High Voltage
VIH
PDTS = 0
SEL
Input Low Voltage
VIL
SEL
Input High Voltage, PDTS
VIH
Input Low Voltage, PDTS
VIL
Input High Voltage
VIH
ICLK
Input Low Voltage
VIL
ICLK
Output High Voltage
(CMOS High)
VOH
IOH = -4 mA
VDD-0.4
V
Output High Voltage
VOH
IOH = -8 mA (Low Drive);
IOH = -12 mA (High Drive)
2.4
VDD-0.4
V
Output Low Voltage
VOL
IOL = 8 mA (Low Drive);
IOL = 12 mA (High Drive)
Short Circuit Current
IOS
±70
mA
Nominal Output
Impedance
ZO
20
Ω
VDD/2+1
0.4
VDD-0.5
V
V
0.4
VDD/2+1
V
V
VDD/2-1
0.4
V
V
Internal Pull-up Resistor
RPUP
SEL
120
kΩ
Internal Pull-down
Resistor
RPD
Clock outputs CLK1 and
CLK2
120
kΩ
Input Capacitance
CIN
inputs
4
pF
Note 1: Example with 25 MHz crystal input with output of 33.3 MHz, no load, and VDD = 3.3 V.
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AC Electrical Characteristics
Unless stated otherwise, VDD = 3.3 V ±5%, Ambient Temperature -40 to +85° C
Parameter
Input Frequency
Symbol
FIN
Conditions
Min.
Typ.
Max. Units
Fundamental Crystal
5
27
MHz
Input Clock
2
150
MHz
0.314
200
MHz
Output Frequency
Output Rise Time
tOR
20% to 80%, Note 1
1
ns
Output Fall Time
tOF
80% to 20%, Note 1
1
ns
Duty Cycle
Note 2
Power-up Time
One Sigma Clock Period Jitter
Maximum Absolute Jitter
tja
40
49-51
60
%
PLL lock time from
power-up
4
10
ms
PDTS goes high until
stable CLK output,
Spread Spectrum Off
.6
2
ms
PDTS goes high until
stable CLK output,
Spread Spectrum On
4
7
ms
Configuration Dependent
50
ps
Deviation from Mean.
Configuration Dependent
+200
ps
Note 1: Measured with 15 pF load.
Note 2: Duty Cycle is configuration dependent. Most configurations are minimum 45% and maximum 55%.
Thermal Characteristics
Parameter
Thermal Resistance Junction to
Ambient
Thermal Resistance Junction to Case
Symbol
Conditions
Min.
Typ.
Max. Units
θJA
Still air
150
° C/W
θJA
1 m/s air flow
140
° C/W
θJA
3 m/s air flow
120
° C/W
40
° C/W
θJC
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Marking Diagram
EPROM CLOCK SYNTHESIZER
Marking Diagram (Pb free)
8
5
8
252PML
######
YYWW
252PM
######
YYWW
1
4
8
5
1
4
4
8
5
252PMIL
######
YYWW
252PMI
######
YYWW
1
5
1
4
Notes:
1. ###### is the lot number.
2. YYWW is the last two digits of the year and week that the part was assembled.
3. “I” denotes industrial temperature range (if applicable).
4. “L” denotes RoHS compliant package.
5. Bottom marking: country of origin.
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EPROM CLOCK SYNTHESIZER
Package Outline and Package Dimensions (8-pin SOIC, 150 Mil. Body)
Package dimensions are kept current with JEDEC Publication No. 95
Millimeters
8
Symbol
E
Min
A
A1
B
C
D
E
e
H
h
L
α
H
INDEX
AREA
1 2
D
A
Inches
Max
Min
1.35
1.75
0.10
0.25
0.33
0.51
0.19
0.25
4.80
5.00
3.80
4.00
1.27 BASIC
5.80
6.20
0.25
0.50
0.40
1.27
0°
8°
Max
.0532
.0688
.0040
.0098
.013
.020
.0075
.0098
.1890
.1968
.1497
.1574
0.050 BASIC
.2284
.2440
.010
.020
.016
.050
0°
8°
h x 45
A1
C
-Ce
B
SEATING
PLANE
L
.10 (.004)
C
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EPROM CLOCK SYNTHESIZER
Ordering Information
Part / Order Number
ICS252PM
ICS252PMI
ICS252PMLF
ICS252PMILF
ICS252M-XX
ICS252MI-XX
ICS252M-XXLF
ICS252MI-XXLF
ICS252M-XXT
ICS252MI-XXT
ICS252M-XXLFT
ICS252MI-XXLFT
Marking
See Page 7 Above
252M-XX
252MIXX
252MXXL
252MIXXL
252M-XX
252MIXX
252MXXL
252MIXXL
Shipping Packaging
Package
Temperature
Tubes
Tubes
Tubes
Tubes
Tubes
Tubes
Tubes
Tubes
Tape and Reel
Tape and Reel
Tape and Reel
Tape and Reel
8-pin SOIC
8-pin SOIC
8-pin SOIC
8-pin SOIC
8-pin SOIC
8-pin SOIC
8-pin SOIC
8-pin SOIC
8-pin SOIC
8-pin SOIC
8-pin SOIC
8-pin SOIC
0 to +70° C
-40 to +85° C
0 to +70° C
-40 to +85° C
0 to +70° C
-40 to +85° C
0 to +70° C
-40 to +85° C
0 to +70° C
-40 to +85° C
0 to +70° C
-40 to +85° C
Parts that are ordered with a “LF” suffix to the part number are the Pb-Free configuration and are RoHS compliant.
The ICS252M-XX, ICS252M-XXLF, ICS252MI-XX, and ICS252MI-XXLF are factory programmed versions of the ICS252PM,
ICS252PMLF, ICS252PMI, and ICS252PMILF. A unique “-XX” suffix is assigned by the factory for each custom configuration, and
a separate data sheet is kept on file. For more information on custom part numbers programmed at the factory, please contact
your local IDT sales and marketing representative.
While the information presented herein has been checked for both accuracy and reliability, IDT assumes no responsibility for either its use
or for the infringement of any patents or other rights of third parties, which would result from its use. No other circuits, patents, or licenses
are implied. This product is intended for use in normal commercial applications. Any other applications such as those requiring extended
temperature range, high reliability, or other extraordinary environmental requirements are not recommended without additional processing
by IDT. IDT reserves the right to change any circuitry or specifications without notice. IDT does not authorize or warrant any IDT product
for use in life support devices or critical medical instruments.
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EPROM CLOCK SYNTHESIZER
Revision History
Rev.
Originator
Date
Description of Change
A
R.Willner
04/08/05
Preliminary release.
B
R.Willner
01/16/06
Corrected Block Diagram. Released from Prelim to Final.
C
R.Willner
06/13/06
Added "-XX" part ordering information and specific note pertaining to custom
configurations of device.
D
08/10/07
Removed “Inernal pull-up resistor” info from PDTS pin description and added extrenal
pull-up resistor statement/information.
E
08/20/07
Changed S1 pin name to “SEL”; removed references to PDTS pin; changed pull-up
resistor value from 190 to 120 kOhms.
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EPROM CLOCK SYNTHESIZER
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For Sales
For Tech Support
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