DATASHEET
ICS270
TRIPLE PLL FIELD PROGRAMMABLE VCXO CLOCK
Description
Features
The ICS270 field programmable VCXO clock synthesizer
generates up to eight high-quality, high-frequency clock
outputs including multiple reference clocks from a
low-frequency crystal input. It is designed to replace
crystals and crystal oscillators in most electronic systems.
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Using IDT’s VersaClockTM software to configure PLLs and
outputs, the ICS270 contains a One-Time Programmable
(OTP) ROM for field programmability. Programming
features include VCXO, eight selectable configuration
registers and up to two sets of four low-skew outputs.
Using Phase-Locked Loop (PLL) techniques, the device
runs from a standard fundamental mode, inexpensive
crystal, or clock. It can replace VCXOs, multiple crystals
and oscillators, saving board space and cost.
Packaged as 20-pin TSSOP
Eight addressable registers
Replaces multiple crystals and oscillators
Output frequencies up to 200 MHz at 3.3 V
Input crystal frequency of 5 to 27 MHz
Up to eight reference outputs
Up to two sets of four low-skew outputs
Operating voltages of 3.3 V
Controllable output drive levels
Advanced, low-power CMOS process
Available in Pb (lead) free packaging
NOTE: EOL for non-green parts to occur on
5/13/10 per PDN U-09-01
The ICS270 is also available in factory programmed custom
versions for high-volume applications.
Block Diagram
VDD
S2:S0
3
OTP
ROM
with
PLL
Values
3
CLK1
PLL1
CLK2
Divide
Logic
and
Output
Enable
Control
PLL2
VIN
CLK3
CLK4
CLK5
CLK6
PLL3
X1
Crystal
X2
CLK7
Voltage
Controlled
Crystal
Oscillator
External capacitors
are required.
CLK8
GND
2
PDTS
IDT™ / ICS™ TRIPLE PLL FIELD PROGRAMMABLE VCXO CLOCK
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Pin Assignment
VIN
1
20
S2
S0
2
19
VDD
S1
3
18
PDTS
VDD
CLK1
4
17
GND
5
16
CLK8
CLK2
6
15
CLK7
CLK3
7
14
CLK6
CLK4
GND
8
13
9
12
CLK5
VDD
10
11
X2
X1
20 pin (173 mil) TSSOP
Pin Descriptions
Pin
Number
Pin
Name
Pin
Type
1
VIN
Input
2
S0
Input
3
S1
Input
Pin Description
Voltage input to VCXO. Zero to 3.3V signal which controls the VCXO
frequency
Select pin 0. Internal pull-up resistor.
4
VDD
Power
Select pin 1. Internal pull-up resistor.
Connect to +3.3 V.
5
CLK1
Output
Output clock 1. Weak internal pull-down when tri-state.
6
CLK2
Output
Output clock 2. Weak internal pull-down when tri-state.
7
CLK3
Output
Output clock 3. Weak internal pull-down when tri-state.
8
CLK4
Output
Output clock 4. Weak internal pull-down when tri-state.
9
GND
Power
Connect to ground.
10
X1
XI
Crystal input. Connect this pin to a crystal.
11
X2
XO
12
VDD
Power
Crystal Output. Connect this pin to a crystal.
Connect to +3.3 V.
13
CLK5
Output
Output clock 5. Weak internal pull-down when tri-state.
14
CLK6
Output
Output clock 6. Weak internal pull-down when tri-state.
15
CLK7
Output
Output clock 7. Weak internal pull-down when tri-state.
16
CLK8
Output
Output clock 8. Weak internal pull-down when tri-state.
17
GND
Power
Connect to ground.
18
PDTS
Input
19
VDD
Power
Power-down tri-state. Powers down entire chip and tri-states clock outputs
when low. Internal pull-up resisitor.
Connect to +3.3 V.
20
S2
Input
Select pin 2. Internal pull-up resisitor.
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External Components
The external crystal must be connected as close to the chip
as possible and should be on the same side of the PCB as
the ICS270. There should be no via’s between the crystal
pins and the X1 and X2 device pins. There should be no
signal traces underneath or close to the crystal. See
application note MAN05.
The ICS270 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.
Crystal Tuning Load Capacitors
The crystal traces should include pads for small fixed
capacitors, one between X1 and ground, and another
between X2 and ground. Stuffing of these capacitors on the
PCB is optional. The need for these capacitors is
determined at system prototype evaluation, and is
influenced by the particular crystal used (manufacture and
frequency) and by PCB layout. The typical required
capacitor value is 1 to 4 pF.
Decoupling Capacitors
As with any high-performance mixed-signal IC, the ICS270
must be isolated from system power supply noise to perform
optimally.
To determine the need for and value of the crystal
adjustment capacitors, you will need a PC board of your final
layout, a frequency counter capable of about 1 ppm
resolution and accuracy, two power supplies, and some
samples of the crystals which you plan to use in production,
along with measured initial accuracy for each crystal at the
specified crystal load capacitance, CL.
Decoupling capacitors of 0.01µF must be connected
between each VDD and the PCB ground plane. For
optimum device performance, the decoupling capacitor
should be mounted on the component side of the PCB.
Aboid the use of vias on the decoupling circuit.
Quartz Crystal
The ICS270 VCXO function consists of the external crystal
and the integrated VCXO oscillator circuit. To assure the
best system performance (frequency pull range) and
reliability, a crystal device with the recommended
parameters (shown below) must be used, and the layout
guidelines discussed in the following section shown must be
followed.
To determine the value of the crystal capacitors:
1. Connect VDD of the ICS270 to 3.3 V. Connect pin 1 of the
ICS270 to the second power supply. Adjust the voltage on
pin 1 to 0V. Measure and record the frequency of the CLK
output.
2. Adjust the voltage on pin 1 to 3.3 V. Measure and record
the frequency of the same output.
The frequency of oscillation of a quartz crystal is determined
by its “cut” and by the load capacitors connected to it. The
ICS270 incorporates on-chip variable load capacitors that
“pull” (change) the frequency of the crystal. The crystal
specified for use with the ICS270 is designed to have zero
frequency error when the total of on-chip + stray
capacitance is 14 pF.
Recommended Crystal Parameters:
Initial Accuracy at 25° C
Temperature Stability
Aging
Load Capacitance
Shunt Capacitance, C0
C0/C1 Ratio
Equivalent Series Resistance
To calculate the centering error:
6 ( f3.0V – ft arg et ) + ( f0V – ft arg et )
Error = 10 x ----------------------------------------------------------------------- – errorxtal
ft arg et
±20 ppm
±30 ppm
±20 ppm
14 pf
7 pF Max
250 Max
35Ω Max
Where:
ftarget = nominal crystal frequency
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IDT VersaClock Software
errorxtal =actual initial accuracy (in ppm) of the crystal being
measured
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.
If the centering error is less than ±25 ppm, no adjustment is
needed. If the centering error is more than 25ppm negative,
the PC board has excessive stray capacitance and a new
PCB layout should be considered to reduce stray
capacitance. (Alternately, the crystal may be re-specified to
a higher load capacitance. Contact IDT for details.) If the
centering error is more than 25 ppm positive, add identical
fixed centering capacitors from each crystal pin to ground.
The value for each of these caps (in pF) is given by: External
Capacitor = 2 x (centering error)/(trim sensitivity)
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.
Trim sensitivity is a parameter which can be supplied by your
crystal vendor. If you do not know the value, assume it is 30
ppm/pF. After any changes, repeat the measurement to
verify that the remaining error is acceptably low (typically
less than ±25 ppm).
ICS270 Configuration Capabilities
The architecture of the ICS270 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 1024 and N = 1 to 32,895.
The ICS270 also provides separate output divide values,
from 2 through 63, 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
⋅
M
----N
Output Drive Control
The ICS270 has two output drive settings. Low drive should
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.)
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Absolute Maximum Ratings
Stresses above the ratings listed below can cause permanent damage to the ICS270. 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
Referenced to GND
Clock Outputs
Referenced to GND
Max.
Units
7
V
-0.5
VDD+0.5
V
-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 (ICS270PG/PGLF)
0
+70
°C
Ambient Operating Temperature (ICS270PGI/PGILF)
-40
+85
°C
Power Supply Voltage (measured in respect to GND)
+3.135
+3.465
V
4
ms
Power Supply Ramp Time
Reference crystal parameters
IDT™ / ICS™ TRIPLE PLL FIELD PROGRAMMABLE VCXO CLOCK
+3.3
Refer to page 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.
3.135
Max.
Units
3.465
V
Config. Dependent - See
VersaClockTM Estimates
mA
Operating Supply Current
Input High Voltage
IDD
Eight 33.3333 MHz outs,
PDTS = 1, no load, Note 1
27
mA
500
Input High Voltage
VIH
PDTS = 0, no load, Note 1
S2:S0
µA
V
Input Low Voltage
VIL
S2:S0
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
Output High Voltage
VOH
IOH = -8 mA (Low Drive);
IOH = -12 mA (High Drive)
Output Low Voltage
VOL
IOL = 8 mA (Low Drive);
IOL = 12 mA (High Drive)
Short Circuit Current
IOS
Low Drive
±40
High Drive
±70
mA
20
Ω
VDD/2+1
0.4
VDD-0.5
V
V
0.4
VDD/2+1
V
V
VDD/2-1
V
VDD-0.4
V
2.4
V
0.4
V
Nom. Output Impedance
ZO
Internal Pull-up Resistor
RPUS
S2:S0, PDTS
190
kΩ
Internal Pull-down Resistor
RPD
CLK outputs
220
kΩ
Input Capacitance
CIN
Inputs
4
pF
Note 1: Example with 25 MHz crystal input with eight outputs of 33.3 MHz, no load, and VDD = 3.3 V.
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AC Electrical Characteristics
Unless stated otherwise, VDD = 3.3V ±5%, Ambient Temperature -40 to +85° C
Parameter
Input Frequency
Symbol
FIN
Conditions
Fundamental crystal
Output Frequency
Crystal Pullability
FP
0V< VIN < 3.3 V, Note 1
VCXO Gain
Min.
Typ.
Max. Units
5
27
MHz
0.314
200
MHz
100
ppm
VIN = VDD/2 + 1 V,
Note 1
110
ppm/V
Output Rise/Fall Time
tOF
80% to 20%, high drive,
Note 2
1.0
ns
Output Rise/Fall Time
tOF
80% to 20%, low drive,
Note 2
2.0
ns
Duty Cycle
Note 3
Power-up time
PLL lock-time from
power-up
One Sigma Clock Period Jitter
Maximum Absolute Jitter
tja
Pin-to-Pin Skew
40
49-51
60
%
4
10
ms
PDTS goes high until
stable CLK output
0.6
2
ms
Configuration Dependent
50
ps
Deviation from Mean,
Configuration Dependent
+200
ps
Low Skew Outputs
-250
250
ps
Note 1: External crystal device must conform with Pullable Crystal Specifications listed on page 3.
Note 2: Measured with 15 pF load.
Note 3: Duty Cycle is configuration dependent. Most configurations are min 45% / max 55%.
Thermal Characteristics
Parameter
Symbol
Conditions
Min.
Typ.
Max. Units
Thermal Resistance Junction to
Ambient
θ JA
Still air
93
° C/W
θ JA
1 m/s air flow
78
° C/W
θ JA
3 m/s air flow
65
° C/W
Thermal Resistance Junction to Case
θ JC
20
° C/W
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Marking Diagram
Marking Diagram (Pb free)
20
11
20
270PG
######
YYWW
11
270PGL
######
YYWW
1
10
1
10
20
11
20
11
270PGI
######
YYWW
1
270PGIL
######
YYWW
10
1
10
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 temp. range (if applicable).
4. “L” denotes Pb (lead) free package.
5. Bottom marking: country of origin.
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Package Outline and Package Dimensions (20-pin TSSOP, 173 Mil. Body)
Package dimensions are kept current with JEDEC Publication No. 95
24
Millimeters
Symbol
E1
INDEX
AREA
A
A1
A2
b
C
D
E
E1
e
L
α
E
1 2
D
Min
Inches
Max
Min
—
1.20
0.05
0.15
0.80
1.05
0.19
0.30
0.09
0.20
6.40
6.60
6.40 BASIC
4.30
4.50
0.65 Basic
0.45
0.75
0°
8°
Max
—
.047
0.002
0.006
0.032
0.041
0.007
0.012
0.0035 0.008
0.252
0.260
0.252 BASIC
0.169
0.177
0.0256 Basic
.018
.030
0°
8°
A
A2
A1
c
- Ce
b
SEATING
PLANE
.10 (.004)
IDT™ / ICS™ TRIPLE PLL FIELD PROGRAMMABLE VCXO CLOCK
C
9
L
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Ordering Information
Part / Order Number
Marking
Shipping Packaging
Tubes
20-pin TSSOP
0 to +70° C
See page 8 above
Tubes
20-pin TSSOP
-40 to +85° C
270PGLF
Tubes
20-pin TSSOP
0 to +70° C
270PGILF
Tubes
20-pin TSSOP
-40 to +85° C
270PG*
270PGI*
Package
Temperature
270G-XX*
270G-XX
Tubes
20-pin TSSOP
0 to +70° C
270GI-XX*
270GI-XX
Tubes
20-pin TSSOP
-40 to +85° C
270G-XXLF
270GXXL
Tubes
20-pin TSSOP
0 to +70° C
270GI-XXLF
270GIXXL
Tubes
20-pin TSSOP
-40 to +85° C
270G-XXT*
270G-XX
Tape and Reel
20-pin TSSOP
0 to +70° C
270GI-XXT*
270GIXX
Tape and Reel
20-pin TSSOP
-40 to +85° C
270G-XXLFT
270GXXL
Tape and Reel
20-pin TSSOP
0 to +70° C
270GI-XXLFT
270GIXXL
Tape and Reel
20-pin TSSOP
-40 to +85° C
*NOTE: EOL for non-green parts to occur on 5/13/10 per PDN U-09-01
Parts that are ordered with a “LF” suffix to the part number are the Pb-Free configuration and are RoHS compliant.
The ICS270G-XX, ICS270G-XXLF, ICS270GI-XX, and ICS270GI-XXLF are factory programmed versions of the ICS270PG,
ICS270PGLF, ICS270PGI, and ICS270PGLF. 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.
VersaClockTM is a trademark of Integrated Device Technology, Inc. All rights reserved.
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Innovate with IDT and accelerate your future networks. Contact:
www.IDT.com
For Sales
For Tech Support
800-345-7015
408-284-8200
Fax: 408-284-2775
www.idt.com/go/clockhelp
Corporate Headquarters
Integrated Device Technology, Inc.
www.idt.com
© 2006 Integrated Device Technology, Inc. All rights reserved. Product specifications subject to change without notice. IDT and the IDT logo are trademarks of Integrated Device
Technology, Inc. Accelerated Thinking is a service mark of Integrated Device Technology, Inc. All other brands, product names and marks are or may be trademarks or registered
trademarks used to identify products or services of their respective owners.
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