DATASHEET
PC PERIPHERAL CLOCK
Description
The ICS409 is a cost-effective clock synthesizer
developed to optimize component count for PC
peripheral applications. The device supports a
common, low cost 14.31818 MHz crystal using an
on-chip crystal oscillator. The device locks all output
frequencies to enhance system performance. By
supporting common PC peripheral interface
frequencies including dual 25 MHz and 40/80 MHz
frequencies the clock lowers chip count enhancing
system cost and reliability.
The ICS409 utilizes a low pin count 8-pin SOIC
package to optimize board space.
IDT is a leader in low jitter and power consumer
application clock sources. These devices are capable
of supporting CCD, video, audio, USB, CPU, and other
peripherals.
ICS409
Features
•
•
•
•
•
•
•
•
Pin compatible with FS6286-01
Low operating voltage of 3.3V
On-chip oscillator supports 14.31818 MHz crystal
Fixed dual 25 MHz clocks for Ethernet
40/80 MHz selected on rising edge of OE/LAT pin
Power consumption of 15 mA (typ)
Duty cycle of 45 to 55%
Packaged in 8-pin SOIC (Pb-free)
Block Diagram
VDD
25M
X1
14.31818 MHz
Fundamental
Crystal
X2
Crystal
Oscillator
PLL
40/80M
25M
GND
OE/LAT
IDT™ / ICS™
PC PERIPHERAL CLOCK
1
ICS409
REV E 051310
ICS409
PC PERIPHERAL CLOCK
CLOCK SYNTHESIZER
Pin Assignment
OE /LAT
X1
X2
VDD
40/80M Frequency Selection
8
7
6
5
25M
25M
GND
40/80M
1
2
3
4
40/80M (pin 5)
0
1
Output Freq
40M
80M
Note: See below for operations of frequency selection
8 Pin (150 mil) S OIC
Pin Descriptions
Pin
Number
1
2
3
4
5
6
7
8
Pin
Name
OE/LAT
X1
X2
VDD
40/80M
GND
25M
25M
Pin
Type
Input
Input
Input
Power
Input/
Output
Power
Output
Output
Pin Description
Disables or latches 40/80 MHz output dependant on pin 5 level.
Crystal connection. Connect to 14.31818 MHz parallel mode crystal.
Crystal connection. Connect to 14.31818 MHz parallel mode crystal.
Connect to voltage supply.
40M or 80M selection pin and clock output (see below for operation).
Tri-state when OE/LAT is low.
Connect to ground.
25 MHz clock output.
25 MHz clock output.
External Components
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 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)
between the crystal and device. Crystal capacitors must
be connected from each of the pins X1 and X1 to
ground.
The value (in pF) of these crystal caps should equal (C
L
-6pF)*2. In this equation, C
L
= crystal load capacitance
Decoupling Capacitor
As with any high performance mixed-signal IC, the
ICS409 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.
IDT™ / ICS™
PC PERIPHERAL CLOCK
2
ICS409
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PC PERIPHERAL CLOCK
CLOCK SYNTHESIZER
in pF. Example: For a crystal with a 15 pF load
capacitance, each crystal capacitor would be 18 pF
[(15-6) x 2] = 18.
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 ICS409. This includes signal traces just
underneath the device, or on layers adjacent to the
ground plane layer used by the device.
PCB Layout Recommendations
For optimum device performance and lowest output
phase 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
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.
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
Selection of 40M/80M Clock
The 40/80M output clock is selected by a soft pull-up or
pull-down on 40/80M pin (pin 5). A rising edge on
OE/LAT latches in the high or low level on pin 5 which
starts the appropriate frequency.
Absolute Maximum Ratings
Stresses above the ratings listed below can cause permanent damage to the ICS409. 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.
Item
Supply Voltage, VDD
All Inputs and Outputs
Ambient Operating Temperature
Storage Temperature
Junction Temperature
Soldering Temperature
7V
Rating
-0.5 V to VDD+0.5 V
0 to +70
°
C
-65 to +150
°
C
175
°
C
260
°
C
Recommended Operation Conditions
Parameter
Ambient Operating Temperature
Power Supply Voltage (measured in respect to GND)
Min.
0
+3.00
Typ.
–
Max.
+70
+3.60
Units
°
C
V
IDT™ / ICS™
PC PERIPHERAL CLOCK
3
ICS409
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ICS409
PC PERIPHERAL CLOCK
CLOCK SYNTHESIZER
DC Electrical CharacteristicsDC Electrical Characteristics (continued)
VDD=3.3V ±10%
Parameter
Operating Voltage
Input High Voltage
Input Low Voltage
Output High Voltage
Output Low Voltage
Operating Supply Current
Short Circuit Current
Suggested Pull-up or
Pull-down resistor on pin 5
Symbol
VDD
V
IH
V
IL
V
OH
V
OL
IDD
I
OS
R
Conditions
Min.
3.0
Vdd-0.5
Typ.
Max.
3.6
0.5
Units
V
V
V
V
V
mA
mA
kΩ
I
OH
= -25 mA
I
OL
= 25 mA
No load
Each output
2.4
0.8
15
50
10
AC Electrical Characteristics
VDD = 3.3V ±10%
, Ambient Temperature 0 to +70× C
Parameter
Input Frequency
Output Rise Time
Output Fall Time
Output Clock Duty Cycle
Absolute Jitter, Short Term
t
OR
t
OF
0.8 to 2.0 V, C
L
=15 pF
2.0 to 0.8 V, C
L
=15 pF
at VDD/2
variation from mean
45
Symbol
Conditions
Min.
Typ.
14.318
0.8
0.6
50
Max. Units
MHz
ns
ns
55
%
ps
±
250
IDT™ / ICS™
PC PERIPHERAL CLOCK
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ICS409
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ICS409
PC PERIPHERAL CLOCK
CLOCK SYNTHESIZER
Package Outline and Package Dimensions
(8 pin SOIC, 150 Mil. Narrow Body)
Package dimensions are kept current with JEDEC Publication No. 95
Millimeters
Symbol
Min
Max
Inches
Min
Max
A
A1
B
C
D
E
In d e x
A re a
1.35
1.10
0.33
0.19
4.80
3.80
5.80
0.25
0.40
0°
1.75
0.25
0.51
0.25
5.00
4.00
6.20
0.50
1.27
8°
0.0532
0.0040
0.013
0.0075
.1890
0.1497
0.2284
0.010
0.016
0°
0.0688
0.0098
0.020
0.0098
.1968
0.1574
0.2440
0.020
0.050
8°
e
E
H
1.27 Basic
0.050 Basic
H
h
L
a
P in 1
D
h x 45
0
A
Q
e
b
c
Ordering Information
Part / Order Number
409MLF
409MLFT
Marking
409MLF
409MLF
Shipping Packaging
Tubes
Tape and Reel
Package
8-pin SOIC
8-pin SOIC
Temperature
0 to 70
°
C
0 to 70
°
C
Parts that are ordered with a "LF" suffix to the part number are the Pb-Free configuration and are RoHS compliant.
While the information presented herein has been checked for both accuracy and reliability, Integrated Device Technology (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.
IDT™ / ICS™
PC PERIPHERAL CLOCK
5
ICS409
REV E 051310
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