ICS651-03
MDS 651-03 A
1
Revision 112603
Integrated Circuit Systems
525 Race Street, San Jose, CA 95126
tel (408) 297-1201
www.icst.com
VOIP Clock Source
Description
The ICS651-03 is a low cost frequency generator
designed to support voice-over-internet protocol
(VOIP) applications. Using analog/digital
Phase-Locked Loop (PLL) techniques, the device uses
a standard fundamental mode, inexpensive crystal
input to produce four output clocks supporting DSP,
video encoder, and memory functions. To form a
complete VOIP clocking solution use the ICS651-02
companion device.
The device also has a power down feature that
tri-states the clock outputs and turns off the PLL when
the PDTS pin is taken low.
Features
Packaged in 16-pin TSSOP
Replaces multiple crystals and oscillators
Input crystal or clock frequency of 27 MHz
Fixed reference output frequency of 80 MHz
Fixed output frequency of 48 MHz
Fixed output frequency of 25 MHz
Reference output frequency of 27 MHz
Duty cycle of 40/60
Operating voltage of 3.3 V
Advanced, low power CMOS process
Block Diagram
X1
X2
PLL1
PLL2
Crystal
Oscillator/
Clock
Buffer
27 MHz
crystal
input
External capacitors
may be required.
VDD
GND
PDTS
(all outputs and PLLs)
80M
6
3
25M
48M
REF
VOIP Clock Source
MDS 651-03 A
2
Revision 112603
Integrated Circuit Systems
525 Race Street, San Jose, CA 95126
tel (408) 297-1201
www.icst.com
ICS651-03
Pin Assignment
Pin Descriptions
12
1
11
2
10
3
9
X1
4
GND
5
6
VDD
7
25M
8
GND
REF
VDD
VDD
VDD
VDD
80M
VDD
GND
16
15
14
13
48M
X2
16-pin (173 mil) TSSOP
PDTS
Pin
Number
Pin
Name
Pin
Type
Pin Description
1
X1
Input
Crystal connection. Connect to 27 MHz crystal input.
2
GND
Power
Connect to ground.
3
PDTS
Input
Powers down entire chip and tri-states outputs when low. Internal
pull-up resistor.
4
25M
Output
25 MHz clock output. Weak internal pull-down when tri-state.
5
GND
Power
Connect to ground.
6
VDD
Power
Connect to +3.3 V.
7
VDD
Power
Connect to +3.3 V.
8
48M
Output
48 MHz clock output. Weak internal pull down when tri-state.
9
80M
Output
80 MHz clock output. Weak internal pull down when tri-state.
10
GND
Power
Connect to ground.
11
VDD
Power
Connect to +3.3 V.
12
VDD
Power
Connect to +3.3 V.
13
VDD
Power
Connect to +3.3 V.
14
REF
Output
Reference 27 MHz output. Weak internal pull-down when tri-state.
15
VDD
Power
Connect to +3.3 V.
16
X2
Output
Crystal connection. Connect to 27 MHz crystal input.
VOIP Clock Source
MDS 651-03 A
3
Revision 112603
Integrated Circuit Systems
525 Race Street, San Jose, CA 95126
tel (408) 297-1201
www.icst.com
ICS651-03
External Components
Decoupling Capacitor
As with any high performance mixed-signal IC, the
ICS651-03 must be isolated from system power supply
noise to perform optimally.
A decoupling capacitor of 0.01F must be connected
between each VDD and the PCB ground plane.
Series Termination Resistor
Clock output traces over one inch should use series
termination. To series terminate a 50
trace (a
commonly used trace impedance), place a 33
resistor
in series with the clock line, as close to the clock output
pin as possible. The nominal impedance of the clock
output is 20
.
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 X2 to
ground.
The value (in pF) of these crystal caps should equal
(C
L
-6 pF)*2. In this equation, C
L
= 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 noise, the following guidelines should be
observed.
1) The 0.01F decoupling capacitors 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 capacitors and VDD pins. The
PCB trace to VDD pins 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
spaces, instead they should be separated and away
from other traces.
3) Place the 33
series termination resistor (if needed)
close to the clock output to minimize EMI.
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 ICS651-03. This includes signal traces
just underneath the device, or on layers adjacent to the
ground plane layer used by the device.
VOIP Clock Source
MDS 651-03 A
4
Revision 112603
Integrated Circuit Systems
525 Race Street, San Jose, CA 95126
tel (408) 297-1201
www.icst.com
ICS651-03
Absolute Maximum Ratings
Stresses above the ratings listed below can cause permanent damage to the ICS651-03. These ratings,
which are standard values for ICS 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.
Recommended Operation Conditions
DC Electrical Characteristics
Unless stated otherwise, VDD = 3.3V 5%, Ambient Temperature 0 to +70
C
Item
Rating
Supply Voltage, VDD
-0.5 V to 7 V
All Inputs and Outputs
-0.5 V to VDD+0.5 V
Ambient Operating Temperature
0 to +70
C
Storage Temperature
-65 to +150
C
Junction Temperature
175
C
Soldering Temperature
260
C
Parameter
Min.
Typ.
Max.
Units
Ambient Operating Temperature
0
+70
C
Power Supply Voltage (measured in respect to GND)
+3.135
+3.3
+3.465
V
Parameter
Symbol
Conditions
Min.
Typ.
Max.
Units
Operating Voltage
VDD
3.135
3.3
3.465
V
Supply Current
IDD
No load, PDTS=1
21
mA
Power Down Current
IDDPD
No load, PDTS=0
90
A
Input High Voltage
V
IH
PDTS
2
V
Input Low Voltage
V
IL
PDTS
0.8
V
Output High Voltage
V
OH
I
OH
= -4 mA
VDD-0.4
V
Output High Voltage
V
OH
I
OH
= -12 mA
2.4
V
Output Low Voltage
V
OL
I
OL
= 12 mA
0.4
V
Short Circuit Current
I
OS
Clock outputs
70
mA
Input Capacitance, inputs
C
IN
5
pF
VOIP Clock Source
MDS 651-03 A
5
Revision 112603
Integrated Circuit Systems
525 Race Street, San Jose, CA 95126
tel (408) 297-1201
www.icst.com
ICS651-03
AC Electrical Characteristics
Unless stated otherwise, VDD = 3.3V 5%, Ambient Temperature 0 to +70
C
Note 1: Measured with a 15 pF load.
Nominal Output Impedance
Z
OUT
20
Internal pull-up resistor
R
PU
PDTS pins
700
k
Internal pull-down resistor
R
PD
200
k
Parameter
Symbol
Conditions
Min.
Typ.
Max.
Units
Input Frequency
f
IN
27
MHz
Output Rise Time
t
OR
20% to 80% (Note 1)
1.0
ns
Output Fall Time
t
OF
80% to 20% (Note 1)
1.0
ns
Output Clock Duty Cycle
at VDD/2 (Note 1)
40
60
%
Absolute Clock Period Jitter
(Note 1)
100
ps
Frequency synthesis error
0
ppm
Output Enable Time
t
OE
PDTS high to output
locked to 1%
250
s
Output Disable Time
t
OD
PDTS low to tri-state
20
ns
Parameter
Symbol
Conditions
Min.
Typ.
Max.
Units
VOIP Clock Source
MDS 651-03 A
6
Revision 112603
Integrated Circuit Systems
525 Race Street, San Jose, CA 95126
tel (408) 297-1201
www.icst.com
ICS651-03
Thermal Characteristics
Marking Diagram
Notes:
1. ###### is the lot code.
2. YYWW is the last two digits of the year, and the week
number that the part was assembled.
Parameter
Symbol
Conditions
Min.
Typ.
Max.
Units
Thermal Resistance Junction to
Ambient
JA
Still air
78
C/W
JA
1 m/s air flow
70
C/W
JA
3 m/s air flow
68
C/W
Thermal Resistance Junction to Case
JC
37
C/W
1
8
9
16
651G-03
######
YYWW$$
VOIP Clock Source
MDS 651-03 A
7
Revision 112603
Integrated Circuit Systems
525 Race Street, San Jose, CA 95126
tel (408) 297-1201
www.icst.com
ICS651-03
Package Outline and Package Dimensions
(16-pin TSSOP, 173 Mil. Narrow Body)
Package dimensions are kept current with JEDEC Publication No. 95
Ordering Information
While the information presented herein has been checked for both accuracy and reliability, Integrated Circuit Systems (ICS)
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 ICS. ICS reserves the right to change any
circuitry or specifications without notice. ICS does not authorize or warrant any ICS product for use in life support devices or
critical medical instruments.
Part / Order Number
Marking
(both)
Shipping
packaging
Package
Temperature
ICS651G-03
(see gage 6)
Tubes
16-pin TSSOP
0 to +70
C
ICS651G-03T
Tape and Reel
16-pin TSSOP
0 to +70
C
IN D E X
A R E A
1 2
16
D
E 1
E
S E A T IN G
P LA N E
A
1
A
A
2
e
- C -
b
aaa
C
c
L
Millimeters
Inches
Symbol
Min
Max
Min
Max
A
--
1.20
--
0.047
A1
0.05
0.15
0.002
0.006
A2
0.80
1.05
0.032
0.041
b
0.19
0.30
0.007
0.012
C
0.09
0.20
0.0035
0.008
D
4.90
5.1
0.193
0.201
E
6.40 BASIC
0.252 BASIC
E1
4.30
4.50
0.169
0.177
e
0.65 Basic
0.0256 Basic
L
0.45
0.75
0.018
0.030
0
8
0
8
aaa
--
0.10
--
0.004
PDF 
ZIP