MDS 556-01 B
1
Revision 020204
I n t e gra t e d C i r c u i t S y s t e m s
5 2 5 R a c e S t r e e t , S a n J o s e, C A 9 5 1 2 6
t e l ( 4 0 8 ) 2 9 7 - 1 2 0 1
w w w. i c s t . c o m
B
ROADCOM
25 MH
Z
LVDS C
LOCK
ICS556-01
Description
The ICS556-01 is a clock oscillator with LVDS outputs.
Using a standard 25 MHz crystal, the device outputs a
.25 mHz (reference) differential output clock. The
operation voltage is 2.5 V to support today's popular
interfaces. The termination resistor is off-chip.
Features
Packaged in 8-pin TSSOP
Requires no external components
Low Phase Jitter: <1 ps from 10 kHz to 10 MHz
Differential LVDS outputs
Operating voltage of 2.5 V.
Advanced, low power, sub-micron CMOS process
Block Diagram
X1
X2
Crystal
Oscillator
25 MHz Crystal
GND
VDD
CLK
CLK
2
OE
100
MDS 556-01 B
2
Revision 020204
I n t e gr a t e d C i r c u i t S y s t e m s
5 2 5 R a c e S t r e e t , S a n J o s e, C A 9 5 1 2 6
t e l ( 4 0 8 ) 2 9 7 - 1 2 0 1
w w w. i c s t . c o m
Broadcom 25 MHz LVDS Clock
ICS556-01
Pin Assignment
Pin Descriptions
External Component Selection
The ICS556-01 requires a minimum number of external
components for proper operation. A 100
termination
resistor between CLK and CLK is provided on-chip.
Decoupling Capacitors
A decoupling capacitor of 0.01
F should be connected
between VDD and GND on pins 2 and 3 as close to the
ICS556-01 as possible. For optimum device
performance, the decoupling capacitor should be
mounted on the component side of the PCB. Avoid the
use of vias in the decoupling circuit.
LVDS Driver Termination
A general LVDS interface is shown in Figure 2. In a 100
differential transmission line environment, LVDS drivers
require a matched load termination of 100
across near
the receiver input. For a multiple LVDS outputs buffer, if
only partial outputs are used, it is recommended to
terminate the un-used outputs.
X 2
X 1
V D D
G N D
C L K
1
2
3
4
8
7
6
5
I C S 5 5 6 - 0 1
8 P i n ( 1 7 3 m i l ) T S S O P o r S O I C
C L K
G N D
O E
Pin
Number
Pin
Name
Pin
Type
Pin Description
1
X1
Input
Crystal connection.
2
VDD
Power
Power supply. Connect to 2.5 V.
3
GND
Power
Connect to ground.
4
GND
Power
Connect to ground.
5
CLK
Output
Inverting differential clock output.
6
CLK
Power
Differential clock output.
7
OE
Input
Output Enable. Internal pull-up resistor.
8
X2
Input
Crystal connection.
F I G U R E 2 . T Y P I C A L L V D S
D R I V E R T E R M I N A T I O N
R1
100 ohm
+
-
2.5V
2.5V
100 Ohm Differential Transmission Line
LVDS_Driver
MDS 556-01 B
3
Revision 020204
I n t e gr a t e d C i r c u i t S y s t e m s
5 2 5 R a c e S t r e e t , S a n J o s e, C A 9 5 1 2 6
t e l ( 4 0 8 ) 2 9 7 - 1 2 0 1
w w w. i c s t . c o m
Broadcom 25 MHz LVDS Clock
ICS556-01
Quartz Crystal
The ICS556-01 25 MHz LVDS Clock utilizes an
external crystal to generate a low phase noise output.
To assure the best system performance 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.
The frequency of oscillation of a quartz crystal is
determined by its "cut" and by the load capacitors
connected to it. The crystal specified for use with the
ICS556-01 is designed to have zero frequency error
when the total of on-chip plus stray capacitance is 5 pF.
Recommended Crystal Parameters:
Initial Accuracy of 25
C
20 ppm
Temperature Stability
20 ppm
Load Capacitance5 pf
Shunt Capacitance, C02 pF Max
Equivalent Series Resistance80
Max
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 ICS556-01. 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.
The value (in pF) of these crystal caps should equal
(C
L
- 12 pF)*2. In this equation, C
L
=crystal load
capacitance in pF. Example: or a crystal with a 16 pF
load capacitance, each crystal capacitor would be 8 pF
[(16-12) x 2] = 8.
Absolute Maximum Ratings
Stresses above the ratings listed below can cause permanent damage to the ICS556-01. 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
Item
Rating
Supply Voltage, VDD
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
Soldering Temperature
260
C
Parameter
Min.
Typ.
Max.
Units
Ambient Operating Temperature
0
+70
C
Power Supply Voltage (measured in respect to GND)
+2.375
+2.625
V
Reference crystal parameters
Refer to page 3
MDS 556-01 B
4
Revision 020204
I n t e gr a t e d C i r c u i t S y s t e m s
5 2 5 R a c e S t r e e t , S a n J o s e, C A 9 5 1 2 6
t e l ( 4 0 8 ) 2 9 7 - 1 2 0 1
w w w. i c s t . c o m
Broadcom 25 MHz LVDS Clock
ICS556-01
DC Electrical Characteristics
VDD=2.5 V 5%
, Ambient temperature 0 to +70
C, unless stated otherwise
Note 1: Outputs terminated with 50
to VDD/2
AC Electrical Characteristics
VDD = 2.5 V 5%, Ambient Temperature 0 to +70
C, unless stated otherwise
Parameter
Symbol
Conditions
Min.
Typ.
Max.
Units
Operating Voltage
VDD
2.375
2.625
V
Output High Voltage
V
OH
Note 1
1.375
V
Output Low Voltage
V
OL
Note 1
1.125
V
Output High Voltage (CMOS
Level)
V
OH
I
OH
= -4 mA
VDD-0.4
V
Operating Supply Current
IDD
No load, OE = 1
5.3
mA
No load, OE = 0
1.7
mA
Parameter
Conditions
Min.
Typ.
Max. Units
Input Frequency
25
MHz
Output Frequency
25
MHz
Differential Output Voltages (V
OD
)
250
350
450
mV
V
OD
V
OD
Magnitude Change
-40
0
40
mV
Offset Voltage (V
OS
)
1.125
1.25
1.375
V
V
OS
V
OS
Magnitude Change
3
25
mV
Differential Output Short Circuit Current (I
OSD
)
-3.5
mA
Output Short Circuit Current (I
OS
)
-3.5
mA
Output Rise Time
20% to 80%, no load
0.8
1.2
ns
Output Fall Time
20% to 80%, no load
0.8
1.2
ns
Output Clock Duty Cycle
Measured at 1.25 V,
C
L
=5 pF
45
50
55
%
Maximum Output Jitter (p-p)
C
L
=5 pF
40
ps
Phase Jitter (RMS)
Phase Noise integrated
from 10 kHz to 10 MHz
1.8
2.5
ps
MDS 556-01 B
5
Revision 020204
I n t e gr a t e d C i r c u i t S y s t e m s
5 2 5 R a c e S t r e e t , S a n J o s e, C A 9 5 1 2 6
t e l ( 4 0 8 ) 2 9 7 - 1 2 0 1
w w w. i c s t . c o m
Broadcom 25 MHz LVDS Clock
ICS556-01
Parameter Measurement Information
2.5V O
UTPUT
L
OAD
AC T
EST
C
IRCUIT
LVDS
V
DD
= 2.5V5%
SCOPE
50
50
Z = 50
Z = 50
Qx
nQx
t
PW
& t
PERIOD
nCLK
CLK
t
PERIOD
Pulse Width
P
HASE
J
ITTER
nCLK
CLK
t(
)
t
jit(
) =
t
(
) -
t
(
)
mean
= Phase Jitter
V
OH
V
OL
D
IFFERENTIAL
I
NPUT
L
EVEL
VOD
Cross Points
VDD
VOS
nCLK
CLK
GND
Clock
Outputs
80%
80%
20%
20%
t
OR
t
OF
O
UTPUT
R
ISE
/F
ALL
T
IME
V
OD
V
O S
S
E T U P
L V D S
V
D D
5 0
o u t
D C In p u t
V
O S
/
V
O S
o u t
5 0
V
OD
S
ETUP
LVDS
V
DD
100
out
out
DC Input
V
OD
/
V
OD
MDS 556-01 B
6
Revision 020204
I n t e gr a t e d C i r c u i t S y s t e m s
5 2 5 R a c e S t r e e t , S a n J o s e, C A 9 5 1 2 6
t e l ( 4 0 8 ) 2 9 7 - 1 2 0 1
w w w. i c s t . c o m
Broadcom 25 MHz LVDS Clock
ICS556-01
Package Outline and Package Dimensions (8-pin TSSOP)
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
Shipping
packaging
Package
Temperature
ICS556G-01
556G-01
Tubes
8-pin TSSOP
0 to +70
C
ICS556G-01T
556G-01
Tape and Reel
8-pin TSSOP
0 to +70
C
IN D E X
A R E A
1 2
8
D
E 1
E
S E A T IN G
P LA N E
A
1
A
A
2
e
- C -
b
a a a
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
2.90
3.10
0.114
0.122
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