Integrated
Circuit
Systems, Inc.
ICS874005
PCI E
XPRESS
™
J
ITTER
A
TTENUATOR
F
EATURES
•
Five differential LVDS output pairs
•
One differential clock input
•
CLK and nCLK supports the following input types:
LVPECL, LVDS, LVHSTL, SSTL, HCSL
•
Output frequency range: 98MHz - 160MHz
•
Input frequency range: 98MHz - 128MHz
•
VCO range: 490MHz - 640MHz
•
Cycle-to-cycle jitter: 30ps (maximum)
•
3.3V operating supply
•
3 bandwidth modes allow the system designer to make
jitter attenuation/tracking skew design trade-offs
•
0°C to 70°C ambient operating temperature
•
Available in both standard and lead-free RoHS compliant
packages
G
ENERAL
D
ESCRIPTION
The ICS874005 is a high performance Diff-
erential-to-LVDS Jitter Attenuator designed for
HiPerClockS™
use in PCI Express systems. In some PCI
Express systems, such as those found in
desktop PCs, the PCI Express clocks are
generated from a low bandwidth, high phase noise PLL
frequency synthesizer. In these systems, a jitter attenuator
may be required to attenuate high frequency random and
deterministic jitter components from the PLL synthesizer
and from the system board. The ICS874005 has 3 PLL
bandwidth modes: 200kHz, 400kHz, and 800kHz. The
200kHz mode will provide maximum jitter attenuation, but
with higher PLL tracking skew and spread spectrum
modulation from the motherboard synthesizer may be
attenuated. The 400kHz provides an intermediate bandwidth
that can easily track triangular spread profiles, while
providing good jitter attenuation. The 800kHz bandwidth
provides the best tracking skew and will pass most spread
profiles, but the jitter attenuation will not be as good as the
lower bandwidth modes. Because some 2.5Gb serdes have
x20 multipliers while others have than x25 multipliers, the
874005 can be set for 1:1 mode or 5/4 multiplication mode
(i.e. 100MHz input/125MHz output) using the F_SEL pins.
IC
S
PLL B
ANDWIDTH
BW_SEL
0 = PLL Bandwidth: ~200kHz
Float = PLL Bandwidth: ~400kHz (Default)
1 = PLL Bandwidth: ~800kHz
The ICS874005 uses ICS 3
rd
Generation FemtoClock
TM
PLL technology to achive the lowest possible phase noise.
The device is packaged in a 24 Lead TSSOP package,
making it ideal for use in space constrained applications
such as PCI Express add-in cards.
B
LOCK
D
IAGRAM
OEA Pulldown
F_SELA Pulldown
BW_SEL Float
0 = ~200kHz
Float = ~400kHz
1 = ~800kHz
CLK Pulldown
nCLK Pullup
QA0
F_SELA
0 ÷5
(default)
1 ÷4
P
IN
A
SSIGNMENT
nQB2
nQA1
QA1
V
DDO
QA0
nQA0
MR
BW_SEL
V
DDA
F_SELA
V
DD
OEA
1
2
3
4
5
6
7
8
9
10
11
12
24
23
22
21
20
19
18
17
16
15
14
13
QB2
V
DDO
QB1
nQB1
QB0
nQB0
F_SELB
OEB
GND
GND
nCLK
CLK
nQA0
QA1
Phase
Detector
VCO
490 - 640MHz
nQA1
QB0
F_SELB
0 ÷5
(default)
1 ÷4
nQB0
QB1
nQB1
QB2
nQB2
M = ÷5
(fixed)
ICS874005
24-Lead TSSOP
4.40mm x 7.8mm x 0.92mm
package body
F_SELB Pulldown
MR Pulldown
OEB Pullup
874005AG
G Package
Top View
www.icst.com/products/hiperclocks.html
1
REV. A JANUARY 25, 2006
Integrated
Circuit
Systems, Inc.
ICS874005
PCI E
XPRESS
™
J
ITTER
A
TTENUATOR
Type
Output
Output
Power
Output
Output
Input
Description
Differential output pair. LVDS interface levels.
Differential output pair. LVDS interface levels.
Output supply pins.
Differential output pair. LVDS interface levels.
Inver ting differential feedback output.
Active HIGH Master Reset. When logic HIGH, the internal dividers are
reset causing the true outputs (nQx) to go low and the inver ted outputs
Pulldown
(Qx) to go high. When logic LOW, the internal dividers and the outputs
are enabled. LVCMOS/LVTTL interface levels.
Pullup/
PLL Bandwidth input. See Table 3B.
Pulldown
Analog supply pin.
Frequency select pin for QAx/nQAx outputs.
Pulldown
LVCMOS/LVTTL interface levels.
Core supply pin.
Output enable pin for QA pins. When HIGH, the QAx/nQAx outputs are
active. When LOW, the QAx/nQAx outputs are in a high impedance
Pullup
state. LVCMOS/LVTTL interface levels.
Pulldown Non-inver ting differential clock input.
Pullup
Inver ting differential clock input.
Power supply ground.
Output enable pin for QB pins. When HIGH, the QBx/nQBx outputs are
Pullup
active. When LOW, the QBx/nQBx outputs are in a high impedance
state. LVCMOS/LVTTL interface levels.
Frequency select pin for QBx/nQBx outputs.
Pulldown
LVCMOS/LVTTL interface levels.
Differential output pair. LVDS interface levels.
Differential output pair. LVDS interface levels.
T
ABLE
1. P
IN
D
ESCRIPTIONS
Number
1, 24
2, 3
4, 2 3
5, 6
6
7
Name
nQB2, QB2
nQA1, QA1
V
DDO
QA0, nQA0
nFB_OUT
MR
8
9
10
11
12
13
14
15, 16
17
18
19, 20
21, 22
BW_SEL
V
DDA
F_SELA
V
DD
OEA
CLK
nCLK
GND
OEB
F_SELB
nQB0, QB0
nQB1, QB1
Input
Power
Input
Power
Input
Input
Input
Power
Input
Input
Output
Output
NOTE:
Pullup
and
Pulldown
refer to internal input resistors. See Table 2, Pin Characteristics, for typical values.
T
ABLE
2. P
IN
C
HARACTERISTICS
Symbol
C
IN
R
PULLUP
R
PULLDOWN
Parameter
Input Capacitance
Input Pullup Resistor
Input Pulldown Resistor
Test Conditions
Minimum
Typical
4
51
51
Maximum
Units
pF
kΩ
kΩ
T
ABLE
3A. O
UTPUT
E
NABLE
F
UNCTION
T
ABLE
Inputs
OEA/OEB
0
1
HiZ
Enabled
Outputs
QAx/nQAx
QBx/nQBx
HiZ
Enabled
T
ABLE
3B. PLL B
ANDWIDTH
/PLL B
YPASS
C
ONTROL
Inputs
PLL_BW
0
1
Float
PLL
Bandwidth
~200kHz
~800kHz
~400kHz
REV. A JANUARY 25, 2006
874005AG
www.icst.com/products/hiperclocks.html
2
Integrated
Circuit
Systems, Inc.
ICS874005
PCI E
XPRESS
™
J
ITTER
A
TTENUATOR
4.6V
-0.5V to V
DD
+ 0.5 V
-0.5V to V
DDO
+ 0.5V
70°C/W (0 lfpm)
-65°C to 150°C
NOTE: Stresses beyond those listed under Absolute
Maximum Ratings may cause permanent damage to the
device. These ratings are stress specifications only. Functional
operation of product at these conditions or any conditions be-
yond those listed in the
DC Characteristics
or
AC Character-
istics
is not implied. Exposure to absolute maximum rating
conditions for extended periods may affect product reliability.
A
BSOLUTE
M
AXIMUM
R
ATINGS
Supply Voltage, V
DD
Inputs, V
I
Outputs, V
O
Package Thermal Impedance,
θ
JA
Storage Temperature, T
STG
T
ABLE
4A. P
OWER
S
UPPLY
DC C
HARACTERISTICS
,
V
DD
= V
DDA
= V
DDO
= 3.3V±5%, T
A
= 0°C
TO
70°C
Symbol
V
DD
V
DDA
V
DDO
I
DD
I
DDA
I
DDO
Parameter
Core Supply Voltage
Analog Supply Voltage
Output Supply Voltage
Power Supply Current
Analog Supply Current
Output Supply Current
Test Conditions
Minimum
3.135
3.135
3.135
Typical
3.3
3.3
3.3
Maximum
3.465
3.465
3.465
85
15
115
Units
V
V
V
mA
mA
mA
T
ABLE
4B. LVCMOS/LVTTL DC C
HARACTERISTICS
,
V
DD
= V
DDA
= V
DDO
= 3.3V±5%, T
A
= 0°C
TO
70°C
Symbol Parameter
V
IH
Input High Voltage
OEA, OEB, MR,
F_SELA, F_SELB
BW_SEL
V
IL
V
IM
I
IH
Input Low Voltage
Input Mid Voltage
Input High Current
OEA, OEB, MR,
F_SELA, F_SELB
BW_SEL
BW_SEL
OEA, OEB
F_SELA, F_SELB
MR, BW_SEL
BW_SEL,
OEA, OEB
MR,
F_SELA, F_SELB
V
DD
= V
IN
= 3.465V
V
DD
= V
IN
= 3.465V
V
DD
= 3.465V, V
IN
= 0V
V
DD
= 3.465V, V
IN
= 0V
-150
-5
V
DD
/2 - 0.1
Test Conditions
Minimum
2
V
DD
- 0.4
-0.3
0.8
0.4
V
DD
/2 + 0.1
5
150
Typical
Maximum
V
DD
+ 0.3
Units
V
V
V
V
V
µA
µA
µA
µA
I
IL
Input Low Current
874005AG
www.icst.com/products/hiperclocks.html
3
REV. A JANUARY 25, 2006
Integrated
Circuit
Systems, Inc.
ICS874005
PCI E
XPRESS
™
J
ITTER
A
TTENUATOR
Test Conditions
CLK
nCLK
CLK
nCLK
V
DD
= V
IN
= 3.465V
V
DD
= V
IN
= 3.465V
V
DD
= V
IN
= 3.465V
V
DD
= V
IN
= 3.465V
-150
0.15
1.3
V
DD
- 0.85
V
V
5
150
µA
Minimum
Typical
Maximum
150
Units
µA
T
ABLE
4C. D
IFFERENTIAL
DC C
HARACTERISTICS
,
V
DD
= V
DDA
= V
DDO
= 3.3V±5%, T
A
= 0°C
TO
70°C
Symbol
I
IH
I
IL
V
PP
Parameter
Input High Current
Input Low Current
Peak-to-Peak Input Voltage
V
CMR
Common Mode Input Voltage; NOTE 1, 2
GND + 0.5
NOTE 1: Common mode voltage is defined as V
IH
.
NOTE 2: For single ended applications, the maximum input voltage for CLK, nCLK is V
DD
+ 0.3V.
T
ABLE
4D. LVDS DC C
HARACTERISTICS
,
V
DD
= V
DDA
= V
DDO
= 3.3V±5%, T
A
= 0°C
TO
70°C
Symbol
V
OD
Δ
V
OD
V
OS
Δ
V
OS
Parameter
Differential Output Voltage
V
OD
Magnitude Change
Offset Voltage
V
OS
Magnitude Change
1.2
1.35
Test Conditions
Minimum
275
Typical
375
Maximum
485
50
1.5
50
Units
mV
mV
V
mV
T
ABLE
5. AC C
HARACTERISTICS
,
V
DD
= V
DDA
= V
DDO
= 3.3V±5%, T
A
= 0°C
TO
70°C
Symbol
f
MAX
t
jit(cc)
t
sk(o)
t
R
/ t
F
Parameter
Output Frequency
Cycle-to-Cycle Jitter, NOTE 1
Output Skew; NOTE 2, 3
Output Rise/Fall Time
20% to 80%
300
Test Conditions
Minimum
98
15
Typical
Maximum
160
30
90
550
52
Units
MH z
ps
ps
ps
%
odc
Output Duty Cycle
48
NOTE 1: This parameter is defined in accordance with JEDEC Standard 65.
NOTE 2: Defined as skew between outputs at the same supply voltage and with equal load conditions.
Measured at V
DDO
/2.
NOTE 3: These parameters are guaranteed by characterization. Not tested in production.
874005AG
www.icst.com/products/hiperclocks.html
4
REV. A JANUARY 25, 2006
Integrated
Circuit
Systems, Inc.
ICS874005
PCI E
XPRESS
™
J
ITTER
A
TTENUATOR
P
ARAMETER
M
EASUREMENT
I
NFORMATION
V
DD,
V
DDO
V
DDA
V
DD
3.3V±5%
POWER SUPPLY
Float GND
+
–
Qx
SCOPE
nCLK
V
PP
LVDS
nQx
Cross Points
V
CMR
CLK
GND
3.3V LVDS O
UTPUT
L
OAD
AC T
EST
C
IRCUIT
nQA0, nQA1
nQB0:nQB2
QA0, QA1
QB0:QB2
D
IFFERENTIAL
I
NPUT
L
EVEL
nQx
Qx
➤
t
jit(cc) =
t
cycle n –
t
cycle n+1
1000 Cycles
C
YCLE
-
TO
-C
YCLE
J
ITTER
80%
Clock
Outputs
20%
t
R
t
F
O
UTPUT
R
ISE
/F
ALL
T
IME
V
DD
out
DC Input
LVDS
100
V
OD
/Δ V
OD
out
➤
out
V
OS
/Δ V
OS
D
IFFERENTIAL
O
UTPUT
V
OLTAGE
S
ETUP
874005AG
O
FFSET
V
OLTAGE
S
ETUP
www.icst.com/products/hiperclocks.html
5
REV. A JANUARY 25, 2006
➤
➤
➤
➤
t
cycle n
t
cycle
➤
n+1
➤
nQy
Qy
tsk(o)
O
UTPUT
S
KEW
nQA0, nQA1
nQB0:nQB2
80%
V
SW I N G
20%
QA0, QA1
QB0:QB2
t
PW
t
PERIOD
odc =
t
PW
t
PERIOD
x 100%
O
UTPUT
D
UTY
C
YCLE
/P
ULSE
W
IDTH
/P
ERIOD
V
DD
out
➤
DC Input
LVDS
➤
