FEMTOCLOCKS™ CRYSTAL-TO-LVDS
CLOCK GENERATOR
ICS844021I-01
G
ENERAL
D
ESCRIPTION
The ICS844021I-01 is an Ether net Clock Generator. The
ICS844021I-01 uses an 18pF parallel resonant crystal over the
range of 24.5MHz – 34MHz. For Ethernet appli-cations, a 25MHz
crystal is used. The ICS844021I-01 has excellent <1ps phase
jitter performance, over the 1.875MHz – 20MHz integration
range. The ICS844021I-01 is packaged in a small 8-pin TSSOP,
making it ideal for use in systems with limited board space.
F
EATURES
•
One Differential LVDS output
•
Crystal oscillator interface, 18pF parallel resonant crystal
(24.5MHz
–
34MHz)
•
Output frequency range: 122.5MHz
–
170MHz
•
VCO range: 490MHz
–
680MHz
•
RMS phase jitter @ 125MHz, using a 25MHz crystal
(1.875MHz
–
20MHz): 0.32ps (typical) @ 3.3V
•
3.3V or 2.5V operating supply
•
-40°C to 85°C ambient operating temperature
•
Available in both standard (RoHS 5) and lead-free (RoHS 6)
packages
C
OMMON
C
ONFIGURATION
T
ABLE
- Gb E
THERNET
Inputs
Crystal Frequency (MHz)
25
26.666
33.33
M
20
20
20
N
4
4
4
Multiplication
Value M/N
5
5
5
Output Frequency
(MHz)
125
133.33
166.66
B
LOCK
D
IAGRAM
OE
Pullup
P
IN
A
SSIGNMENT
V
DDA
GND
XTAL_OUT
XTAL_IN
1
2
3
4
8
7
6
5
V
DD
Q
nQ
OE
XTAL_IN
OSC
XTAL_OUT
Phase
Detector
VCO
490MHz - 680MHz
N = ÷4
(fixed)
Q
nQ
ICS844021I-01
8-Lead TSSOP
4.40mm x 3.0mm x 0.925mm
package body
G Package
Top View
M = ÷20
(fixed)
IDT
™
/ ICS
™
LVDS CLOCK GENERATOR
1
ICS844021BGI-01 REV. A NOVEMBER 6, 2012
ICS844021I-01
FEMTOCLOCKS™ CRYSTAL-TO-LVDS CLOCK GENERATOR
T
ABLE
1. P
IN
D
ESCRIPTIONS
Number
1
2
3,
4
5
6, 7
8
Name
V
DDA
GND
XTAL_OUT,
XTAL_IN
OE
nQ, Q
V
DD
Power
Power
Input
Input
Output
Power
Pullup
Type
Description
Analog supply pin.
Power supply ground.
Crystal oscillator interface. XTAL_IN is the input,
XTAL_OUT is the output.
Output enable pin. When HIGH, Q/nQ output is active.
When LOW, the Q/nQ output is in a high impedance state.
LVCMOS/LVTTL interface levels.
Differential clock outputs. LVDS interface levels.
Core supply pin.
NOTE:
Pullup
refers to internal input resistors. See Table 2, Pin Characteristics, for typical values.
T
ABLE
2. P
IN
C
HARACTERISTICS
Symbol
C
IN
R
PULLUP
Parameter
Input Capacitance
Input Pullup Resistor
Test Conditions
Minimum
Typical
4
51
Maximum
Units
pF
kΩ
IDT
™
/ ICS
™
LVDS CLOCK GENERATOR
2
ICS844021BGI-01 REV. A NOVEMBER 6, 2012
ICS844021I-01
FEMTOCLOCKS™ CRYSTAL-TO-LVDS CLOCK GENERATOR
A
BSOLUTE
M
AXIMUM
R
ATINGS
Supply Voltage, V
DD
Inputs, V
I
Outputs, I
O
(LVDS)
Continuous Current
Surge Current
4.6V
-0.5V to V
DD
+ 0.5 V
10mA
15mA
NOTE: Stresses beyond those listed under Absolute
Maximum Ratings may cause per manent damage to the
device. These ratings are stress specifications only. Functional
operation of product at these conditions or any conditions
beyond those listed in the
DC Characteristics
or
AC Char-
acteristics
is not implied. Exposure to absolute maximum rating
Package Thermal Impedance,
θ
JA
129.5°C/W (0 mps)
Storage Temperature, T
STG
-65°C to 150°C
conditions for extended periods may affect product reliability.
T
ABLE
3A. P
OWER
S
UPPLY
DC C
HARACTERISTICS
,
V
DD
= 3.3V±5%, T
A
= -40°C
TO
85°C
Symbol
V
DD
V
DDA
I
DD
I
DDA
Parameter
Core Supply Voltage
Analog Supply Voltage
Power Supply Current
Analog Supply Current
Test Conditions
Minimum
3.135
V
DD
– 0.10
Typical
3.3
3.3
Maximum
3.465
V
DD
75
10
Units
V
V
mA
mA
T
ABLE
3B. P
OWER
S
UPPLY
DC C
HARACTERISTICS
,
V
DD
= 2.5V±5%, T
A
= -40°C
TO
85°C
Symbol
V
DD
V
DDA
I
DD
I
DDA
Parameter
Core Supply Voltage
Analog Supply Voltage
Power Supply Current
Analog Supply Current
Test Conditions
Minimum
2.375
V
DD
– 0.10
Typical
2.5
2.5
Maximum
2.625
V
DD
70
10
Units
V
V
mA
mA
T
ABLE
3C. LVCMOS/LVTTL DC C
HARACTERISTICS
,
V
DD
= 3.3V±5%
OR
2.5V±5%, T
A
= -40°C
TO
85°C
Symbol
V
IH
V
IL
I
IH
I
IL
Parameter
Input High Voltage
Input Low Voltage
Input High Current
Input Low Current
Test Conditions
V
DD
= 3.3V
V
DD
= 2.5V
V
DD
= 3.3V
V
DD
= 2.5V
V
DD
= V
IN
= 3.465V or 2.625V
V
DD
= 3.465V or 2.625V, V
IN
= 0V
-150
Minimum
2
1.7
-0.3
-0.3
Typical
Maximum
V
DD
+ 0.3
V
DD
+ 0.3
0.8
0.7
5
Units
V
V
V
V
µA
µA
IDT
™
/ ICS
™
LVDS CLOCK GENERATOR
3
ICS844021BGI-01 REV. A NOVEMBER 6, 2012
ICS844021I-01
FEMTOCLOCKS™ CRYSTAL-TO-LVDS CLOCK GENERATOR
T
ABLE
3D. LVDS DC C
HARACTERISTICS
,
V
DD
= 3.3V±5%, T
A
= -40°C
TO
85°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
1.15
Test Conditions
Minimum
275
Typical
Maximum
425
50
1.45
50
Units
mV
mV
V
mV
NOTE: Please refer to Parameter Measurement Information for output information.
T
ABLE
3E. LVDS DC C
HARACTERISTICS
,
V
DD
= 2.5V±5%, T
A
= -40°C
TO
85°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
1.05
Test Conditions
Minimum
215
Typical
Maximum
430
50
1.45
50
Units
mV
mV
V
mV
NOTE: Please refer to Parameter Measurement Information for output information.
T
ABLE
4. C
RYSTAL
C
HARACTERISTICS
Parameter
Mode of Oscillation
Frequency
Equivalent Series Resistance (ESR)
Shunt Capacitance
NOTE: It is not recommended to overdrive the crystal input with an external clock.
24.5
Test Conditions
Minimum
Typical
Fundamental
34
50
7
MHz
Ω
pF
Maximum
Units
T
ABLE
5. AC C
HARACTERISTICS
,
V
DD
= 3.3V±5%
OR
2.5V±5%, T
A
= -40°C
TO
85°C
Symbol
f
OUT
Parameter
Output Frequency
RMS Phase Jitter ( Random);
NOTE 1
Output Rise/Fall Time
Test Conditions
125MHz @ Integration Range:
1.875MHz - 20MHz
20% to 80%
Minimum
122.5
0.32
200
48
400
52
Typical
Maximum
170
Units
MHz
ps
ps
%
t
jit(Ø)
t
R
/ t
F
odc
Output Duty Cycle
NOTE 1: Please refer to the Phase Noise Plots following this section.
IDT
™
/ ICS
™
LVDS CLOCK GENERATOR
4
ICS844021BGI-01 REV. A NOVEMBER 6, 2012
ICS844021I-01
FEMTOCLOCKS™ CRYSTAL-TO-LVDS CLOCK GENERATOR
T
YPICAL
P
HASE
N
OISE AT
125MH
Z
@ 3.3V
125MHz
RMS Phase Jitter (Random)
1.875MHz to 20MHz = 0.32ps (typical)
Ethernet Filter
N
OISE
P
OWER
dBc
Hz
Raw Phase Noise Data
Phase Noise Result by adding
Ethernet Filter to raw data
O
FFSET
F
REQUENCY
(H
Z
)
T
YPICAL
P
HASE
N
OISE AT
125MH
Z
@ 2.5V
125MHz
RMS Phase Jitter (Random)
1.875MHz to 20MHz = 0.32ps (typical)
Ethernet Filter
N
OISE
P
OWER
dBc
Hz
Raw Phase Noise Data
Phase Noise Result by adding
Ethernet Filter to raw data
O
FFSET
F
REQUENCY
(H
Z
)
IDT
™
/ ICS
™
LVDS CLOCK GENERATOR
5
ICS844021BGI-01 REV. A NOVEMBER 6, 2012
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