FemtoClock
®
Crystal-to-3.3V LVPECL
Clock Generator
843251I-04
DATA SHEET
General Description
The 843251I-04 is a 10Gb/12Gb Ethernet Clock Generator. The
843251I-04 can synthesize 10 Gigabit Ethernet and 12 Gigabit
Ethernet with a 25MHz crystal. It can also generate SATA and 10Gb
Fibre Channel reference clock frequencies with the appropriate
choice of crystals. The 843251I-04 has excellent phase jitter
performance and is packaged in a small 8-pin TSSOP, making it
ideal for use in systems with limited board space.
Features
•
•
•
•
•
•
•
•
•
One differential 3.3V LVPECL output
Crystal oscillator interface designed for
18pF parallel resonant crystal
Crystal input frequency range: 19.33MHz – 30MHz
Output frequency range: 145MHz – 187.5MHz
VCO range: 580MHz – 750MHz
RMS phase jitter @ 156.25MHz, (1.875MHz – 20MHz):
0.39ps (typical)
Full 3.3V supply mode
-40°C to 85°C ambient operating temperature
Available in lead-free (RoHS 6) package
Configuration Table with 25MHz Crystal
Inputs
Crystal Frequency
(MHz))
25
25
Feedback Divide
30
25
VCO Frequency
(MHz)
750
625
N Output Divide
4
4
Output Frequency
(MHz)
187.5
156.25
Application
12 Gigabit Ethernet
10 Gigabit Ethernet
Configuration Table with Selectable Crystals
Inputs
Crystal Frequency
(MHz))
20
21.25
24
25.5
30
Feedback Divide
30
30
25
25
25
VCO Frequency
(MHz)
600
637.5
600
637.5
750
N Output Divide
4
4
4
4
4
Output Frequency
(MHz)
150
159.375
150
159.375
187.5
Application
SATA
10 Gigabit Fibre Channel
SATA
10 Gigabit Fibre Channel
12 Gigabit Fibre Channel
Block Diagram
XTAL_IN
Pin Assignment
Phase
Detector
VCO
580MHz-750MHz
OSC
XTAL_OUT
DIV. N
÷4
nQ
Q
V
CCA
V
EE
XTAL_OUT
XTAL_IN
1
2
3
4
8
7
6
5
V
CC
Q
nQ
FREQ_SEL
0 = ÷25
(default)
1 = ÷30
FREQ_SEL
843251I-04
8 Lead TSSOP
4.40mm x 3.0mm package body
843251I-04 REVISION B 10/29/15
1
©2015 Integrated Device Technology, Inc.
843251I-04 DATA SHEET
Pin Description and Pin Characteristic Tables
Table 1. Pin Descriptions
Number
1
2
3, 4
5
6, 7
8
Name
V
CCA
V
EE
XTAL_OUT
XTAL_IN
FREQ_SEL
nQ, Q
V
CC
Unused
Power
Input
Input
Output
Power
Pulldown
Type
Description
Analog supply pin.
Negative supply pin.
Crystal oscillator interface. XTAL_IN is the input, XTAL_OUT is the output.
Frequency select pin. LVCMOS/LVTTL interface levels.
Differential output pair. LVPECL interface levels.
Core supply pin.
NOTE: Pulldown refers to internal input resistors. See Table 2, Pin Characteristics, for typical values.
Table 2. Pin Characteristics
Symbol
C
IN
R
PULLDOWN
Parameter
Input Capacitance
Input Pulldown Resistor
Test Conditions
Minimum
Typical
4
51
Maximum
Units
pF
k
FEMTOCLOCK
®
CRYSTALl-TO-3.3V LVPECL CLOCK GENERATOR
2
REVISION B 10/29/15
843251I-04 DATA SHEET
Absolute Maximum Ratings
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 beyond
those listed in the
DC Characteristics or AC Characteristics
is not implied. Exposure to absolute maximum rating conditions for
extended periods may affect product reliability.
Item
Supply Voltage, V
CC
Inputs, V
I
Outputs, I
O
Continuous Current
Surge Current
Package Thermal Impedance,
JA
Storage Temperature, T
STG
Rating
4.6V
-0.5V to V
CC
+ 0.5V
50mA
100mA
129.5C/W (0 mps)
-65C to 150C
DC Electrical Characteristics
Table 3A. Power Supply DC Characteristics,
V
CC
= 3.3V ± 5%, V
EE
= 0V, T
A
= -40°C to 85°C
Symbol
V
CC
V
CCA
I
EE
i
CCA
Parameter
Positive Supply Voltage
Analog Supply Voltage
Power Supply Current
Analog Supply Current
Test Conditions
Minimum
3.135
V
CC
– 0.13
Typical
3.3
3.3
Maximum
3.465
V
CC
70
13
Units
V
V
mA
mA
Table 3B. LVCMOS/LVTTL DC Characteristics,
V
CC
= 3.3V ± 5%, V
EE
= 0V, 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
V
CC
= V
IN
= 3.465V
V
CC
= 3.465V, V
IN
= 0V
-5
Test Conditions
Minimum
2
-0.3
Typical
Maximum
V
CC
+ 0.3
0.8
150
Units
V
V
µA
µA
Table 3C. LVPECL DC Characteristics,
V
CC
= 3.3V ± 5%, V
EE
= 0V, T
A
= -40°C to 85°C
Symbol
V
OH
V
OL
V
SWING
Parameter
Output High Current; NOTE 1
Output Low Current; NOTE 1
Peak-to-Peak Output Voltage Swing
Test Conditions
Minimum
V
CC
– 1.4
V
CC
– 2.0
0.6
Typical
Maximum
V
CC
– 0.9
V
CC
– 1.7
1.0
Units
µA
µA
V
NOTE 1: Outputs termination with 50 to V
CC
– 2V.
REVISION B 10/29/15
3
FEMTOCLOCK
®
CRYSTALL-TO-3.3V LVPECL CLOCK GENERATOR
843251I-04 DATA SHEET
Table 4. Crystal Characteristics
Parameter
Mode of Oscillation
Frequency
Equivalent Series Resistance (ESR)
Shunt Capacitance
19.33
Test Conditions
Minimum
Typical
Fundamental
30
50
7
MHz
Maximum
Units
pF
AC Electrical Characteristics
Table 5. AC Characteristics,
V
CC
= 3.3V ± 5%, V
EE
= 0V, T
A
= -40°C to 85°C
Symbol
f
OUT
Parameter
Output Frequency
RMS Phase Jitter, Random;
NOTE 1
Output Rise/Fall Time
Output Duty Cycle
156.25MHz,
(Integration Range: 1.875MHz – 20MHz)
187.5MHz,
(Integration Range: 1.875MHz – 20MHz)
20% to 80%
285
48
Test Conditions
Minimum
145
0.39
0.40
415
52
Typical
Maximum
187.5
Units
MHz
ps
ps
ps
%
tjit(Ø)
t
R
/ t
F
odc
NOTE: Electrical parameters are guaranteed over the specified ambient operating temperature range, which is established when the
device is mounted in a test socket with maintained transverse airflow greater than 500 lfpm. The device will meet specifications after
thermal equilibrium has been reached under these conditions.
NOTE 1: Please refer to Phase Noise Plots.
FEMTOCLOCK
®
CRYSTALl-TO-3.3V LVPECL CLOCK GENERATOR
4
REVISION B 10/29/15
843251I-04 DATA SHEET
Typical Phase Noise at 187.5MHz
187.5MHz
RMS Phase Jitter (Random)
1.875MHz to 20MHz = 0.40ps (typical)
Noise Power
dBc
Hz
Raw Phase Noise Data
Offset Frequency (Hz)
REVISION B 10/29/15
5
FEMTOCLOCK
®
CRYSTALL-TO-3.3V LVPECL CLOCK GENERATOR
➝
Phase Noise Result by adding a
12Gb Ethernet filter to raw data
➝
12Gb Ethernet Filter
➝
京公网安备 11010802033920号
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