FemtoClock
®
Crystal-to-3.3V LVPECL
Clock Generator
843021
DATA SHEET
General Description
The 843021 is a Gigabit Ethernet Clock Generator. The ICS84302
uses a 25MHz crystal to synthesize 125MHz. The 843021has
excellent phase jitter performance, over the 1.875MHz – 20MHz
integration range. The 843021is 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 22.4MHz – 28MHz, 18pF
parallel resonant crystal
Output frequency range: 112MHz – 140MHz
VCO range: 560MHz – 700MHz
Output duty cycle range: 49% – 51%
RMS phase jitter at 125MHz, using a 25MHz crystal
(1.875MHz – 20MHz): 0.650ps (typical)
Offset
Noise Power
100Hz ..............-94.2 dBc/Hz
1kHz ..............-122.8 dBc/Hz
10kHz ..............-132.2 dBc/Hz
100kHz ..............-131.3 dBc/Hz
•
•
•
•
Full 3.3V supply mode
0°C to 70°C ambient operating temperature
Available in lead-free (RoHS 6) package
Industrial temperature information available upon request
Table 1. Frequency Table - Typical Applications
Inputs
Crystal Frequency (MHz)
25
26.6
Output Frequency Range (MHz)
125
133
Block Diagram
25MHz
Pin Assignment
Phase
Detector
VCO
÷5
Q0
nQ0
V
CCA
V
EE
XTAL_OUT
XTAL_IN
1
2
3
4
8
7
6
5
V
CC
Q0
nQ0
nc
XTAL_IN
OSC
XTAL_OUT
÷25
(fixed)
843021
8 Lead TSSOP
4.40mm x 3.0mm x 0.925 package body
G Package
Top View
843021 REVISION D 9/25/15
1
©2015 Integrated Device Technology, Inc.
843021 DATA SHEET
Table 2. Pin Descriptions
Number
1
2
3,
4
5
6, 7
8
Name
V
CCA
V
EE
XTAL_OUT
XTAL_IN
nc
nQ0, Q0
V
CC
Unused
Power
Input
Unused
Output
Power
Type
Description
Analog supply pin.
Negative supply pin.
Crystal oscillator interface. XTAL_IN is the input, XTAL_OUT is the output.
No connect.
Differential output pair. LVPECL interface levels.
Core supply pin.
Table 3. Pin Characteristics
Symbol
C
IN
Parameter
Input Capacitance
Test Conditions
Minimum
Typical
4
Maximum
Units
pF
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
Continuos Current
Surge Current
Package Thermal Impedance,
JA
Storage Temperature, T
STG
Rating
4.6V
-0.5V to V
CC
+ 0.5V
50mA
100mA
101.7C/W (0 mps)
-65C to 150C
DC Electrical Characteristics
Table 4A. Power Supply DC Characteristics,
V
CC
= 3.3V ± 10%, V
EE
= 0V, T
A
= 0°C to 70°C
Symbol
V
CC
V
CCA
I
EE
Parameter
Core Supply Voltage
Analog Supply Voltage
Power Supply Current
Test Conditions
Minimum
2.97
2.97
Typical
3.3
3.3
Maximum
3.63
3.63
85
Units
V
V
mA
FEMTOCLOCK® CRYSTAL-TO-3.3V LVPECL CLOCK GENERATOR
2
Rev D 9/25/15
843021 DATA SHEET
Table 4B. LVPECL DC Characteristics,
V
CC
= 3.3V ±10%, V
EE
= 0V, T
A
= 0°C to 70°C
Symbol
V
OH
V
OL
V
SWING
Parameter
Output High Voltage; NOTE 1
Output Low Voltage; 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
V
V
V
NOTE 1: Outputs termination with 50 to V
CC
– 2V.
Table 5. Crystal Characteristics
Parameter
Mode of Oscillation
Frequency; NOTE 1
Equivalent Series Resistance (ESR)
Shunt Capacitance
NOTE 1:Input frequency is limited to a range of 22.4MHz – 28MHz due to VCO range.
14
Test Conditions
Minimum
Typical
Fundamental
40
50
7
MHz
Maximum
Units
pF
AC Electrical Characteristics
Table 6. AC Characteristics,
V
CC
= 3.3V ± 10%, V
EE
= 0V, T
A
= 0°C to 70°
Symbol
f
OUT
tjit(Ø)
t
R
/ t
F
odc
Parameter
Output Frequency
RMS Phase Jitter, Random;
NOTE 1
Output Rise/Fall Time
Output Duty Cycle
125MHz,
Integration Range: 1.875MHz – 20MHz
20% to 80%
250
49
Test Conditions
Minimum
112
0.37
Typical
Maximum
140
0.65
550
51
Units
MHz
ps
ps
%
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: Refer to Phase Noise Plot.
FEMTOCLOCK® CRYSTAL-TO-3.3V LVPECL CLOCK GENERATOR
3
Rev D 9/25/15
843021 DATA SHEET
Typical Phase Noise at 125MHz
0
-10
-20
-30
-40
-50
-60
dBc
Hz
-70
-80
-90
-100
-110
-120
-130
-140
125MHz
RMS Phase Jitter (Random)
1.875MHz to 20MHz = 0.37ps (typical)
Noise Power
Raw Phase Noise Data
-160
-170
-180
-190
100
1k
10k
100k
➝
-150
Phase Noise Result by adding a
10Gb Ethernet filter to raw data
1M
➝
10Gb Ethernet Filter
Offset Frequency (Hz)
➝
4
10M
100M
FEMTOCLOCK® CRYSTAL-TO-3.3V LVPECL CLOCK GENERATOR
Rev D 9/25/15
843021 DATA SHEET
Parameter Measurement Information
2V
Phase Noise Plot
Noise Power
V
CC,
V
CCA
Q
SCOPE
Phase Noise Mask
LVPECL
nQ
V
EE
f
1
Offset Frequency
f
2
RMS Jitter = Area Under the Masked Phase Noise Plot
-1.3V±0.33V
3.3V LVPECL Output Load AC Test Circuit
RMS Phase Jitter
nQ0
nQ0
Q0
Q0
Output Duty Cycle/Pulse Width/Period
Output Rise/Fall Time
FEMTOCLOCK® CRYSTAL-TO-3.3V LVPECL CLOCK GENERATOR
5
Rev D 9/25/15
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