Femtoclock
®
Crystal-to-3.3V,
2.5V LVPECL Clock Generator
843251I-12
Data Sheet
G
ENERAL
D
ESCRIPTION
The 843251I-12 is a 10Gb Ethernet Clock Generator. The 843251I-
12 uses an 18pF parallel resonant crystal over the range of 23.2MHz
- 30MHz. For Ethernet applications, a 25MHz crystal is used.
The 843251I-12 uses IDT’s 3
rd
generation low phase noise VCO
technology, and can achieve <1ps rms phase jitter performance
over the 1.875MHz - 20MHz integration range. The 843251I-12 is
packaged in a small 8-pin TSSOP, making it ideal for use in systems
with limited board space.
F
EATURES
•
One Differential LVPECL output
•
Crystal oscillator interface, 18pF parallel resonant crystal
(23.2MHz - 30MHz)
•
Output frequency range: 290MHz - 750MHz
•
VCO range: 580MHz - 750MHz
•
RMS phase jitter @ 312.5MHz, using a 25MHz crystal
(1.875MHz - 20MHz): 0.36ps (typical)
•
3.3V or 2.5V operating supply
•
-40°C to 85°C ambient operating temperature
•
Available in lead-free (RoHS 6) package
C
OMMON
C
ONFIGURATION
T
ABLE
Inputs
Crystal Frequency
(MHz)
25
25
FREQ_SEL
1
0
M
25
25
N
1
2
Multiplication Value
M/N
25
12.5
Output Frequency
(MHz)
625
312.5
B
LOCK
D
IAGRAM
FREQ_SEL
Pulldown
P
IN
A
SSIGNMENT
V
CCA
V
EE
XTAL_OUT
XTAL_IN
1
2
3
4
8
7
6
5
V
CC
Q
nQ
FREQ_SEL
XTAL_IN
OSC
XTAL_OUT
Phase
Detector
VCO
580MHz - 750MHz
FREQ_SEL N
1
÷1
0
(default)
÷5
Q
nQ
843251I-12
8-Lead TSSOP
4.4mm x 3.0mm x 0.925mm package body
G Package
Top View
M = ÷25
(fixed)
©2016 Integrated Device Technology, Inc
1
Revision A January 19, 2016
843251I-12 Data Sheet
T
ABLE
1. P
IN
D
ESCRIPTIONS
Number
1
2
3, 4
5
6, 7
8
Name
V
CCA
V
EE
XTAL_OUT,
XTAL_IN
FREQ_SEL
nQ, Q
V
CC
Power
Power
Input
Input
Output
Power
Type
Description
Analog supply pin.
Negative supply pin.
Crystal oscillator interface. XTAL_IN is the input,
XTAL_OUT is the output.
Pulldown Frequency select pin. LVCMOS/LVTTL interface levels.
Differential clock outputs. LVPECL interface levels.
Core supply pin.
NOTE:
Pulldown
refers to internal input resistors. See Table 2, Pin Characteristics, for typical values.
T
ABLE
2. P
IN
C
HARACTERISTICS
Symbol
C
IN
R
PULLDOWN
Parameter
Input Capacitance
Input Pulldown Resistor
Test Conditions
Minimum
Typical
4
51
Maximum
Units
pF
kΩ
©2016 Integrated Device Technology, Inc
2
Revision A January 19, 2016
843251I-12 Data Sheet
A
BSOLUTE
M
AXIMUM
R
ATINGS
Supply Voltage, V
CC
Inputs, V
I
Outputs, I
O
Continuous Current
Surge Current
Package Thermal Impedance,
θ
JA
Storage Temperature, T
STG
4.6V
-0.5V to V
CC
+ 0.5V
50mA
100mA
129.5°C/W (0 mps)
-65°C to 150°C
N OT E : S t r e s s e s b eyo n d t h o s e l i s t e d u n d e r A b s o l u t e
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 ex-
tended periods may affect product reliability.
T
ABLE
3A. P
OWER
S
UPPLY
DC C
HARACTERISTICS
,
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
Core Supply Voltage
Analog Supply Voltage
Power Supply Current
Analog Supply Current
Test Conditions
Minimum
3.135
V
CC
– 0.10
Typical
3.3
3.3
Maximum
3.465
V
CC
83
10
Units
V
V
mA
mA
T
ABLE
3B. P
OWER
S
UPPLY
DC C
HARACTERISTICS
,
V
CC
= 2.5V±5%, V
EE
= 0V, T
A
= -40°C
TO
85°C
Symbol
V
CC
V
CCA
I
EE
I
CCA
Parameter
Core Supply Voltage
Analog Supply Voltage
Power Supply Current
Analog Supply Current
Test Conditions
Minimum
2.375
V
CC
– 0.08
Typical
2.5
2.5
Maximum
2.625
V
CC
78
8
Units
V
V
mA
mA
T
ABLE
3C. LVCMOS/LVTTL DC C
HARACTERISTICS
,
V
CC
= 3.3V±5%
OR
2.5V±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
Test Conditions
V
CC
= 3.3V
V
CC
= 2.5V
V
CC
= 3.3V
V
CC
= 2.5V
V
CC
= V
IN
= 3.465V or 2.625V
V
CC
= 3.465V or 2.625V, V
IN
= 0V
-5
Minimum
2
1.7
-0.3
-0.3
Typical
Maximum
V
CC
+ 0.3
V
CC
+ 0.3
0.8
0.7
150
Units
V
V
V
V
µA
µA
©2016 Integrated Device Technology, Inc
3
Revision A January 19, 2016
843251I-12 Data Sheet
T
ABLE
3D. LVPECL DC C
HARACTERISTICS
,
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 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 terminated with 50Ω to V
CC
- 2V.
T
ABLE
3E. LVPECL DC C
HARACTERISTICS
,
V
CC
= 2.5V±5%, V
EE
= 0V, T
A
= -40°C
TO
85°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
0.4
Typical
Maximum
V
CC
- 0.9
V
CC
- 1.5
1.0
Units
V
V
V
NOTE 1: Outputs terminated with 50Ω to V
CC
- 2V.
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.
23.2
Test Conditions
Minimum
Typical
Fundamental
30
40
7
MHz
Ω
pF
Maximum
Units
T
ABLE
5A. AC C
HARACTERISTICS
,
V
CC
= 3.3V±5%, V
EE
= 0V, T
A
= -40°C
TO
85°C
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
Test Conditions
FREQ_SEL = 0
FREQ_SEL = 1
312.5MHz @ Integration Range:
1.875MHz - 20MHz
20% to 80%
100
47
Minimum
Typical
312.5
625
0.36
600
53
Maximum
Units
MHz
MHz
ps
ps
%
NOTE 1: Refer to the Phase Noise Plots following this section.
T
ABLE
5B. AC C
HARACTERISTICS
,
V
CC
= 2.5V±5%, V
EE
= 0V, T
A
= -40°C
TO
85°C
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
Test Conditions
FREQ_SEL = 0
FREQ_SEL = 1
312.5MHz @ Integration Range:
1.875MHz - 20MHz
20% to 80%
100
45
Minimum
Typical
312.5
625
0.38
600
55
Maximum
Units
MHz
MHz
ps
ps
%
NOTE 1: Refer to the Phase Noise Plots following this section.
©2016 Integrated Device Technology, Inc
4
Revision A January 19, 2016
843251I-12 Data Sheet
T
YPICAL
P
HASE
N
OISE AT
312.5MH
Z
(3.3V)
0
-10
-20
-30
-40
-50
-60
-70
-80
10GigE Filter
312.5MHz
RMS Phase Jitter (Random)
1.875Mhz to 20MHz = 0.36ps (typical)
N
OISE
P
OWER
dBc
Hz
-90
-100
-110
-120
-130
-140
-150
-160
-170
-180
-190
100
1k
Raw Phase Noise Data
Phase Noise Result by adding
10GigE Filter to raw data
10k
100k
1M
10M
100M
O
FFSET
F
REQUENCY
©2016 Integrated Device Technology, Inc
5
Revision A January 19, 2016
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