FemtoClock
®
Crystal-to-3.3V, 2.5V
LVPECL Clock Generator
843251I-15
DATA SHEET
General Description
The 843251I-15 is an Ethernet Clock Generator. The 843251I-15
uses an 18pF parallel resonant crystal over the range of 23.2MHz -
30MHz. For Ethernet applications, a 25MHz crystal is used. The
843251I-15 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-15 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 pair
Crystal oscillator interface, 18pF parallel resonant crystal
(23.2MHz – 30MHz)
Output frequency range: 116MHz – 150MHz and
580MHz – 750MHz
VCO range: 580MHz – 750MHz
RMS phase jitter @ 125MHz, using a 25MHz crystal
(1.875MHz – 20MHz): 0.45ps (typical), 3.3V
Full 3.3V or 2.5V supply modes
-40°C to 85°C ambient operating temperature
Available in lead-free (RoHS 6) package
Common Configuration Table
Inputs
Crystal Frequency (MHz)
25
26.667
25
26.667
FREQ_SEL
1
1
0
0
M
25
25
25
25
N
1
1
5
5
Multiplication Value
M/N
25
25
5
5
Output Frequency (MHz)
625
666.67
125
133.33
Block Diagram
FREQ_SEL
Pulldown
Pin Assignment
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
M = ÷25
(fixed)
843251I-15
8 Lead TSSOP
4.40mm x 3.0mm x 0.925mm
package body
G Package
Top View
843251I-15 REVISION B 10/29/15
1
©2015 Integrated Device Technology, Inc.
843251I-15 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
Power
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
®
CRYSTAL-TO-3.3V, 2.5V LVPECL CLOCK GENERATOR
2
REVISION B 10/29/15
843251I-15 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
Item
Supply Voltage, V
CC
Inputs, V
I
Outputs, I
O
Continuous Current
Surge Current
Package Thermal Impedance,
JA
Storage Temperature, T
STG
in the
DC Characteristics or AC Characteristics
is not implied.
Exposure to absolute maximum rating conditions for extended
periods may affect product reliability.
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
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
Table 3B. Power Supply DC Characteristics,
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
Table 3C. LVCMOS/LVTTL DC Characteristics,
V
CC
= 3.3V ± 5% or 2.5V ± 5%, V
EE
= 0V, T
A
= -40°C to 85°C
Symbol
V
IH
Parameter
Input High Voltage
Test Conditions
V
CC
= 3.3V
V
CC
= 2.5V
Input Low Voltage
Input High Current
Input Low Current
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
V
IL
I
IH
I
IL
REVISION B 10/29/15
3
FEMTOCLOCK
®
CRYSTAL-TO-3.3V, 2.5V LVPECL CLOCK GENERATOR
843251I-15 DATA SHEET
Table 3D. 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
V
V
V
NOTE 1: Outputs termination with 50 to V
CC
– 2V.
Table 3E. LVPECL DC Characteristics,
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 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
0.4
Typical
Maximum
V
CC
– 0.9
V
CC
– 1.5
1.0
Units
V
V
V
NOTE 1: Outputs termination with 50 to V
CC
– 2V.
Table 4. Crystal Characteristics
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
Maximum
Units
pF
FEMTOCLOCK
®
CRYSTAL-TO-3.3V, 2.5V LVPECL CLOCK GENERATOR
4
REVISION B 10/29/15
843251I-15 DATA SHEET
AC Electrical Characteristics
Table 5A. AC Characteristics,
V
CC
= 3.3V ± 5%, V
EE
= 0V, T
A
= -40°C to 85°C
Symbol
f
OUT
Parameter
Output Frequency
Test Conditions
FREQ_SEL = 0
FREQ_SEL = 1
125MHz,
(Integration Range: 1.875MHz – 20MHz)
625MHz,
(Integration Range: 1.875MHz – 20MHz)
20% to 80%
100
47
Minimum
116
580
0.45
0.34
600
53
Typical
Maximum
150
750
Units
MHz
MHz
ps
ps
ps
%
tjit(Ø)
RMS Phase Jitter, Random;
NOTE 1
Output Rise/Fall Time
Output Duty Cycle
t
R
/ t
F
odc
NOTE 1: Refer to Phase Noise Plots.
Table 5B. AC Characteristics,
V
CC
= 2.5V ± 5%, V
EE
= 0V, T
A
= -40°C to 85°C
Symbol
f
OUT
Parameter
Output Frequency
Test Conditions
FREQ_SEL = 0
FREQ_SEL = 1
125MHz,
(Integration Range: 1.875MHz – 20MHz)
625MHz,
(Integration Range: 1.875MHz – 20MHz)
20% to 80%
100
45
Minimum
116
580
0.44
0.33
600
55
Typical
Maximum
150
750
Units
MHz
MHz
ps
ps
ps
%
tjit(Ø)
RMS Phase Jitter, Random;
NOTE 1
Output Rise/Fall Time
Output Duty Cycle
t
R
/ t
F
odc
NOTE 1: Refer to Phase Noise Plots.
REVISION B 10/29/15
5
FEMTOCLOCK
®
CRYSTAL-TO-3.3V, 2.5V LVPECL CLOCK GENERATOR
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