ICST ICS844251I-15 Femtoclocksâ ¢ crystal-to-lvds clock generator Datasheet

PRELIMINARY
Integrated
Circuit
Systems, Inc.
ICS844251I-15
FEMTOCLOCKS™ CRYSTAL-TO-LVDS
CLOCK GENERATOR
GENERAL DESCRIPTION
FEATURES
The ICS844251I-15 is an Ethernet Clock
Generator and a member of the HiPerClocksTM
HiPerClockS™ family of high performance devices from ICS.
The ICS844251I-15 uses an 18pF parallel
resonant crystal over the range of 23.2MHz 30MHz. For Ethernet applications, a 25MHz crystal is
used. The device has excellent <1ps phase jitter
performance, over the 1.875MHz - 20MHz integration
range. The ICS844251I-15 is packaged in a small 8-pin
TSSOP, making it ideal for use in systems with limited
board space.
• One Differential LVDS output
ICS
• Crystal oscillator interface, 18pF parallel resonant crystal
(23.2MHz - 30MHz)
• Output frequency ranges: 116MHz - 150MHz and
580MHz - 750MHz
• VCO range: 580MHz - 750MHz
• RMS phase jitter @ 125MHz, using a 25MHz crystal
(1.875MHz - 20MHz): 0.46ps (typical)
• 3.3V or 2.5V operating supply
• -40°C to 85°C ambient operating temperature
• Available in both standard and lead-free RoHS-compliant
packages
COMMON CONFIGURATION TABLE
Inputs
Crystal Frequency (MHz)
25
N
1
Multiplication Value
M/N
25
Output Frequency
(MHz)
625
25
1
25
666.67
25
5
5
125
25
5
5
133.33
FREQ_SEL
1
M
25
26.667
1
25
0
26.667
0
BLOCK DIAGRAM
FREQ_SEL
Pulldown
XTAL_IN
OSC
XTAL_OUT
PIN ASSIGNMENT
Phase
Detector
VCO
580MHz - 750MHz
FREQ_SEL N
0
÷1
1
÷5
Q
nQ
VDDA
GND
XTAL_OUT
XTAL_IN
1
2
3
4
8
7
6
5
VDD
Q
nQ
FREQ_SEL
ICS844251I-15
8-Lead TSSOP
4.4mm x 3.0mm x 0.925mm
package body
G Package
Top View
M = ÷25 (fixed)
The Preliminary Information presented herein represents a product in prototyping or pre-production. The noted characteristics are based on
initial product characterization. Integrated Circuit Systems, Incorporated (ICS) reserves the right to change any circuitry or specifications
without notice.
844251BGI-15
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1
REV. A NOVEMBER 23, 2005
PRELIMINARY
ICS844251I-15
FEMTOCLOCKS™ CRYSTAL-TO-LVDS
CLOCK GENERATOR
Integrated
Circuit
Systems, Inc.
TABLE 1. PIN DESCRIPTIONS
Number
Name
Type
Description
1
VDDA
Power
2
Power
5
GND
XTAL_OUT,
XTAL_IN
FREQ_SEL
6, 7
nQ, Q
Output
Differential clock outputs. LVDS interface levels.
8
VDD
Power
Power supply pin.
3, 4
Input
Input
Analog supply pin.
Power supply ground.
Crystal oscillator interface. XTAL_IN is the input,
XTAL_OUT is the output.
Pulldown Frequency select pin. LVCMOS/LVTTL interface levels.
NOTE: Pullup refers to internal input resistors. See Table 2, Pin Characteristics, for typical values.
TABLE 2. PIN CHARACTERISTICS
Symbol
Parameter
CIN
Input Capacitance
4
pF
RPULLDOWN
Input Pulldown Resistor
51
kΩ
844251BGI-15
Test Conditions
Minimum
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2
Typical
Maximum
Units
REV. A NOVEMBER 23, 2005
PRELIMINARY
Integrated
Circuit
Systems, Inc.
ICS844251I-15
FEMTOCLOCKS™ CRYSTAL-TO-LVDS
CLOCK GENERATOR
ABSOLUTE MAXIMUM RATINGS
Supply Voltage, VDD
4.6V
Inputs, VI
-0.5V to VDD + 0.5 V
Outputs, IO (LVDS)
Continuous Current
Surge Current
10mA
15mA
Package Thermal Impedance, θJA
101.7°C/W (0 mps)
Storage Temperature, TSTG
-65°C to 150°C
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.
TABLE 3A. POWER SUPPLY DC CHARACTERISTICS, VDD = VDDA = 3.3V±5%, TA = -40°C TO 85°C
Symbol
Parameter
Minimum
Typical
Maximum
Units
VDD
Power Supply Voltage
Test Conditions
3.135
3.3
3.465
V
VDDA
Analog Supply Voltage
3.135
3.3
3.465
V
IDD
Power Supply Current
100
mA
IDDA
Analog Supply Current
8
mA
TABLE 3B. POWER SUPPLY DC CHARACTERISTICS, VDD = VDDA = 2.5V±5%, TA = -40°C TO 85°C
Symbol
Parameter
Minimum
Typical
Maximum
Units
VDD
Power Supply Voltage
Test Conditions
2.375
2.5
2.625
V
2.375
2.5
2.625
VDDA
Analog Supply Voltage
IDD
Power Supply Current
95
mA
IDDA
Analog Supply Current
8
mA
V
TABLE 3C. LVCMOS/LVTTL DC CHARACTERISTICS, VDD = VDDA = 3.3V±5% OR 2.5V±5%, TA = -40°C TO 85°C
Symbol
Parameter
VIH
Input High Voltage
VIL
Input Low Voltage
IIH
Input High Current
VDD = VIN = 3.465V or 2.625V
IIL
Input Low Current
VDD = 3.465V or 2.625V, VIN = 0V
844251BGI-15
Test Conditions
Minimum
Typical
Maximum
Units
VDD = 3.3V
2
VDD + 0.3
V
VDD = 2.5V
1.7
VDD + 0.3
V
VDD = 3.3V
-0.3
0.8
V
VDD = 2.5V
-0.3
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3
-5
0.7
V
150
µA
µA
REV. A NOVEMBER 23, 2005
PRELIMINARY
ICS844251I-15
FEMTOCLOCKS™ CRYSTAL-TO-LVDS
CLOCK GENERATOR
Integrated
Circuit
Systems, Inc.
TABLE 3D. LVDS DC CHARACTERISTICS, VDD = VDDA = 3.3V±5%, TA = -40°C TO 85°C
Symbol
Parameter
Test Conditions
Minimum
Typical
Maximum
Units
VOD
Differential Output Voltage
400
mV
Δ VOD
VOD Magnitude Change
TBD
mV
VOS
Offset Voltage
Δ VOS
VOS Magnitude Change
1.4
V
TBD
mV
TABLE 3E. LVDS DC CHARACTERISTICS, VDD = VDDA = 2.5V±5%, TA = -40°C TO 85°C
Symbol
Parameter
VOD
Differential Output Voltage
Test Conditions
Minimum
Typical
400
Maximum
Units
mV
Δ VOD
VOD Magnitude Change
TBD
mV
VOS
Offset Voltage
1.15
V
Δ VOS
VOS Magnitude Change
TBD
mV
TABLE 4. CRYSTAL CHARACTERISTICS
Parameter
Test Conditions
Minimum
Mode of Oscillation
Typical
Maximum
Units
30
MHz
Fundamental
Frequency
23.2
Equivalent Series Resistance (ESR)
50
Ω
Shunt Capacitance
7
pF
Drive Level
1
mW
TABLE 5A. AC CHARACTERISTICS, VDD = VDDA = 3.3V±5%, TA = -40°C TO 85°C
Symbol
Parameter
fOUT
Output Frequency
t jit(Ø)
RMS Phase Jitter ( Random);
NOTE 1
t R / tF
Output Rise/Fall Time
Test Conditions
Minimum
Maximum
Units
f_SEL = 0
11 6
150
MHz
f_SEL = 1
125MHz @ Integration Range:
1.875MHz - 20MHz
625MHz @ Integration Range:
1.875MHz - 20MHz
20% to 80%
580
750
MHz
odc
Output Duty Cycle
NOTE 1: Please refer to the Phase Noise Plots following this section.
Typical
0.46
ps
0.35
ps
300
ps
50
%
TABLE 5B. AC CHARACTERISTICS, VDD = VDDA = 2.5V±5%, TA = -40°C TO 85°C
Symbol
Parameter
fOUT
Output Frequency
tjit(Ø)
RMS Phase Jitter ( Random);
NOTE 1
t R / tF
Output Rise/Fall Time
Test Conditions
Minimum
Maximum
Units
f_SEL = 0
11 6
150
MHz
f_SEL = 1
125MHz @ Integration Range:
1.875MHz - 20MHz
625MHz @ Integration Range:
1.875MHz - 20MHz
20% to 80%
580
750
MHz
odc
Output Duty Cycle
NOTE 1: Please refer to the Phase Noise Plots following this section.
844251BGI-15
Typical
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4
0.46
ps
0.35
ps
300
ps
50
%
REV. A NOVEMBER 23, 2005
PRELIMINARY
Integrated
Circuit
Systems, Inc.
ICS844251I-15
FEMTOCLOCKS™ CRYSTAL-TO-LVDS
CLOCK GENERATOR
TYPICAL PHASE NOISE
AT
125MHZ @ 3.3V
0
➤
-10
Ethernet Filter
-20
-40
125MHz
-50
RMS Phase Jitter (Random)
1.875MHz to 20MHz = 0.46ps (typical)
-60
-70
-80
-90
Raw Phase Noise Data
-100
-110
➤
NOISE POWER dBc
Hz
-30
-120
-130
-140
-150
➤
-160
-170
-180
-190
100
1k
10k
Phase Noise Result by adding
Ethernet Filter to raw data
100k
1M
10M
100M
OFFSET FREQUENCY (HZ)
TYPICAL PHASE NOISE
AT
625MHZ @ 3.3V
➤
0
-10
Ethernet Filter
-20
-40
625MHz
-50
RMS Phase Jitter (Random)
1.875MHz to 20MHz = 0.35ps (typical)
-60
-70
-80
Raw Phase Noise Data
-90
-100
➤
NOISE POWER dBc
Hz
-30
-110
-120
-130
-140
-150
-160
➤
-170
-180
Phase Noise Result by adding
Ethernet Filter to raw data
-190
100
1k
10k
100k
1M
10M
100M
OFFSET FREQUENCY (HZ)
844251BGI-15
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REV. A NOVEMBER 23, 2005
PRELIMINARY
ICS844251I-15
FEMTOCLOCKS™ CRYSTAL-TO-LVDS
CLOCK GENERATOR
Integrated
Circuit
Systems, Inc.
PARAMETER MEASUREMENT INFORMATION
SCOPE
Qx
3.3V±5%
POWER SUPPLY
Qx
2.5V±5%
POWER SUPPLY
LVDS
+ Float GND -
+ Float GND -
SCOPE
LVDS
nQx
nQx
LVDS 3.3V OUTPUT LOAD AC TEST CIRCUIT
LVDS 2.5V OUTPUT LOAD AC TEST CIRCUIT
nQ
80%
80%
Q
VSW I N G
Clock
Outputs
t PW
20%
20%
t
tF
tR
odc =
PERIOD
t PW
x 100%
t PERIOD
OUTPUT RISE/FALL TIME
OUTPUT DUTY CYCLE/PULSE WIDTH/PERIOD
Phase Noise Plot
Noise Power
VDD
V
DD
out
LVDS
➤
DC Input
Phase Noise Mask
➤
out
Offset Frequency
f2
➤
f1
VOS/Δ VOS
RMS Jitter = Area Under the Masked Phase Noise Plot
OFFSET VOLTAGE SETUP
RMS PHASE JITTER
VDD
V
DD
➤
out
➤
LVDS
100
VOD/Δ VOD
out
➤
DC Input
DIFFERENTIAL OUTPUT VOLTAGE SETUP
844251BGI-15
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REV. A NOVEMBER 23, 2005
PRELIMINARY
Integrated
Circuit
Systems, Inc.
ICS844251I-15
FEMTOCLOCKS™ CRYSTAL-TO-LVDS
CLOCK GENERATOR
APPLICATION INFORMATION
POWER SUPPLY FILTERING TECHNIQUES
As in any high speed analog circuitry, the power supply pins
are vulnerable to random noise. The ICS844251I-15 provides
separate power supplies to isolate any high switching
noise from the outputs to the internal PLL. VDD and VDDA should
be individually connected to the power supply
plane through vias, and bypass capacitors should be
used for each pin. To achieve optimum jitter performance,
power supply isolation is required. Figure 1 illustrates how
a 10Ω resistor along with a 10μF and a .01μF bypass
capacitor should be connected to each VDDA pin. The 10Ω
resistor can also be replaced by a ferrite bead.
3.3V or 2.5V
VDD
.01μF
10 Ω
VDDA
.01μF
10μF
FIGURE 1. POWER SUPPLY FILTERING
CRYSTAL INPUT INTERFACE
The ICS844251I-15 has been characterized with 18pF parallel
resonant crystals. The capacitor values, C1 and C2, shown in
Figure 2 below were determined using a 25MHz, 18pF parallel
resonant crystal and were chosen to minimize the ppm error.
The optimum C1 and C2 values can be slightly adjusted for different board layouts.
XTAL_IN
C1
X1
Crystal
XTAL_OUT
C2
Figure 2. CRYSTAL INPUt INTERFACE
844251BGI-15
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REV. A NOVEMBER 23, 2005
PRELIMINARY
ICS844251I-15
FEMTOCLOCKS™ CRYSTAL-TO-LVDS
CLOCK GENERATOR
Integrated
Circuit
Systems, Inc.
3.3V, 2.5V LVDS DRIVER TERMINATION
A general LVDS interface is shown in Figure 3. In a 100Ω
differential transmission line environment, LVDS drivers
require a matched load termination of 100Ω across near
the receiver input.
2.5V or 3.3V
VDD
LVDS_Driv er
+
R1
100
-
100 Ohm Differential Transmission Line
FIGURE 3. TYPICAL LVDS DRIVER TERMINATION
844251BGI-15
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REV. A NOVEMBER 23, 2005
PRELIMINARY
Integrated
Circuit
Systems, Inc.
ICS844251I-15
FEMTOCLOCKS™ CRYSTAL-TO-LVDS
CLOCK GENERATOR
RELIABILITY INFORMATION
TABLE 6. θJAVS. AIR FLOW TABLE
FOR
8 LEAD TSSOP
θJA by Velocity (Meters per Second)
Multi-Layer PCB, JEDEC Standard Test Boards
0
1
2.5
101.7°C/W
90.5°C/W
89.8°C/W
TRANSISTOR COUNT
The transistor count for ICS844251I-15 is: 2398
844251BGI-15
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9
REV. A NOVEMBER 23, 2005
PRELIMINARY
ICS844251I-15
FEMTOCLOCKS™ CRYSTAL-TO-LVDS
CLOCK GENERATOR
Integrated
Circuit
Systems, Inc.
PACKAGE OUTLINE - G SUFFIX
FOR
8 LEAD TSSOP
TABLE 7. PACKAGE DIMENSIONS
SYMBOL
Millimeters
Minimum
N
Maximum
8
A
--
1.20
A1
0.05
0.15
A2
0.80
1.05
b
0.19
0.30
c
0.09
0.20
D
2.90
E
E1
3.10
6.40 BASIC
4.30
e
4.50
0.65 BASIC
L
0.45
0.75
α
0°
8°
aaa
--
0.10
Reference Document: JEDEC Publication 95, MO-153
844251BGI-15
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10
REV. A NOVEMBER 23, 2005
PRELIMINARY
Integrated
Circuit
Systems, Inc.
ICS844251I-15
FEMTOCLOCKS™ CRYSTAL-TO-LVDS
CLOCK GENERATOR
TABLE 8. ORDERING INFORMATION
Part/Order Number
Marking
Package
Shipping Packaging
Temperature
ICS844251BGI-15
4BI15
8 Lead TSSOP
tube
-40°C to 85°C
ICS844251BGI-15T
4BI15
8 Lead TSSOP
2500 tape & reel
-40°C to 85°C
ICS844251BGI-15LF
TB D
8 Lead "Lead-Free" TSSOP
tube
-40°C to 85°C
ICS844251BGI-15LFT
TBD
8 Lead "Lead-Free" TSSOP
2500 tape & reel
-40°C to 85°C
NOTE: Par ts thar are ordered with an "LF" suffix to the par t number are the Pb-Free configuraiton and are RoHS compliant.
The aforementioned trademarks, HiPerClockS and FemtoClocks are trademarks of Integrated Circuit Systems, Inc. or its subsidiaries in the United States and/or other countries.
While the information presented herein has been checked for both accuracy and reliability, Integrated Circuit Systems, Incorporated (ICS) assumes no responsibility for either its use
or for infringement of any patents or other rights of third parties, which would result from its use. No other circuits, patents, or licenses are implied. This product is intended for use
in normal commercial and industrial applications. Any other applications such as those requiring high reliability or other extraordinary environmental requirements are not
recommended without additional processing by ICS. ICS reserves the right to change any circuitry or specifications without notice. ICS does not authorize or warrant any ICS product
for use in life support devices or critical medical instruments.
844251BGI-15
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11
REV. A NOVEMBER 23, 2005
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