ICS ICS843023

PRELIMINARY
Integrated
Circuit
Systems, Inc.
ICS843023
FEMTOCLOCKS™ CRYSTAL-TO3.3V, 250MHZ LVPECL CLOCK GENERATOR
GENERAL DESCRIPTION
FEATURES
The ICS843023 is a Gigabit Ethernet Clock
Generator and a member of the HiPerClocksTM
HiPerClockS™
family of high performance devices from ICS. The
ICS843023 uses a 25MHz crystal to synthesize
250MHz. The ICS843023 has excellent phase jitter
performance, over the 1.875MHz – 20MHz integration range.
The ICS843023 is packaged in a small 8-pin TSSOP, making it
ideal for use in systems with limited board space.
• 1 differential 3.3V LVPECL output
ICS
• Crystal oscillator interface designed for 25MHz,
18pF parallel resonant crystal
• Maximum output frequency: 250MHz, using a 25MHz crystal
• VCO range: 490MHz - 640MHz
• RMS phase jitter @ 250MHz, using a 25MHz crystal
(12KHz - 20MHz): 0.33ps (typical)
• 3.3V operating supply
• 0°C to 70°C ambient operating temperature
BLOCK DIAGRAM
PIN ASSIGNMENT
OE
25MHz
XTAL_IN
OSC
XTAL_OUT
Phase
Detector
VCO
Q0
÷2
(fixed)
VCC
XTAL_OUT
XTAL_IN
VEE
1
2
3
4
8
7
6
5
Q0
nQ0
VCC
OE
nQ0
ICS843023
8-Lead TSSOP
4.40mm x 3.0mm x 0.925mm package body
G Package
Top View
÷20
(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.
843023AG
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REV. A NOVEMBER 30, 2004
1
PRELIMINARY
Integrated
Circuit
Systems, Inc.
ICS843023
FEMTOCLOCKS™ CRYSTAL-TO3.3V, 250MHZ LVPECL CLOCK GENERATOR
TABLE 1. PIN DESCRIPTIONS
Number
Name
1, 6
Power
Core supply pin.
Input
Cr ystal oscillator interface. XTAL_IN is the input, XTAL_OUT is the output.
4
VCC
XTAL_OUT,
XTAL_IN
V EE
Power
5
OE
Input
7, 8
nQ0, Q0
Output
Negative supply pin.
Active high output enable. When logic HIGH, the outputs are enabled and
active. When logic LOW, the outputs are disabled and are in a high
impedance state. LVCMOS/LVTTL interface levels.
Differential clock outputs. LVPECL interface levels.
2, 3
Type
Description
Pullup
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
RPULLUP
Input Pullup Resistor
51
KΩ
843023AG
Test Conditions
Minimum
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2
Typical
Maximum
Units
REV. A NOVEMBER 30, 2004
PRELIMINARY
Integrated
Circuit
Systems, Inc.
ICS843023
FEMTOCLOCKS™ CRYSTAL-TO3.3V, 250MHZ LVPECL CLOCK GENERATOR
ABSOLUTE MAXIMUM RATINGS
Supply Voltage, VCC
4.6V
Inputs, VI
-0.5V to VCC + 0.5V
Outputs, IO
Continuous Current
Surge Current
50mA
100mA
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, VCC = 3.3V±5%, TA=0°C TO 70°C
Symbol
Parameter
Minimum
Typical
Maximum
Units
VCC
Core Supply Voltage
Test Conditions
3.135
3.3
3.465
V
VCCA
Analog Supply Voltage
3.135
3.3
3.465
IEE
Power Supply Current
65
V
mA
TABLE 4B. LVCMOS/LVTTL DC CHARACTERISTICS, VCC = 3.3V±5%, TA = 0°C TO 70°C
Symbol
Parameter
VIH
Input High Voltage
Test Conditions
VIL
Input Low Voltage
IIH
Input High Current
OE
VCC = VIN = 3.465V
IIL
Input Low Current
OE
VCC = 3.465V, VIN = 0V
Minimum
Maximum
Units
2
Typical
VCC + 0.3
V
-0.3
0.8
V
5
µA
-150
µA
TABLE 3C. LVPECL DC CHARACTERISTICS, VCC = 3.3V±5%, TA=0°C TO 70°C
Symbol
Parameter
Maximum
Units
VOH
Output High Voltage; NOTE 1
Test Conditions
Minimum
VCC - 1.4
Typical
VCC - 0.9
V
VOL
Output Low Voltage; NOTE 1
VCC - 2.0
VCC - 1.7
V
VSWING
Peak-to-Peak Output Voltage Swing
0.6
1.0
V
Maximum
Units
NOTE 1: Outputs terminated with 50Ω to VCC - 2V.
TABLE 4. CRYSTAL CHARACTERISTICS
Parameter
Test Conditions
Minimum
Mode of Oscillation
Typical
Fundamental
Frequency
25
MHz
Equivalent Series Resistance (ESR)
50
Ω
Shunt Capacitance
7
pF
TABLE 5. AC CHARACTERISTICS, VCC = 3.3V±5%, TA=0°C TO 70°C
Symbol
Parameter
fOUT
Output Frequency
RMS Phase Jitter (Random);
NOTE 1
Output Rise/Fall Time
tjit(Ø)
tR / tF
Test Conditions
Typical
Maximum
Units
250
MHz
Integration Range: 1.875MHz - 20MHz
0.33
ps
20% to 80%
400
ps
50
%
odc
Output Duty Cycle
NOTE 1: Please refer to the Phase Noise Plot.
843023AG
Minimum
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3
REV. A NOVEMBER 30, 2004
PRELIMINARY
Integrated
Circuit
Systems, Inc.
ICS843023
FEMTOCLOCKS™ CRYSTAL-TO3.3V, 250MHZ LVPECL CLOCK GENERATOR
PARAMETER MEASUREMENT INFORMATION
2V
Phase Noise Plot
Qx
SCOPE
Noise Power
VCC
LVPECL
Phase Noise Mask
nQx
VEE
f1
Offset Frequency
f2
-1.3V ± 0.165V
RMS Jitter = Area Under the Masked Phase Noise Plot
3.3V OUTPUT LOAD AC TEST CIRCUIT
RMS PHASE JITTER
nQ0
80%
Q0
80%
VSW I N G
Pulse Width
t
odc =
Clock
Outputs
PERIOD
20%
20%
t PW
tR
tF
t PERIOD
OUTPUT DUTY CYCLE/PULSE WIDTH/PERIOD
843023AG
OUTPUT RISE/FALL TIME
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4
REV. A NOVEMBER 30, 2004
PRELIMINARY
Integrated
Circuit
Systems, Inc.
ICS843023
FEMTOCLOCKS™ CRYSTAL-TO3.3V, 250MHZ LVPECL CLOCK GENERATOR
APPLICATION INFORMATION
CRYSTAL INPUT INTERFACE
The ICS843023 has been characterized with 18pF parallel
resonant crystals. The capacitor values, C1 and C2, shown in
Figure 1 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_OUT
C1
33p
X1
18pF Parallel Crystal
XTAL_IN
C2
27p
Figure 1. CRYSTAL INPUt INTERFACE
TERMINATION FOR 3.3V LVPECL OUTPUT
The clock layout topology shown below is a typical termination for LVPECL outputs. The two different layouts mentioned
are recommended only as guidelines.
drive 50Ω transmission lines. Matched impedance techniques
should be used to maximize operating frequency and minimize
signal distortion. Figures 2A and 2B show two different layouts
which are recommended only as guidelines. Other suitable clock
layouts may exist and it would be recommended that the board
designers simulate to guarantee compatibility across all printed
circuit and clock component process variations.
FOUT and nFOUT are low impedance follower outputs that
generate ECL/LVPECL compatible outputs. Therefore, terminating resistors (DC current path to ground) or current sources
must be used for functionality. These outputs are designed to
3.3V
Zo = 50Ω
125Ω
FOUT
FIN
Zo = 50Ω
Zo = 50Ω
FOUT
50Ω
RTT =
1
Zo
(VOH + VOL / VCC – 2) – 2
FIN
50Ω
Zo = 50Ω
VCC - 2V
RTT
84Ω
FIGURE 2A. LVPECL OUTPUT TERMINATION
843023AG
125Ω
84Ω
FIGURE 2B. LVPECL OUTPUT TERMINATION
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5
REV. A NOVEMBER 30, 2004
PRELIMINARY
Integrated
Circuit
Systems, Inc.
ICS843023
FEMTOCLOCKS™ CRYSTAL-TO3.3V, 250MHZ LVPECL CLOCK GENERATOR
POWER CONSIDERATIONS
This section provides information on power dissipation and junction temperature for the ICS843023.
Equations and example calculations are also provided.
1. Power Dissipation.
The total power dissipation for the ICS843023 is the sum of the core power plus the power dissipated in the load(s).
The following is the power dissipation for VCC = 3.3V + 5% = 3.465V, which gives worst case results.
NOTE: Please refer to Section 3 for details on calculating power dissipated in the load.
•
•
Power (core)MAX = VCC_MAX * IEE_MAX = 3.465V * 65mA= 225.2mW
Power (outputs)MAX = 30mW/Loaded Output pair
Total Power_MAX (3.465V, with all outputs switching) = 225.2mW + 30mW = 255.2mW
2. Junction Temperature.
Junction temperature, Tj, is the temperature at the junction of the bond wire and bond pad and directly affects the reliability of the
device. The maximum recommended junction temperature for HiPerClockSTM devices is 125°C.
The equation for Tj is as follows: Tj = θJA * Pd_total + TA
Tj = Junction Temperature
θJA = Junction-to-Ambient Thermal Resistance
Pd_total = Total Device Power Dissipation (example calculation is in section 1 above)
TA = Ambient Temperature
In order to calculate junction temperature, the appropriate junction-to-ambient thermal resistance θJA must be used. Assuming a
moderate air flow of 1 meter per second and a multi-layer board, the appropriate value is 90.5°C/W per Table 6 below.
Therefore, Tj for an ambient temperature of 70°C with all outputs switching is:
70°C + 0.255W * 90.5°C/W = 93.1°C. This is well below the limit of 125°C.
This calculation is only an example. Tj will obviously vary depending on the number of loaded outputs, supply voltage, air flow,
and the type of board (single layer or multi-layer).
TABLE 6. THERMAL RESISTANCE θJA
FOR
8-PIN SOIC, FORCED CONVECTION
θJA by Velocity (Meter per Second)
Multi-Layer PCB, JEDEC Standard Test Boards
843023AG
0
1
2.5
101.7°C/W
90.5°C/W
89.8°C/W
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6
REV. A NOVEMBER 30, 2004
PRELIMINARY
Integrated
Circuit
Systems, Inc.
ICS843023
FEMTOCLOCKS™ CRYSTAL-TO3.3V, 250MHZ LVPECL CLOCK GENERATOR
3. Calculations and Equations.
The purpose of this section is to derive the power dissipated into the load.
LVPECL output driver circuit and termination are shown in Figure 3.
VCC
Q1
VOUT
RL
50
VCC - 2V
FIGURE 3. LVPECL DRIVER CIRCUIT
AND
TERMINATION
To calculate worst case power dissipation into the load, use the following equations which assume a 50Ω load, and a termination
voltage of V - 2V.
CC
•
For logic high, VOUT = V
OH_MAX
(V
CCO_MAX
•
-V
OH_MAX
OL_MAX
CCO_MAX
-V
CC_MAX
– 0.9V
) = 0.9V
For logic low, VOUT = V
(V
=V
=V
CC_MAX
– 1.7V
) = 1.7V
OL_MAX
Pd_H is power dissipation when the output drives high.
Pd_L is the power dissipation when the output drives low.
Pd_H = [(V
OH_MAX
– (V
CC_MAX
- 2V))/R ] * (V
CC_MAX
L
-V
OH_MAX
) = [(2V - (V
CC_MAX
-V
OH_MAX
))/R ] * (V
CC_MAX
L
-V
OH_MAX
)=
[(2V - 0.9V)/50Ω] * 0.9V = 19.8mW
Pd_L = [(V
OL_MAX
– (V
CC_MAX
- 2V))/R ] * (V
L
CC_MAX
-V
OL_MAX
) = [(2V - (V
CC_MAX
-V
OL_MAX
))/R ] * (V
L
CC_MAX
-V
OL_MAX
)=
[(2V - 1.7V)/50Ω] * 1.7V = 10.2mW
Total Power Dissipation per output pair = Pd_H + Pd_L = 30mW
843023AG
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7
REV. A NOVEMBER 30, 2004
PRELIMINARY
Integrated
Circuit
Systems, Inc.
ICS843023
FEMTOCLOCKS™ CRYSTAL-TO3.3V, 250MHZ LVPECL CLOCK GENERATOR
RELIABILITY INFORMATION
TABLE 7. θJAVS. AIR FLOW TABLE
FOR
8 LEAD TSSOP
θJA by Velocity (Meter 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 ICS843023 is: 2360
843023AG
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8
REV. A NOVEMBER 30, 2004
PRELIMINARY
Integrated
Circuit
Systems, Inc.
PACKAGE OUTLINE - G SUFFIX
FOR
ICS843023
FEMTOCLOCKS™ CRYSTAL-TO3.3V, 250MHZ LVPECL CLOCK GENERATOR
8 LEAD TSSOP
TABLE 8. 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
843023AG
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9
REV. A NOVEMBER 30, 2004
PRELIMINARY
Integrated
Circuit
Systems, Inc.
ICS843023
FEMTOCLOCKS™ CRYSTAL-TO3.3V, 250MHZ LVPECL CLOCK GENERATOR
TABLE 9. ORDERING INFORMATION
Part/Order Number
Marking
Package
Count
Temperature
ICS843023AG
3023A
8 lead TSSOP
100 per tube
0°C to 70°C
ICS843023AGT
3023A
8 lead TSSOP on Tape and Reel
2500
0°C to 70°C
The aforementioned trademarks, HiPerClockS™
and FemtoClocks™
are a trademark 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 applications. Any other applications such as those requiring extended temperature range, 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.
843023AG
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10
REV. A NOVEMBER 30, 2004