IDT ICS8440258AK-46

PRELIMINARY
ICS8440258-46
FEMTOCLOCK™ CRYSTAL/LVCMOS-TOLVDS/LVCMOS FREQUENCY SYNTHESIZER
GENERAL DESCRIPTION
FEATURES
The ICS8440258-46 is an 8 output synthesizer
ICS
optimized to generate Ethernet clocks and a
HiPerClockS™
member of the HiPerClock S ™ family of high
performance clock solutions from IDT. Using a
25MHz, 18pF parallel resonant crystal, the device
will generate both 125MHz and 25MHz clocks with mixed
LVDS and LVCMOS/LVTTL output logic. The ICS8440258-46
uses IDT’s 3rd generations low phase noise VCO technology
and can achieve <1ps typical rms phase jitter, easily meeting
Ethernet jitter requirements. The ICS8440258-46 is packaged
in a small, 5mm x 5mm VFQFN package.
• Four differential LVDS outputs at 125MHz
Two LVCMOS/LVTTL single-ended outputs at 125MHz
Two LVCMOS/LVTTL single-ended outputs at 25MHz
• Selectable crystal oscillator interface or LVCMOS/LVTTL
single-ended input
• VCO range: 490MHz - 680MHz
• RMS phase jitter @ 125MHz, using a 25MHz crystal
(1.875MHz - 20MHz): 0.34ps (typical)
• Full 2.5V operating supply
• 0°C to 70°C ambient operating temperature
VDDA
nPLL_SEL
MR
VDD
REF_CLK
nXTAL_SEL
XTAL_IN
PIN ASSIGNMENT
XTAL_OUT
• Available in both standard (RoHS 5) and lead-free (RoHS6)
packages
32 31 30 29 28 27 26 25
Q0
1
24
nc
nQ0
2
23
nc
GND
3
22
nc
Q1
4
21
GND
nQ1
5
20
Q7
VDD
6
19
VDDO2
Q2
7
18
Q6
nQ2
8
17
GND
BLOCK DIAGRAM
ICS8440258-46
32-Lead VFQFN
5mm x 5mm x 0.925mm
package body
K Package
Top View
Q5
GND
Q4
VDDO1
VDD
GND
nQ0
Q3
Q0
nPLL_SEL Pulldown
nQ3
9 10 11 12 13 14 15 16
MR Pulldown
Q1
nQ1
25MHz
XTAL_IN
OSC
Q2
nQ2
÷5
XTAL_OUT
REF_CLK Pulldown
1
0
VCO
Phase
Detector
490-680MHz
0
Q3
nQ3
1
Q4
nXTAL_SEL Pulldown
÷25
Q5
Q6
Q7
The Preliminary Information presented herein represents a product in pre-production. The noted characteristics are based on initial product characterization
and/or qualification. Integrated Device Technology, Incorporated (IDT) reserves the right to change any circuitry or specifications without notice.
IDT ™ / ICS™ LVDS/LVCMOS FREQUENCY SYNTHESIZER
1
ICS8440258AK-46 REV B JANUARY 15, 2008
ICS8440258-46
FEMTOCLOCK™ CRYSTAL/LVCMOS-TO-LVDS/ LVCMOS FREQUENCY SYNTHESIZER
PRELIMINARY
TABLE 1. PIN DESCRIPTIONS
Number
Name
Type
Description
1, 2
3, 12, 16,
17, 21
4, 5
Q0, nQ0
Output
Differential clock outputs. LVDS interface levels.
GND
Power
Power supply ground.
Q1, nQ1
Output
Differential clock outputs. LVDS interface levels.
6, 11, 27
VDD
Power
Core supply pin.
7, 8
Q2, nQ2
Output
Differential clock outputs. LVDS interface levels.
9, 10
13, 15,
18, 20
14
Q3, nQ3
Q4, Q5,
Q6, Q7
VDDO1
Output
Differential clock outputs. LVDS interface levels.
Output
Single-ended clock outputs. LVCMOS/LVTTL interface levels.
Power
Power output supply pin for Q4 and Q5 LVCMOS outputs.
19
VDDO2
Power
Power output supply pin for Q6 and Q7 LVCMOS outputs.
22, 23, 24
nc
Unused
25
VDDA
Power
No connect.
Analog supply pin.
PLL Bypass. When LOW, the output is driven from the VCO output.
When HIGH, the PLL is bypassed and the output frequency =
26
nPLL_SEL
Input
Pulldown
reference clock frequency/N output divider.
LVCMOS/LVTTL interface levels.
Active HIGH Master Reset. When logic HIGH, the internal dividers are
28
MR
Input
Pulldown reset causing the outputs to go low. When logic LOW, the internal
dividers and the outputs are enabled. LVCMOS/LVTTL interface levels.
29
REF_CLK
Input
Pulldown Single-ended LVCMOS/LVTTL reference clock input.
Selects between the crystal or REF_CLK inputs as the PLL reference
30
nXTAL_SEL
Input
Pulldown source. When HIGH, selects REF_CLK. When LOW, selects XTAL
inputs. LVCMOS/LVTTL interface levels.
31,
XTAL_OUT,
Crystal oscillator interface. XTAL_OUT is the output.
Input
32
XTAL_IN
XTAL_IN is the input.
NOTE: Pulldown refers to internal input resistors. See Table 2, Pin Characteristics, for typical values.
TABLE 2. PIN CHARACTERISTICS
Symbol
Parameter
Test Conditions
Minimum
Typical
Maximum
Units
CIN
Input Capacitance
4
pF
CPD
Power Dissipation Capacitance
8
pF
RPULLDOWN
Input Pulldown Resistor
51
kΩ
ROUT
Output Impedance
22
Ω
IDT ™ / ICS™ LVDS/LVCMOS FREQUENCY SYNTHESIZER
2
ICS8440258AK-46 REV B JANUARY 15, 2008
ICS8440258-46
FEMTOCLOCK™ CRYSTAL/LVCMOS-TO-LVDS/ LVCMOS FREQUENCY SYNTHESIZER
PRELIMINARY
ABSOLUTE MAXIMUM RATINGS
Supply Voltage, VDD
NOTE: Stresses beyond those listed under Absolute Maximum
Ratings may cause permanent damage to the device. These
4.6V
Inputs, VI
-0.5V to VDD + 0.5V
Outputs, IO (LVCMOS)
-0.5V to VDD + 0.5V
ratings are stress specifications only. Functional operation of
product at these conditions or any conditions beyond those listed
Outputs, IO (LVDS)
Continuous Current
Surge Current
in the DC Characteristics or AC Characteristics is not implied.
Exposure to absolute maximum rating conditions for extended
10mA
15mA
periods may affect product reliability.
Operating Temperature Range, TA
-40°C to +85°C
Storage Temperature, TSTG
-65°C to 150°C
Package Thermal Impedance, θJA
37°C/W (0 mps)
TABLE 3A. POWER SUPPLY DC CHARACTERISTICS, VDD = VDDA = VDDO1 = VDDO2 = 2.5V ± 5%,TA = 0°C TO 70°C
Symbol
VDD
Parameter
Core Supply Voltage
Test Conditions
Minimum
2.375
Typical
2.5
Maximum
2.625
Units
V
VDDA
Analog Supply Voltage
VDD – 0.13
2.5
VDD
V
VDDO
Output Supply Voltage
2.375
2.5
2.625
V
IDD, IDDO1, IDDO2
Power Supply Current
170
mA
IDDA
Analog Supply Current
13
mA
TABLE 3B. LVCMOS/LVTTL DC CHARACTERISTICS, VDD = VDDA = VDDO1 = VDDO2 = 2.5V ± 5%,TA = 0°C TO 70°C
Symbol Parameter
Test Conditions
Minimum Typical
Maximum
Units
VIH
Input High Voltage
1.7
VDD + 0.3
V
VIL
Input Low Voltage
-0.3
0.7
V
IIH
Input
High Current
MR, REF_CLK,
nPLL_SEL, nXTAL_SEL
VDD = VIN = 2.625V
150
µA
IIL
Input
Low Current
MR, REF_CLK,
nPLL_SEL, nXTAL_SEL
VDD = 2.625V, VIN = 0V
-5
µA
Output
High Voltage; Q4:Q7
1.8
VDDO1, VDDO1 = 2.625V±5%
NOTE 1
Output
Low Voltage; Q4:Q7
VOL
VDDO1, VDDO1 = 2.625V±5%
NOTE 1
NOTE 1: Outputs terminated with 50Ω to VDDOX/2. See Parameter Measurement Information,
Output Load Test Circuit diagram.
VOH
IDT ™ / ICS™ LVDS/LVCMOS FREQUENCY SYNTHESIZER
3
V
0.5
V
ICS8440258AK-46 REV B JANUARY 15, 2008
ICS8440258-46
FEMTOCLOCK™ CRYSTAL/LVCMOS-TO-LVDS/ LVCMOS FREQUENCY SYNTHESIZER
PRELIMINARY
TABLE 3C. LVDS DC CHARACTERISTICS, VDD = VDDA = VDDO1 = VDDO2 = 2.5V ± 5%,TA = 0°C TO 70°C
Symbol
Parameter
Test Conditions
VOD
Differential Output Voltage
Δ VOD
VOD Magnitude Change
VOS
Offset Voltage
Δ VOS
VOS Magnitude Change
Minimum
Typical
Maximum
Units
390
mV
50
mV
1.25
V
50
mV
TABLE 4. CRYSTAL CHARACTERISTICS
Parameter
Test Conditions
Minimum
Mode of Oscillation
Typical
Maximum
Units
Fundamental
Frequency
25
MHz
Ω
Equivalent Series Resistance (ESR)
50
Shunt Capacitance
7
pF
Drive Level
1
mW
Maximum
Units
NOTE: Characterized using an 18pF parallel resonant cr ystal.
TABLE 5. AC CHARACTERISTICS, VDD = VDDA = VDDO1 = VDDO2 = 2.5V ± 5%,TA = 0°C TO 70°C
Symbol
Parameter
fOUT
Output Frequency
Test Conditions
Minimum
Typical
Q0:3/nQ0:3
125
MHz
Q4, Q5
125
MHz
Q6, Q7
25
MHz
tsk(o)
Output Skew;
NOTE 1, 2
Q0:3/nQ0:3
50
ps
Q4:Q7
50
ps
tjit(Ø)
RMS Phase Jitter
(Random); NOTE 3
Q0:3/nQ0:3
125MHz, (1.875MHz - 20MHz)
0.34
ps
Q4, Q5
125MHz, (1.875MHz - 20MHz)
0.37
ps
tR / tF
Output
Rise/Fall Time
Q0:3/nQ0:3
20% to 80%
480
ps
Q4:Q7
20% to 80%
1.4
ns
50
%
odc
Output Duty Cycle
Q0:3/nQ0:3
Q4:Q7
46
NOTE 1: Defined as skew between outputs at the same supply voltages and with equal load conditions.
Measured at VDDOX/2.
NOTE 2: This parameter is defined in accordance with JEDEC Standard 65.
NOTE 3: Please refer to the Phase Noise Plot.
IDT ™ / ICS™ LVDS/LVCMOS FREQUENCY SYNTHESIZER
4
54
%
ICS8440258AK-46 REV B JANUARY 15, 2008
ICS8440258-46
FEMTOCLOCK™ CRYSTAL/LVCMOS-TO-LVDS/ LVCMOS FREQUENCY SYNTHESIZER
PRELIMINARY
TYPICAL PHASE NOISE AT 125MHZ (LVCMOS)
➤
0
-10
-20
Ethernet Filter
-30
-40
125MHz
-60
RMS Phase Jitter (Random)
1.875MHz to 20MHz = 0.37ps (typical)
-70
-80
-90
Raw Phase Noise Data
-100
➤
NOISE POWER dBc
Hz
-50
-110
-120
-130
-140
-150
-160
➤
-170
-180
Phase Noise Result by adding
Ethernet Filter to raw data
-190
-200
10
100
1k
10k
100k
1M
10M
100M
OFFSET FREQUENCY (HZ)
TYPICAL PHASE NOISE AT 125MHZ (LVDS)
➤
0
-10
-20
Ethernet Filter
-50
125MHz
-60
RMS Phase Jitter (Random)
1.875MHz to 20MHz = 0.34ps (typical)
-70
-80
-90
-100
Raw Phase Noise Data
-110
➤
NOISE POWER dBc
Hz
-30
-40
-120
-130
-140
-150
-160
-170
➤
-180
-190
Phase Noise Result by adding
Ethernet Filter to raw data
-200
10
100
1k
10k
100k
1M
10M
100M
OFFSET FREQUENCY (HZ)
IDT ™ / ICS™ LVDS/LVCMOS FREQUENCY SYNTHESIZER
5
ICS8440258AK-46 REV B JANUARY 15, 2008
ICS8440258-46
FEMTOCLOCK™ CRYSTAL/LVCMOS-TO-LVDS/ LVCMOS FREQUENCY SYNTHESIZER
PRELIMINARY
PARAMETER MEASUREMENT INFORMATION
1.25V±5%
1.25V±5%
VDD,
VDDO1,
VDDO2
SCOPE
VDD,
VDDO1, VDDA
VDDO2
2.5V±5%
POWER SUPPLY
+ Float GND –
Qx
SCOPE
VDDA
Qx
LVCMOS
LVDS
GND
nQx
-1.25V±5%
2.5V LVDS OUTPUT LOAD AC TEST CIRCUIT
2.5V LVCMOS OUTPUT LOAD AC TEST CIRCUIT
nQx
V
DDO
Qx
Qx
2
nQy
V
DDO
Qy
Qy
2
t sk(o)
t sk(o)
LVDS OUTPUT SKEW
LVCMOS OUTPUT SKEW
80%
80%
80%
80%
VOD
Clock
Outputs
20%
20%
tR
Clock
Outputs
tF
LVDS OUTPUT RISE/FALL TIME
IDT ™ / ICS™ LVDS/LVCMOS FREQUENCY SYNTHESIZER
20%
20%
tR
tF
LVCMOS OUTPUT RISE/FALL TIME
6
ICS8440258AK-46 REV B JANUARY 15, 2008
ICS8440258-46
FEMTOCLOCK™ CRYSTAL/LVCMOS-TO-LVDS/ LVCMOS FREQUENCY SYNTHESIZER
PRELIMINARY
Phase Noise Plot
Noise Power
nQ0:nQ3
Q0:Q3
t PW
Phase Noise Mask
t
f1
Offset Frequency
odc =
f2
PERIOD
t PW
x 100%
t PERIOD
RMS Jitter = Area Under the Masked Phase Noise Plot
LVDS OUTPUT DUTY CYCLE/PULSE WIDTH/PERIOD
RMS PHASE JITTER
V
DDO
2
Q4:Q7
t PW
t
odc =
PERIOD
t PW
x 100%
t PERIOD
LVCMOS OUTPUT DUTY CYCLE/PULSE WIDTH/PERIOD
IDT ™ / ICS™ LVDS/LVCMOS FREQUENCY SYNTHESIZER
7
ICS8440258AK-46 REV B JANUARY 15, 2008
ICS8440258-46
FEMTOCLOCK™ CRYSTAL/LVCMOS-TO-LVDS/ LVCMOS FREQUENCY SYNTHESIZER
PRELIMINARY
APPLICATION INFORMATION
POWER SUPPLY FILTERING TECHNIQUES
As in any high speed analog circuitry, the power supply pins
are vulnerable to random noise. The ICS8440258-46 provides
separate power supplies to isolate any high switching noise
from the outputs to the internal PLL. VDD, VDDA, VDDO1 and VDDO2
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 0.01μF bypass capacitor should be connected to each VDDA.
2.5V
VDD
.01μF
10Ω
VDDA
.01μF
10μF
FIGURE 1. POWER SUPPLY FILTERING
CRYSTAL INPUT INTERFACE
were determined using a 25MHz, 18pF parallel resonant crystal
and were chosen to minimize the ppm error.
The ICS8440258-46 has been characterized with 18pF parallel
resonant crystals. The capacitor values shown in Figure 2 below
XTAL_IN
C1
22p
X1
18pF Parallel Cry stal
XTAL_OUT
C2
22p
ICS84332
FIGURE 2. CRYSTAL INPUt INTERFACE
IDT ™ / ICS™ LVDS/LVCMOS FREQUENCY SYNTHESIZER
8
ICS8440258AK-46 REV B JANUARY 15, 2008
ICS8440258-46
FEMTOCLOCK™ CRYSTAL/LVCMOS-TO-LVDS/ LVCMOS FREQUENCY SYNTHESIZER
PRELIMINARY
LVCMOS TO XTAL INTERFACE
(Ro) plus the series resistance (Rs) equals the transmission
line impedance. In addition, matched termination at the crystal
input will attenuate the signal in half. This can be done in one
of two ways. First, R1 and R2 in parallel should equal the
transmission line impedance. For most 50Ω applications, R1
and R2 can be 100Ω. This can also be accomplished by
removing R1 and making R2 50Ω.
The XTAL_IN input can accept a single-ended LVCMOS
signal through an AC couple capacitor. A general interface
diagram is shown in Figure 3. The XTAL_OUT pin can be left
floating. The input edge rate can be as slow as 10ns. For
LVCMOS inputs, it is recommended that the amplitude be
reduced from full swing to half swing in order to prevent signal
interference with the power rail and to reduce noise. This
configuration requires that the output impedance of the driver
VDD
VDD
R1
Ro
.1uf
Rs
Zo = 50
XTAL_IN
R2
Zo = Ro + Rs
XTAL_OUT
Figure 3. GENERAL DIAGRAM FOR LVCMOS DRIVER TO XTAL INPUT INTERFACE
RECOMMENDATIONS FOR UNUSED INPUT AND OUTPUT PINS
INPUTS:
OUTPUTS:
CRYSTAL INPUTS
For applications not requiring the use of the crystal oscillator input,
both XTAL_IN and XTAL_OUT can be left floating. Though not
required, but for additional protection, a 1kW resistor can be tied
from XTAL_IN to ground.
LVCMOS OUTPUTS
All unused LVCMOS output can be left floating. There should be
no trace attached.
LVDS OUTPUTS
All unused LVDS output pairs can be either left floating or
terminated with 100Ω across. If they are left floating, there should
be no trace attached.
REF_CLK INPUT
For applications not requiring the use of the reference clock, it
can be left floating. Though not required, but for additional
protection, a 1kΩ resistor can be tied from the REF_CLK to
ground.
LVCMOS CONTROL PINS
All control pins have internal pull-downs; additional resistance is
not required but can be added for additional protection. A 1kΩ
resistor can be used.
IDT ™ / ICS™ LVDS/LVCMOS FREQUENCY SYNTHESIZER
9
ICS8440258AK-46 REV B JANUARY 15, 2008
ICS8440258-46
FEMTOCLOCK™ CRYSTAL/LVCMOS-TO-LVDS/ LVCMOS FREQUENCY SYNTHESIZER
PRELIMINARY
2.5V LVDS DRIVER TERMINATION
Figure 4 shows a typical ter mination for LVDS driver in
characteristic impedance of 100Ω differential (50Ω single)
transmission line environment. For buffer with multiple LDVS driver,
it is recommended to terminate the unused outputs.
2.5V
2.5V
LVDS_Driv er
+
R1
100
-
100 Ohm
Differential
Transmission
Line
Ω
100Ω
Differential Transmission
Line
FIGURE 4. TYPICAL LVDS DRIVER TERMINATION
VFQFN EPAD THERMAL RELEASE PATH
are application specific and dependent upon the package power
dissipation as well as electrical conductivity requirements. Thus,
thermal and electrical analysis and/or testing are recommended
to determine the minimum number needed. Maximum thermal
and electrical performance is achieved when an array of vias is
incorporated in the land pattern. It is recommended to use as
many vias connected to ground as possible. It is also
recommended that the via diameter should be 12 to 13mils (0.30
to 0.33mm) with 1oz copper via barrel plating. This is desirable to
avoid any solder wicking inside the via during the soldering process
which may result in voids in solder between the exposed pad/
slug and the thermal land. Precautions should be taken to
eliminate any solder voids between the exposed heat slug and
the land pattern. Note: These recommendations are to be used
as a guideline only. For further information, refer to the Application
Note on the Surface Mount Assembly of Amkor’s Thermally/
Electrically Enhance Leadfame Base Package, Amkor Technology.
In order to maximize both the removal of heat from the package
and the electrical perfor mance, a land patter n must be
incorporated on the Printed Circuit Board (PCB) within the footprint
of the package corresponding to the exposed metal pad or
exposed heat slug on the package, as shown in Figure 5. The
solderable area on the PCB, as defined by the solder mask, should
be at least the same size/shape as the exposed pad/slug area on
the package to maximize the thermal/electrical performance.
Sufficient clearance should be designed on the PCB between the
outer edges of the land pattern and the inner edges of pad pattern
for the leads to avoid any shorts.
While the land pattern on the PCB provides a means of heat
transfer and electrical grounding from the package to the board
through a solder joint, thermal vias are necessary to effectively
conduct from the surface of the PCB to the ground plane(s). The
land pattern must be connected to ground through these vias.
The vias act as “heat pipes”. The number of vias (i.e. “heat pipes”)
PIN
PIN PAD
SOLDER
EXPOSED HEAT SLUG
GROUND PLANE
SOLDER
LAND PATTERN
THERMAL VIA
PIN
PIN PAD
(GROUND PAD)
FIGURE 5. P.C.ASSEMBLY FOR EXPOSED PAD THERMAL RELEASE PATH –SIDE VIEW (DRAWING NOT TO SCALE)
IDT ™ / ICS™ LVDS/LVCMOS FREQUENCY SYNTHESIZER
10
ICS8440258AK-46 REV B JANUARY 15, 2008
ICS8440258-46
FEMTOCLOCK™ CRYSTAL/LVCMOS-TO-LVDS/ LVCMOS FREQUENCY SYNTHESIZER
PRELIMINARY
POWER CONSIDERATIONS
This section provides information on power dissipation and junction temperature for the ICS8440258-46.
Equations and example calculations are also provided.
1. Power Dissipation.
The total power dissipation for the ICS840258-46 is the sum of the core power plus the power dissipated in the load(s).
The following is the power dissipation for VDD = 2.5V + 5% = 2.625V, which gives worst case results.
Core and LVDS Output Power Dissipation
•
Power (core, LVDS) = VDD_MAX * (IDD + IDDO1 + IDDO2 + IDDA ) = 2.625V * (170mA + 13mA) = 480.4mW
LVCMOS Output Power Dissipation
•
Output Impedance ROUT Power Dissipation due to Loading 50Ω to VDDO/2
Output Current IOUT = VDDO_MAX / [2 * (50Ω + ROUT)] = 2.625V / [2 * (50Ω + 12Ω)] = 21.2mA
•
Power Dissipation on the ROUT per LVCMOS output
Power (ROUT) = ROUT * (IOUT)2 = 12Ω * (21.2mA)2 = 5.4mW per output
•
Total Power Dissipation on the ROUT
Total Power (ROUT) = 5.4mW * 4 = 21.6mW
•
Dynamic Power Dissipation at 125MHz
Power (125MHz) = CPD * Frequency * (VDDO)2 = 8pF * 125MHz * (2.625V)2 = 6.9mW per output
Total Power (125MHz) = 6.9mW * 2 = 13.8mW
•
Dynamic Power Dissipation at 25MHz
Power (25MHz) = CPD * frequency * (VDDO)2 = 8pF * 25MHz * (2.625V)2 = 1.4 mW per output
Total Power (25MHz) = 1.4mW * 2 = 2.8mW
Total Power Dissipation
•
Total Power
= Power (core, LVDS) + Total Power (ROUT) + Total Power (125MHz) + Total Power (25MHz)
= 480.4mW + 21.6mW + 13.8mW + 2.8mW
= 518.6mW
IDT ™ / ICS™ LVDS/LVCMOS FREQUENCY SYNTHESIZER
11
ICS8440258AK-46 REV B JANUARY 15, 2008
ICS8440258-46
FEMTOCLOCK™ CRYSTAL/LVCMOS-TO-LVDS/ LVCMOS FREQUENCY SYNTHESIZER
PRELIMINARY
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 no air flow and a multi-layer board, the appropriate value is 37°C/W per Table 6.
Therefore, Tj for an ambient temperature of 70°C with all outputs switching is:
70°C + 0.519W * 37°C/W = 89.2°C. This is 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
32-LEAD VFQFN, FORCED CONVECTION
θJA vs. Air Flow (Meters per Second)
Multi-Layer PCB, JEDEC Standard Test Boards
IDT ™ / ICS™ LVDS/LVCMOS FREQUENCY SYNTHESIZER
0
1
2.5
37.0°C/W
32.4°C/W
29.0°C/W
12
ICS8440258AK-46 REV B JANUARY 15, 2008
ICS8440258-46
FEMTOCLOCK™ CRYSTAL/LVCMOS-TO-LVDS/ LVCMOS FREQUENCY SYNTHESIZER
PRELIMINARY
RELIABILITY INFORMATION
TABLE 7. θJAVS. AIR FLOW TABLE
FOR
32 LEAD VFQFN
θJA vs. Air Flow (Meters per Second)
Multi-Layer PCB, JEDEC Standard Test Boards
0
1
2.5
37.0°C/W
32.4°C/W
29.0°C/W
TRANSISTOR COUNT
The transistor count for ICS8440258-46 is: 2589
IDT ™ / ICS™ LVDS/LVCMOS FREQUENCY SYNTHESIZER
13
ICS8440258AK-46 REV B JANUARY 15, 2008
ICS8440258-46
FEMTOCLOCK™ CRYSTAL/LVCMOS-TO-LVDS/ LVCMOS FREQUENCY SYNTHESIZER
PRELIMINARY
PACKAGE OUTLINE - K SUFFIX FOR 32 LEAD VFQFN
NOTE: The following package mechanical drawing is a generic
drawing that applies to any pin count VFQFN package. This drawing is not intended to convey the actual pin count or pin layout of
this device. The pin count and pinout are shown on the front page.
The package dimensions are in Table 8 below.
TABLE 8. PACKAGE DIMENSIONS
JEDEC VARIATION
ALL DIMENSIONS IN MILLIMETERS
VHHD-2
SYMBOL
MINIMUM
NOMINAL
A
0.80
A1
0
--
1.00
--
0.05
0.25 Ref.
A3
b
0.18
0.25
8
NE
5.00 BASIC
D
1.25
2.25
1.25
2.25
3.25
0.50 BASIC
e
L
3.25
5.00 BASIC
E
E2
0.30
8
ND
D2
MAXIMUM
32
N
0.30
0.40
0.50
Reference Document: JEDEC Publication 95, MO-220
IDT ™ / ICS™ LVDS/LVCMOS FREQUENCY SYNTHESIZER
14
ICS8440258AK-46 REV B JANUARY 15, 2008
ICS8440258-46
FEMTOCLOCK™ CRYSTAL/LVCMOS-TO-LVDS/ LVCMOS FREQUENCY SYNTHESIZER
PRELIMINARY
TABLE 9. ORDERING INFORMATION
Part/Order Number
Marking
Package
Shipping Packaging
Temperature
ICS8440258AK-46
ICS40258A46
32 Lead VFQFN
Tray
0°C to 70°C
ICS8440258AK-46T
ICS40258A46
32 Lead VFQFN
1000 Tape & Reel
0°C to 70°C
ICS8440258AK-46LF
ICS0258A46L
32 Lead "Lead-Free" VFQFN
Tray
0°C to 70°C
ICS8440258AK-46LFT
ICS0258A46L
32 Lead "Lead-Free" VFQFN
1000 Tape & Reel
0°C to 70°C
NOTE: Par ts that are ordered with an "LF" suffix to the par t number are the Pb-Free configuration and are RoHS compliant.
While the information presented herein has been checked for both accuracy and reliability, Integrated Device Technology, Incorporated (IDT) 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 IDT. IDT
reserves the right to change any circuitry or specifications without notice. IDT does not authorize or warrant any IDT product for use in life support devices or critical medical instruments.
IDT ™ / ICS™ LVDS/LVCMOS FREQUENCY SYNTHESIZER
15
ICS8440258AK-46 REV B JANUARY 15, 2008
ICS8440258-46
FEMTOCLOCK™ CRYSTAL/LVCMOS-TO-LVDS/ LVCMOS FREQUENCY SYNTHESIZER
PRELIMINARY
Innovate with IDT and accelerate your future networks. Contact:
www.IDT.com
For Sales
For Tech Support
800-345-7015
408-284-8200
Fax: 408-284-2775
[email protected]
480-763-2056
Corporate Headquarters
Asia Pacific and Japan
Europe
Integrated Device Technology, Inc.
6024 Silver Creek Valley Road
San Jose, CA 95138
United States
800 345 7015
+408 284 8200 (outside U.S.)
Integrated Device Technology
Singapore (1997) Pte. Ltd.
Reg. No. 199707558G
435 Orchard Road
#20-03 Wisma Atria
Singapore 238877
+65 6 887 5505
IDT Europe, Limited
321 Kingston Road
Leatherhead, Surrey
KT22 7TU
England
+44 (0) 1372 363 339
Fax: +44 (0) 1372 378851
© 2008 Integrated Device Technology, Inc. All rights reserved. Product specifications subject to change without notice. IDT, the IDT logo, ICS and HiPerClockS are trademarks
of Integrated Device Technology, Inc. Accelerated Thinking is a service mark of Integrated Device Technology, Inc. All other brands, product names and marks are or may be
trademarks or registered trademarks used to identify products or services of their respective owners.
Printed in USA