Crystal-to-LVPECL Clock Synthesizer
ICS843312
DATA SHEET
General Description
Features
The ICS843312 is a high frequency clock generator. The ICS843312
uses an external 25MHz crystal to synthesize 312.5MHz and
125MHz clocks. The ICS843312 has excellent RMS period jitter
performance.
•
•
Ten differential LVPECL outputs for 312.5MHz and 125MHz
•
RMS phase jitter at 125MHz (1.875MHz - 20MHz):
0.45ps (typical)
•
RMS phase jitter at 312.5MHz (1.875MHz - 20MHz):
0.31ps (typical)
•
•
•
•
Output duty cycle: 45% – 55%, at 125MHz
The ICS843312 operates at full 3.3V and 2.5V, or mixed 3.3V/2.5V
supply modes and is available in a fully RoHS compliant 32-lead
VFQFN package.
Crystal oscillator interface designed for 18pF, 25MHz parallel
resonant crystal
Full 3.3V and 2.5V, or mixed 3.3V/2.5V supply modes
0°C to 70°C ambient operating temperature
Available in lead-free (RoHS 6) package
Output Frequency Table
Crystal Frequency (MHz)
Feedback Divider
VCO Frequency (MHz)
Output Divider
Output Frequency (MHz)
25
25
625
÷2
312.5
25
25
625
÷5
125
Block Diagram
BYPASS Pulldown
TEST_CLK Pulldown
1
6
25MHz
XTAL_IN
OSC
Phase
Detector
VCO
625MHz
÷5
QA[0:5]
nQA[0:5]
0
XTAL_OUT
M = ÷25
÷2, ÷5
2
QB[0:1]
nQB[0:1]
SELB Pulldown
2
QC[0:1]
nQC[0:1]
VCCO
nQA0
QA0
÷2
VCCA
BYPASS
SELB
VCC
TEST_CLK
Pin Assignment
32 31 30 29 28 27 26 25
nQC0
6
QC0
7
VCCO
8
32 VFQFN
5mm x 5mm x 0.925mm
package body
K Package
Top View
QA2
9
10 11 12 13 14 15 16
21
nQA2
20
QA3
19
nQA3
18
QA4
17
nQA4
VCCO
5
nQA1
22
QA5
4
QC1
23
nQA5
nQC1
ICS843312
VEE
3
QB1
2
VCC
QA1
nQB1
XTAL_OUT
24
QB0
1
nQB0
XTAL_IN
ICS843312AK REVISION B SEPTEMBER 28, 2010
1
©2010 Integrated Device Technology, Inc.
ICS843312 Data Sheet
CRYSTAL-TO-LVPECL CLOCK SYNTHESIZER
Table 1. Pin Descriptions
Number
Name
1,
2
XTAL_IN
XTAL_OUT
Type
Description
Input
Crystal oscillator interface. XTAL_IN is the input, XTAL_OUT is the output.
3, 32
VCC
Power
Core supply pins.
4, 5
nQC1/QC1
Output
Differential output pair. LVPECL interface levels.
6, 7
nQC0/QC0
Output
Differential output pair. LVPECL interface levels.
8, 16, 25
VCCO
Power
Output supply pins.
9, 10
nQB0/QB0
Output
Differential output pair. LVPECL interface levels.
11, 12
nQB1/QB1
Output
Differential output pair. LVPECL interface levels.
13
VEE
Power
Negative supply pin.
14, 15
nQA5/QA5
Output
Differential output pair. LVPECL interface levels.
17, 18
nQA4/QA4
Output
Differential output pair. LVPECL interface levels.
19, 20
nQA3/QA3
Output
Differential output pair. LVPECL interface levels.
21, 22
nQA2/QA2
Output
Differential output pair. LVPECL interface levels.
23, 24
nQA1/QA1
Output
Differential output pair. LVPECL interface levels.
26, 27
nQA0/QA0
Output
Differential output pair. LVPECL interface levels.
28
VCCA
Power
Analog supply pin.
29
BYPASS
Input
Pulldown
A HIGH on BYPASS signal allows TEST_CLK to propagate to output dividers and
bypass the PLL. a LOW on BYPASS signal allows VCO frequency to propagate to
the output dividers. See Table 3B. LVCMOS/LVTTL interface levels.
30
SELB
Input
Pulldown
Selects the output divider value. See Table 3A. LVCMOS/LVTTL interface levels.
31
TEST_CLK
Input
Pulldown
Single-ended input test clock. LVCMOS/LVTTL interface levels.
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
RPULLDOWN
Input Pulldown Resistor
51
kΩ
Function Tables
Table 3A. SELB Function Table
Table 3B. Bypass Function Table
Input
Input
SELB
Bank B Output Divider
BYPASS
Device Configuration
0
÷5
0
PLL Mode
1
÷2
1
Bypass the PLL
ICS843312AK REVISION B SEPTEMBER 28, 2010
2
©2010 Integrated Device Technology, Inc.
ICS843312 Data Sheet
CRYSTAL-TO-LVPECL CLOCK SYNTHESIZER
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 in the DC Characteristics or AC Characteristics is not implied. Exposure to absolute maximum rating conditions for
extended periods may affect product reliability.
Item
Rating
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
37°C/W (0 mps)
Storage Temperature, TSTG
-65°C to 150°C
DC Electrical Characteristics
Table 4A. Power Supply DC Characteristics, VCC = VCCO = 3.3V ± 5%, VEE = 0V, TA = 0°C to 70°C
Symbol
Parameter
VCC
Core Supply Voltage
VCCA
Test Conditions
Minimum
Typical
Maximum
Units
3.135
3.3
3.465
V
Analog Supply Voltage
VCC – 0.33
3.3
VCC
V
VCCO
Output Supply Voltage
3.135
3.3
3.465
V
IEE
Power Supply Current
179
mA
ICCA
Analog Supply Current
33
mA
Table 4B. Power Supply DC Characteristics, VCC = VCCO = 2.5V ± 5%, VEE = 0V, TA = 0°C to 70°C
Symbol
Parameter
VCC
Core Supply Voltage
VCCA
Test Conditions
Minimum
Typical
Maximum
Units
2.375
2.5
2.625
V
Analog Supply Voltage
VCC – 0.23
2.5
VCC
V
VCCO
Output Supply Voltage
2.375
2.5
2.625
V
IEE
Power Supply Current
168
mA
ICCA
Analog Supply Current
23
mA
Table 4C. Power Supply DC Characteristics, VCC = 3.3V ± 5%, VCCO = 2.5V ± 5%, VEE = 0V, TA = 0°C to 70°C
Symbol
Parameter
VCC
Core Supply Voltage
VCCA
Minimum
Typical
Maximum
Units
3.135
3.3
3.465
V
Analog Supply Voltage
VCC – 0.33
3.3
VCC
V
VCCO
Output Supply Voltage
2.375
2.5
2.625
V
IEE
Power Supply Current
164
mA
ICCA
Analog Supply Current
33
mA
ICS843312AK REVISION B SEPTEMBER 28, 2010
Test Conditions
3
©2010 Integrated Device Technology, Inc.
ICS843312 Data Sheet
CRYSTAL-TO-LVPECL CLOCK SYNTHESIZER
Table 4D. LVCMOS/LVTTL DC Characteristics, TA = 0°C to 70°C
Symbol
Parameter
Test Conditions
Minimum
VIH
Input High Voltage
VCC = 3.3V
VIL
Input Low Voltage
IIH
Input
High Current
TEST_CLK,
BYPASS, SELB
VCC = VIN = 3.465V or 2.625V
IIL
Input
Low Current
TEST_CLK,
BYPASS, SELB
VCC = 3.465V or 2.625V, VIN = 0V
Typical
Maximum
Units
2
VCC + 0.3
V
VCC = 2.5V
1.7
VCC + 0.3
V
VCC = 3.3V
-0.3
0.8
V
VCC = 2.5V
-0.3
0.7
V
150
µA
-5
µA
Table 4E. LVPECL DC Characteristics, VCC = VCCO = 3.3V ± 5%, VEE = 0V, TA = 0°C to 70°C
Symbol
Parameter
VOH
Output High Voltage
VOL
Output Low Voltage
VSWING
Peak-to-Peak Output Voltage Swing
Test Conditions
Minimum
Typical
Maximum
Units
VCCO - 1.4
VCCO - 0.9
V
VCCO - 2.0
VCCO - 1.7
V
0.6
1.0
V
Table 4F. LVPECL DC Characteristics, VCC = 3.3V ± 5% or 2.5V ± 5%, VCCO = 2.5V ± 5%,VEE = 0V, TA = 0°C to 70°C
Symbol
Parameter
VOH
Output High Voltage
VOL
Output Low Voltage
VSWING
Peak-to-Peak Output Voltage Swing
Test Conditions
Minimum
Typical
Maximum
Units
VCC – 1.4
VCC – 0.9
V
VCC – 2.0
VCC – 1.5
V
0.4
1.0
V
Table 5. Crystal Characteristics
Parameter
Test Conditions
Mode of Oscillation
Minimum
Typical
Maximum
Units
Fundamental
Frequency
25
MHz
Equivalent Series Resistance (ESR)
50
Ω
Shunt Capacitance
7
pF
ICS843312AK REVISION B SEPTEMBER 28, 2010
4
©2010 Integrated Device Technology, Inc.
ICS843312 Data Sheet
CRYSTAL-TO-LVPECL CLOCK SYNTHESIZER
AC Electrical Characteristics
Table 6A. AC Characteristics, VCC = VCCO = 3.3V ± 5%, VEE = 0V, TA = 0°C to 70°C
Symbol
Parameter
fOUT
Output Frequency
tjit(Ø)
RMS Phase Jitter, (Random);
NOTE 1
tR / t F
Output Rise/Fall Time
odc
Output Duty Cycle
tLOCK
PLL Lock Time
Test Conditions
Minimum
Typical
Maximum
Units
Output divider = ÷2
312.5
MHz
Output divider = ÷5
125
MHz
312.5MHz,
Integration Range: 1.875MHz - 20MHz
0.31
ps
125MHz,
Integration Range: 1.875MHz - 20MHz
0.45
ps
20% to 80%
200
700
ps
fOUT = 125MHz
45
55
%
fOUT = 312.5MHz
40
60
%
100
ms
NOTE: Electrical parameters are guaranteed over the specified ambient operating temperature range, which is established when the device is
mounted in a test socket with maintained transverse airflow greater than 500 lfpm. The device will meet specifications after thermal equilibrium
has been reached under these conditions.
NOTE 1: Refer to phase noise plots.
Table 6B. AC Characteristics, VCC = VCCO = 2.5V ± 5%, VEE = 0V, TA = 0°C to 70°C
Symbol
fOUT
tjit(Ø)
Parameter
Output Frequency
RMS Phase Jitter, (Random)
tR / t F
Output Rise/Fall Time
odc
Output Duty Cycle
tLOCK
PLL Lock Time
Test Conditions
Minimum
Typical
Maximum
Units
Output divider = ÷2
312.5
MHz
Output divider = ÷5
125
MHz
312.5MHz,
Integration Range: 1.875MHz - 20MHz
0.45
ps
125MHz,
Integration Range: 1.875MHz - 20MHz
0.55
ps
20% to 80%
200
700
ps
fOUT = 125MHz
45
55
%
fOUT = 312.5MHz
40
60
%
100
ms
NOTE: Electrical parameters are guaranteed over the specified ambient operating temperature range, which is established when the device is
mounted in a test socket with maintained transverse airflow greater than 500 lfpm. The device will meet specifications after thermal equilibrium
has been reached under these conditions.
Table 6C. AC Characteristics, VCC = 3.3V ± 5%, VCCO = 2.5V ± 5%, VEE = 0V, TA = 0°C to 70°C
Symbol
fOUT
tjit(Ø)
Parameter
Output Frequency
RMS Phase Jitter, (Random)
tR / tF
Output Rise/Fall Time
odc
Output Duty Cycle
tLOCK
PLL Lock Time
Test Conditions
Minimum
Typical
Maximum
Units
Output divider = ÷2
312.5
MHz
Output divider = ÷5
125
MHz
312.5MHz,
Integration Range: 1.875MHz - 20MHz
0.31
ps
125MHz,
Integration Range: 1.875MHz - 20MHz
0.45
ps
20% to 80%
200
700
ps
fOUT = 125MHz
45
55
%
fOUT = 312.5MHz
40
60
%
100
ms
NOTE: Electrical parameters are guaranteed over the specified ambient operating temperature range, which is established when the device is
mounted in a test socket with maintained transverse airflow greater than 500 lfpm. The device will meet specifications after thermal equilibrium
has been reached under these conditions.
ICS843312AK REVISION B SEPTEMBER 28, 2010
5
©2010 Integrated Device Technology, Inc.
ICS843312 Data Sheet
CRYSTAL-TO-LVPECL CLOCK SYNTHESIZER
Typical Phase Noise at 125MHz (3.3V)
Noise Power
dBc
Hz
125MHz
RMS Phase Jitter (Random)
1.875MHz to 20MHz = 0.45ps (typical)
Offset Frequency (Hz)
ICS843312AK REVISION B SEPTEMBER 28, 2010
6
©2010 Integrated Device Technology, Inc.
ICS843312 Data Sheet
CRYSTAL-TO-LVPECL CLOCK SYNTHESIZER
Typical Phase Noise at 312.5MHz (3.3V)
Noise Power
dBc
Hz
312.5MHz
RMS Phase Jitter (Random)
1.875MHz to 20MHz = 0.31ps (typical))
Offset Frequency (Hz)
ICS843312AK REVISION B SEPTEMBER 28, 2010
7
©2010 Integrated Device Technology, Inc.
ICS843312 Data Sheet
CRYSTAL-TO-LVPECL CLOCK SYNTHESIZER
Parameter Measurement Information
2.8V±0.04V
2V
2V
2.8V±0.04V
2V
VCC,
VCCO
Qx
SCOPE
VCC
VCCO
VCCA
VCCA
LVPECL
Qx
SCOPE
LVPECL
nQx
nQx
VEE
VEE
-1.3V±0.165V
-0.5V±0.125V
3.3V Core/ 2.5V LVPECL Output Load AC Test Circuit
3.3V Core/ 3.3V LVPECL Output Load AC Test Circuit
2V
Phase Noise Plot
VCC,
VCCO
Qx
Noise Power
2V
SCOPE
VCCA
LVPECL
nQx
VEE
f1
Offset Frequency
f2
RMS Jitter = Area Under Curve Defined by the Offset Frequency Markers
-0.5V±0.125V
RMS Phase Jitter
2.5V Core/ 2.5V LVPECL Output Load AC Test Circuit
nQAx, nQBx, nQCx
nQAx,
nQBx,
nQCx
QAx, QBx, QCx
80%
QAx,
QBx,
QCx
t PW
80%
t
VSW I N G
20%
20%
tR
odc =
tF
t PW
x 100%
t PERIOD
Output Duty Cycle/Pulse Width/Period
Output Rise/Fall Time
ICS843312AK REVISION B SEPTEMBER 28, 2010
PERIOD
8
©2010 Integrated Device Technology, Inc.
ICS843312 Data Sheet
CRYSTAL-TO-LVPECL CLOCK SYNTHESIZER
Applications Information
Power Supply Filtering Technique
As in any high speed analog circuitry, the power supply pins are
vulnerable to random noise. To achieve optimum jitter performance,
power supply isolation is required. The ICS843312 provides separate
power supplies to isolate any high switching noise from the outputs
to the internal PLL. VCC, VCCA and VCCO should be individually
connected to the power supply plane through vias, and 0.01µF
bypass capacitors should be used for each pin. Figure 1 illustrates
this for a generic VCC pin and also shows that VCCA requires that an
additional 10Ω resistor along with a 10µF bypass capacitor be
connected to the VCCA pin.
3.3V
VCC
.01µF
10Ω
.01µF
10µF
VCCA
Figure 1. Power Supply Filtering
Recommendations for Unused Input and Output Pins
Inputs:
Outputs:
TEST_CLK Input
LVPECL Outputs
For applications not requiring the use of the test clock, it can be left
floating. Though not required, but for additional protection, a 1kΩ
resistor can be tied from the TEST_CLK to ground.
All unused LVPECL outputs can be left floating. We recommend that
there is no trace attached. Both sides of the differential output pair
should either be left floating or terminated.
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 1kΩ resistor can be tied from
XTAL_IN to ground.
LVCMOS Control Pins
All control pins have internal pulldowns; additional resistance is not
required but can be added for additional protection. A 1kΩ resistor
can be used.
ICS843312AK REVISION B SEPTEMBER 28, 2010
9
©2010 Integrated Device Technology, Inc.
ICS843312 Data Sheet
CRYSTAL-TO-LVPECL CLOCK SYNTHESIZER
Crystal Input Interface
The ICS843312 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
27pF
X1
18pF Parallel Crystal
XTAL_OUT
C2
27pF
Figure 2. Crystal Input Interface
Overdriving the XTAL Interface
The XTAL_IN input can accept a single-ended LVCMOS signal
through an AC coupling capacitor. A general interface diagram is
shown in Figure 3A. The XTAL_OUT pin can be left floating. The
maximum amplitude of the input signal should not exceed 2V and the
input edge rate can be as slow as 10ns. This configuration requires
that the output impedance of the driver (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. By overdriving
the crystal oscillator, the device will be functional, but note, the device
performance is guaranteed by using a quartz crystal.
3.3V
3.3V
R1
100
Ro ~ 7 Ohm
C1
Zo = 50 Ohm
XTAL_IN
RS
43
R2
100
Driv er_LVCMOS
0.1uF
XTAL_OUT
Cry stal Input Interf ace
Figure 3A. General Diagram for LVCMOS Driver to XTAL Input Interface
VCC=3.3V
C1
Zo = 50 Ohm
XTAL_IN
R1
50
Zo = 50 Ohm
LVPECL
0.1uF
XTAL_OUT
Cry stal Input Interf ace
R2
50
R3
50
Figure 3B. General Diagram for LVPECL Driver to XTAL Input Interface
ICS843312AK REVISION B SEPTEMBER 28, 2010
10
©2010 Integrated Device Technology, Inc.
ICS843312 Data Sheet
CRYSTAL-TO-LVPECL CLOCK SYNTHESIZER
Termination for 3.3V LVPECL Outputs
The clock layout topology shown below is a typical termination for
LVPECL outputs. The two different layouts mentioned are
recommended only as guidelines.
transmission lines. Matched impedance techniques should be used
to maximize operating frequency and minimize signal distortion.
Figures 4A and 4B 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.
The differential outputs 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 drive 50Ω
R3
125Ω
3.3V
3.3V
Zo = 50Ω
3.3V
R4
125Ω
3.3V
3.3V
Zo = 50Ω
+
+
_
LVPECL
Input
Zo = 50Ω
_
LVPECL
R1
50Ω
R2
50Ω
R1
84Ω
VCC - 2V
RTT =
1
* Zo
((VOH + VOL) / (VCC – 2)) – 2
Input
Zo = 50Ω
R2
84Ω
RTT
Figure 4A. 3.3V LVPECL Output Termination
ICS843312AK REVISION B SEPTEMBER 28, 2010
Figure 4B. 3.3V LVPECL Output Termination
11
©2010 Integrated Device Technology, Inc.
ICS843312 Data Sheet
CRYSTAL-TO-LVPECL CLOCK SYNTHESIZER
Termination for 2.5V LVPECL Outputs
level. The R3 in Figure 5B can be eliminated and the termination is
shown in Figure 5C.
Figure 5A and Figure 5B show examples of termination for 2.5V
LVPECL driver. These terminations are equivalent to terminating 50Ω
to VCC – 2V. For VCCO = 2.5V, the VCCO – 2V is very close to ground
2.5V
VCC = 2.5V
2.5V
2.5V
VCC = 2.5V
R1
250Ω
R3
250Ω
50Ω
+
50Ω
+
50Ω
–
50Ω
2.5V LVPECL Driver
–
R1
50Ω
2.5V LVPECL Driver
R2
62.5Ω
R2
50Ω
R4
62.5Ω
R3
18Ω
Figure 5A. 2.5V LVPECL Driver Termination Example
Figure 5B. 2.5V LVPECL Driver Termination Example
2.5V
VCC = 2.5V
50Ω
+
50Ω
–
2.5V LVPECL Driver
R1
50Ω
R2
50Ω
Figure 5C. 2.5V LVPECL Driver Termination Example
ICS843312AK REVISION B SEPTEMBER 28, 2010
12
©2010 Integrated Device Technology, Inc.
ICS843312 Data Sheet
CRYSTAL-TO-LVPECL CLOCK SYNTHESIZER
VFQFN EPAD Thermal Release Path
In order to maximize both the removal of heat from the package and
the electrical performance, a land pattern 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 6. 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.
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, please refer to the Application
Note on the Surface Mount Assembly of Amkor’s Thermally/
Electrically Enhance Leadframe Base Package, Amkor Technology.
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”) are application specific
PIN
PIN PAD
SOLDER
EXPOSED HEAT SLUG
GROUND PLANE
THERMAL VIA
SOLDER
LAND PATTERN
(GROUND PAD)
PIN
PIN PAD
Figure 6. P.C. Assembly for Exposed Pad Thermal Release Path – Side View (drawing not to scale)
ICS843312AK REVISION B SEPTEMBER 28, 2010
13
©2010 Integrated Device Technology, Inc.
ICS843312 Data Sheet
CRYSTAL-TO-LVPECL CLOCK SYNTHESIZER
Power Considerations
This section provides information on power dissipation and junction temperature for the ICS843312.
Equations and example calculations are also provided.
1.
Power Dissipation.
The total power dissipation for the ICS843312 is the sum of the core power plus the power dissipation in the load(s).
The following is the power dissipation for VCCO = 3.3V + 5% = 3.465V, which gives worst case results.
NOTE: Please refer to Section 3 for details on calculating power dissipation in the load.
•
Power (core)MAX = VCC_MAX * IEE_MAX = 3.465V * 179mA = 620.235mW
•
Power (outputs)MAX = 30mW/Loaded Output pair
If all outputs are loaded, the total power is 10 * 30mW = 300mW
Total Power_MAX (3.3V, with all outputs switching) = 620.235mW + 300mW = 920.235mW
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 is 125°C. Limiting the internal transistor junction temperature, Tj, to 125°C ensures that the bond
wire and bond pad temperature remains below 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 7 below.
Therefore, Tj for an ambient temperature of 70°C with all outputs switching is:
70°C + 0.920W * 37°C/W = 104°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 (multi-layer).
Table 7. Thermal Resistance θJA for 32 Lead VFQFN, Forced Convection
θJA by Velocity
Meters per Second
Multi-Layer PCB, JEDEC Standard Test Boards
ICS843312AK REVISION B SEPTEMBER 28, 2010
0
1
2.5
37.0°C/W
32.4°C/W
29.0°C/W
14
©2010 Integrated Device Technology, Inc.
ICS843312 Data Sheet
CRYSTAL-TO-LVPECL CLOCK SYNTHESIZER
3. Calculations and Equations.
The purpose of this section is to calculate the power dissipation for the LVPECL output pairs.
The LVPECL output driver circuit and termination are shown in Figure 7.
VCC
Q1
VOUT
RL
50Ω
VCC - 2V
Figure 7. 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
VCCO – 2V.
•
For logic high, VOUT = VOH_MAX = VCCO_MAX – 0.9V
(VCC_MAX – VOH_MAX) = 0.9V
•
For logic low, VOUT = VOL_MAX = VCCO_MAX – 1.7V
(VCCO_MAX – VOL_MAX) = 1.7V
Pd_H is power dissipation when the output drives high.
Pd_L is the power dissipation when the output drives low.
Pd_H = [(VOH_MAX – (VCCO_MAX – 2V))/RL] * (VCCO_MAX – VOH_MAX) = [(2V – (VCCO_MAX – VOH_MAX))/RL] * (VCCO_MAX – VOH_MAX) =
[(2V – 0.9V)/50Ω] * 0.9V = 19.8mW
Pd_L = [(VOL_MAX – (VCCO_MAX – 2V))/RL] * (VCCO_MAX – VOL_MAX) = [(2V – (VCCO_MAX – VOL_MAX))/RL] * (VCCO_MAX – VOL_MAX) =
[(2V – 1.7V)/50Ω] * 1.7V = 10.2mW
Total Power Dissipation per output pair = Pd_H + Pd_L = 30mW
ICS843312AK REVISION B SEPTEMBER 28, 2010
15
©2010 Integrated Device Technology, Inc.
ICS843312 Data Sheet
CRYSTAL-TO-LVPECL CLOCK SYNTHESIZER
Reliability Information
Table 8. θJA vs. Air Flow Table for a 32Lead 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 ICS843312 is: 3059
ICS843312AK REVISION B SEPTEMBER 28, 2010
16
©2010 Integrated Device Technology, Inc.
ICS843312 Data Sheet
CRYSTAL-TO-LVPECL CLOCK SYNTHESIZER
Package Outline and Package Dimensions
Package Outline - K Suffix for 32 Lead VFQFN
(Ref.)
S eating Plan e
N &N
Even
(N -1)x e
(R ef.)
A1
Ind ex Area
A3
N
L
N
Anvil
Anvil
Singulation
Singula tion
e (Ty p.)
2 If N & N
1
are Even
2
OR
E2
(N -1)x e
(Re f.)
E2
2
To p View
b
A
(Ref.)
D
Chamfer 4x
0.6 x 0.6 max
OPTIONAL
e
N &N
Odd
0. 08
C
D2
2
Th er mal
Ba se
D2
C
Bottom View w/Type A ID
Bottom View w/Type B ID
Bottom View w/Type C ID
BB
4
CHAMFER
4
N N-1
There are 3 methods of indicating pin 1 corner
at the back of the VFQFN package are:
1. Type A: Chamfer on the paddle (near pin 1)
2. Type B: Dummy pad between pin 1 and N.
3. Type C: Mouse bite on the paddle (near pin 1)
2
1
2
1
CC
2
1
4
N N-1
DD
4
RADIUS
4
N N-1
AA
4
Table 9. Package Dimensions
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 9.
JEDEC Variation: VHHD-2/-4
All Dimensions in Millimeters
Symbol
Minimum
Nominal
Maximum
N
32
A
0.80
1.00
A1
0
0.05
A3
0.25 Ref.
b
0.18
0.25
0.30
8
ND & NE
D&E
5.00 Basic
D2 & E2
3.0
3.3
e
0.50 Basic
L
0.30
0.40
0.50
Reference Document: JEDEC Publication 95, MO-220
ICS843312AK REVISION B SEPTEMBER 28, 2010
17
©2010 Integrated Device Technology, Inc.
ICS843312 Data Sheet
CRYSTAL-TO-LVPECL CLOCK SYNTHESIZER
Ordering Information
Table 10. Ordering Information
Part/Order Number
Marking
Package
Shipping Packaging
Temperature
843312AKLF
ICS843312AL
“Lead-Free” 32 Lead VFQFN
Tray
0°C to 70°C
843312AKLFT
ICS843312AL
“Lead-Free” 32 Lead VFQFN
2500 Tape & Reel
0°C to 70°C
NOTE: Parts that are ordered with an "LF" suffix to the part 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 (IDT) assumes no responsibility for either its use or for the
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 ranges, 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.
ICS843312AK REVISION B SEPTEMBER 28, 2010
18
©2010 Integrated Device Technology, Inc.
ICS843312 Data Sheet
CRYSTAL-TO-LVPECL CLOCK SYNTHESIZER
Revision History Sheet
Rev
B
Table
T6A - T6C
Page
1
5
10
17
Description of Change
Date
Block Diagram - added outline to distinguish crystal oscillator is inside the part.
AC Characteristics Tables - added Output Duty Cycle spec for 312.5MHz.
Updated Overdriving the XTAL Interface.
Updated Package Outline.
ICS843312AK REVISION B SEPTEMBER 28, 2010
19
9/28/10
©2010 Integrated Device Technology, Inc.
ICS843312 Data Sheet
CRYSTAL-TO-LVPECL CLOCK SYNTHESIZER
We’ve Got Your Timing Solution
6024 Silver Creek Valley Road
San Jose, California 95138
Sales
800-345-7015 (inside USA)
+408-284-8200 (outside USA)
Fax: 408-284-2775
www.IDT.com/go/contactIDT
Technical Support
netcom@idt.com
+480-763-2056
DISCLAIMER Integrated Device Technology, Inc. (IDT) and its subsidiaries reserve the right to modify the products and/or specifications described herein at any time and at IDT’s sole discretion. All information in this document,
including descriptions of product features and performance, is subject to change without notice. Performance specifications and the operating parameters of the described products are determined in the independent state and are not
guaranteed to perform the same way when installed in customer products. The information contained herein is provided without representation or warranty of any kind, whether express or implied, including, but not limited to, the
suitability of IDT’s products for any particular purpose, an implied warranty of merchantability, or non-infringement of the intellectual property rights of others. This document is presented only as a guide and does not convey any
license under intellectual property rights of IDT or any third parties.
IDT’s products are not intended for use in life support systems or similar devices where the failure or malfunction of an IDT product can be reasonably expected to significantly affect the health or safety of users. Anyone using an IDT
product in such a manner does so at their own risk, absent an express, written agreement by IDT.
Integrated Device Technology, IDT and the IDT logo are registered trademarks of IDT. Other trademarks and service marks used herein, including protected names, logos and designs, are the property of IDT or their respective third
party owners.
Copyright 2010. All rights reserved.
