IDT 8S89874BKILFT

1:2 Differential-to-LVPECL Buffer/Divider
ICS8S89874I
DATA SHEET
General Description
Features
The ICS8S89874I is a high speed 1:2 Differential-to- LVPECL Buffer/
Divider. The ICS8S89874I has a selectable ÷1, ÷2, ÷4, ÷8, ÷16
output divider, which allows the device to be used as either a 1:2
fanout buffer or frequency divider. The clock input has internal
termination resistors, allowing it to interface with several differential
signal types while minimizing the number of required external
components. The device is packaged in a small, 3mm x 3mm
VFQFN package, making it ideal for use on space-constrained
boards.
•
•
Two LVPECL/ECL output pairs
•
IN, nIN input can accept the following differential input levels:
LVPECL, LVDS, CML
•
•
•
•
•
•
•
•
Output frequency: 2GHz (maximum)
Frequency divide select options: ÷1 (pass through), ÷2, ÷4, ÷8,
÷16
Output skew: 15ps (maximum)
Part-to-part skew: 250ps (maximum)
Additive phase jitter, RMS: 0.20ps (typical)
LVPECL supply voltage range: 2.375V to 3.63V
ECL supply voltage range: -3.63V to -2.375V
-40°C to 85°C ambient operating temperature
Available in lead-free (RoHS 6) package
2
11 VT
Q1 3
00
01
10
11
50Ω
VT
50Ω
nIN
10 VREF_AC
nQ1 4
Q1
÷2
÷4
÷8
÷16
nQ1
S2
nQ0
6
7
8
VCC
9 nIN
5
0
nRESET
Q0
1
IN
VCC
16 15 14 13
12 IN
nQ0
Enable
FF
Enable
MUX
ICS8S89874I
16-Lead VFQFN
3mm x 3mm x 0.925mm package body
K Package
Top View
S0 Pullup
S1 Pullup
Q0 1
nc
nRESET Pullup
VEE
S0
S2 Pullup
S1
Pin Assignment
Block Diagram
Decoder
VREF_AC
ICS8S89874BKI REVISION A OCTOBER 22, 2010
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©2010 Integrated Device Technology, Inc.
ICS8S89874I Data Sheet
1:2 DIFFERENTIAL-TO-LVPECL BUFFER/DIVIDER
Table 1. Pin Descriptions
Number
Name
1, 2
Q0, nQ0
Output
Type
Differential output pair. LVPECL/ECL interface levels.
Description
3, 4
Q1, nQ1
Output
Differential output pair. LVPECL/ECL interface levels.
5, 15, 16
S2, S1, S0
Input
6
nc
Unused
7, 14
Vcc
Power
8
nRESET
Input
Pullup
Select pins. LVCMOS/LVTTL interface levels.
No connect.
Positive supply pins.
Pullup
When LOW, resets the divider. Pulled HIGH when left unconnected. Input threshold
is VCC/2. Includes a 37kΩ pullup resistor. LVTTL/LVCMOS interface levels.
Inverting differential LVPECL clock input. RT = 50Ω termination to VT.
9
nIN
Input
10
VREF_AC
Output
11
VT
Input
Termination input.
12
IN
Input
Non-inverting LVPECL differential clock input. RT = 50Ω termination to VT.
13
VEE
Power
Negative supply pin.
Reference voltage for AC-coupled applications.
NOTE: Pullup refers to internal input resistors. See Table 2, Pin Characteristics, for typical values.
Table 2. Pin Characteristics
Symbol
Parameter
RPULLUP
Input Pullup Resistor
ICS8S89874BKI REVISION A OCTOBER 22, 2010
Test Conditions
Minimum
Typical
37
2
Maximum
Units
kΩ
©2010 Integrated Device Technology, Inc.
ICS8S89874I Data Sheet
1:2 DIFFERENTIAL-TO-LVPECL BUFFER/DIVIDER
Function Tables
Table 3A. Control Input Function Table
Inputs
Outputs
nRESET
Selected Source
Q0, Q1
nQ0, nQ1
0
IN/nIN
Disabled; LOW
Disabled; HIGH
1
IN/nIN
Enabled
Enabled
VCC/2
nRESET
tRR
IN
nIN
VIN
VIN Swing
tPD
nQx
VOUT Swing
Qx
Figure 1. nRESET Timing Diagram
Table 3B. Truth Table
Inputs
nRESET
S2
S1
S0
Outputs
1
0
X
X
Reference Clock ÷1 (pass through)
1
1
0
0
Reference Clock ÷2
1
1
0
1
Reference Clock ÷4
1
1
1
0
Reference Clock ÷8
1
1
1
1
Reference Clock ÷16
0
1
X
X
Q = LOW, nQ = HIGH; Clock Disabled
0
0
X
X
Q = LOW, nQ = HIGH; Clock Disabled
ICS8S89874BKI REVISION A OCTOBER 22, 2010
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©2010 Integrated Device Technology, Inc.
ICS8S89874I Data Sheet
1:2 DIFFERENTIAL-TO-LVPECL BUFFER/DIVIDER
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
-0.5V to + 4.6V
Inputs, VI
-0.5V to VCC + 0.5V
Outputs, IO
Continuous Current
Surge Current
50mA
100mA
Input Current, IN, nIN
±50mA
VT Current, IVT
±100mA
VREF_AC Input Sink/Source, IREF_AC
±2mA
Operating Temperature Range, TA
-40°C to +85°C
Package Thermal Impedance, θJA, (Junction-to-Ambient)
74.7°C/W (0 mps)
Storage Temperature, TSTG
-65°C to 150°C
DC Electrical Characteristics
Table 4A. Power Supply DC Characteristics, VCC = 3.3V ± 10% or 2.5V ± 5%, VEE = 0V, TA = -40°C to 85°C
Symbol
Parameter
VCC
Positive Supply Voltage
IEE
Power Supply Current
Test Conditions
Minimum
Typical
Maximum
Units
2.375
3.3
3.63
V
45
mA
Table 4B. LVCMOS/LVTTL DC Characteristics, VCC = 3.3V ± 10% or 2.5V ± 5%, VEE = 0V, TA = -40°C to 85°C
Symbol
Parameter
VIH
Input High Voltage
VIL
Input Low Voltage
IIH
Input High Current
VCC = VIN = 3.63V or 2.625V
IIL
Input Low Current
VCC = 3.63V or 2.625V, VIN = 0V
ICS8S89874BKI REVISION A OCTOBER 22, 2010
Test Conditions
Minimum
4
Maximum
Units
2.2
VCC + 0.3
V
0
0.8
V
10
µA
-150
Typical
µA
©2010 Integrated Device Technology, Inc.
ICS8S89874I Data Sheet
1:2 DIFFERENTIAL-TO-LVPECL BUFFER/DIVIDER
Table 4C. Differential DC Characteristics, VCC = 3.3V ± 10% or 2.5V ± 5%, VEE = 0V, TA = -40°C to 85°C
Symbol
Parameter
RIN
Differential Input Resistance
VIH
Test Conditions
Minimum
Typical
Maximum
Units
(IN, nIN)
40
50
60
Ω
Input High Voltage
(IN, nIN)
1.2
VCC
V
VIL
Input Low Voltage
(IN, nIN)
0
VIH – 0.15
V
VIN
Input Voltage Swing
0.15
1.2
V
VDIFF_IN
Differential Input Voltage Swing
0.3
IIN
Input Current; NOTE 1
VREF_AC
Bias Voltage
V
(IN, nIN)
VCC – 1.45
VCC – 1.37
35
mA
VCC – 1.32
V
NOTE 1: Guaranteed by design.
Table 4D. LVPECL DC Characteristics, VCC = 3.3V ± 10% or 2.5V ± 5%, VEE = 0V, TA = -40°C to 85°C
Symbol
Parameter
VOH
Output High Voltage; NOTE 1
VOL
Output Low Voltage; NOTE 1
VOUT
VDIFF_OUT
Test Conditions
Minimum
Typical
Maximum
Units
VCC – 1.175
VCC – 0.82
V
VCC – 2.0
VCC – 1.575
V
Output Voltage Swing
0.6
1.0
V
Differential Output Voltage Swing
1.2
2.0
V
NOTE: Input and output parameters vary 1:1 with VCC.
NOTE 1: Outputs terminated with 50Ω to VCC – 2V.
ICS8S89874BKI REVISION A OCTOBER 22, 2010
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©2010 Integrated Device Technology, Inc.
ICS8S89874I Data Sheet
1:2 DIFFERENTIAL-TO-LVPECL BUFFER/DIVIDER
AC Electrical Characteristics
Table 5. AC Characteristics, VCC = 3.3V ± 10% or 2.5V ± 5%, VEE = 0V, TA = -40°C to 85°C
Symbol
Parameter
fOUT
Output Frequency
fIN
Input Frequency
tPD
Propagation Delay; (Differential);
NOTE 1
tsk(o)
Output Skew; NOTE 2, 4
tsk(pp)
Part-to-Part Skew; NOTE 3, 4
tjit
Buffer Additive Jitter; RMS; refer to
Additive Phase Jitter Section; NOTE 5
tRR
Reset Recovery time
tR / tF
Output Rise/Fall Time
Test Conditions
Minimum
Typical
Maximum
Units
Output Swing ≥ 450mV
2
GHz
÷2, ÷4, ÷8, ÷16
2.5
GHz
Input Swing: <400mV
460
640
840
ps
Input Swing: ≥ 400mV
430
615
810
ps
15
ps
250
ps
155.52MHz, Integration Range:
12kHz – 20MHz
0.20
ps
600
20% to 80%
70
ps
250
ps
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: All parameters characterized at ≤ 1GHz, 800mV input signal, unless otherwise noted.
NOTE 1: Measured from the differential input crossing point to the differential output crossing point.
NOTE 2: Defined as skew between outputs at the same supply voltage and with equal load conditions.
Measured at the output differential cross points.
NOTE 3: Defined as skew between outputs on different devices operating at the same supply voltage, same temperature, same frequency and
with equal load conditions. Using the same type of inputs on each device, the outputs are measured at the differential cross points.
NOTE 4: This parameter is defined in accordance with JEDEC Standard 65.
NOTE 5: Pass through, ÷1 mode.
ICS8S89874BKI REVISION A OCTOBER 22, 2010
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©2010 Integrated Device Technology, Inc.
ICS8S89874I Data Sheet
1:2 DIFFERENTIAL-TO-LVPECL BUFFER/DIVIDER
Additive Phase Jitter
The spectral purity in a band at a specific offset from the fundamental
compared to the power of the fundamental is called the dBc Phase
Noise. This value is normally expressed using a Phase noise plot
and is most often the specified plot in many applications. Phase noise
is defined as the ratio of the noise power present in a 1Hz band at a
specified offset from the fundamental frequency to the power value of
the fundamental. This ratio is expressed in decibels (dBm) or a ratio
of the power in the 1Hz band to the power in the fundamental. When
the required offset is specified, the phase noise is called a dBc value,
which simply means dBm at a specified offset from the fundamental.
By investigating jitter in the frequency domain, we get a better
understanding of its effects on the desired application over the entire
time record of the signal. It is mathematically possible to calculate an
expected bit error rate given a phase noise plot.
SSB Phase Noise dBc/Hz
Additive Phase Jitter @ 155.52MHz
12kHz to 20MHz = 0.20ps (typical)
Offset from Carrier Frequency (Hz)
As with most timing specifications, phase noise measurements has
issues relating to the limitations of the equipment. Often the noise
floor of the equipment is higher than the noise floor of the device. This
is illustrated above. The device meets the noise floor of what is
shown, but can actually be lower. The phase noise is dependent on
the input source and measurement equipment.
ICS8S89874BKI REVISION A OCTOBER 22, 2010
The source generator IFR2042 and Agilent 8133 were the external
input to drive the input clock, IN, nIN.
7
©2010 Integrated Device Technology, Inc.
ICS8S89874I Data Sheet
1:2 DIFFERENTIAL-TO-LVPECL BUFFER/DIVIDER
Parameter Measurement Information
2V
VCC
VCC
Qx
SCOPE
nIN
V
Cross Points
IN
V
IH
IN
LVPECL
nQx
V
VEE
IL
VEE
-0.375V to -1.63V
Output Load AC Test Circuit
Differential Input Level
nQx
Par t 1
nQx
Qx
Qx
nQy
nQy
Par t 2
Qy
Qy
tsk(o)
tsk(pp)
Part-to-Part Skew
Output Skew
nIN
VDIFF_IN
VIN
IN
nQ0, nQ1
Q0, Q1
Differential Voltage Swing = 2 x Single-ended VIN
tPD
Single-ended & Differential Input Voltage Swing
Propagation Delay
nQ0, nQ1
80%
80%
VSW I N G
20%
20%
Q0, Q1
tR
tF
Output Rise/Fall Time
ICS8S89874BKI REVISION A OCTOBER 22, 2010
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©2010 Integrated Device Technology, Inc.
ICS8S89874I Data Sheet
1:2 DIFFERENTIAL-TO-LVPECL BUFFER/DIVIDER
Applications Information
3.3V Differential Input with Built-In 50Ω Termination Interface
the most common driver types. The input interfaces suggested here
are examples only. If the driver is from another vendor, use their
termination recommendation. Please consult with the vendor of the
driver component to confirm the driver termination requirements.
The IN /nIN with built-in 50Ω terminations accept LVDS, LVPECL,
CML and other differential signals. Both signals must meet the VIN
and VIH input requirements. Figures 2A to 2D show interface
examples for the IN/nIN input with built-in 50Ω terminations driven by
3.3V
3.3V
3.3V
3.3V
Zo = 50Ω
Zo = 50Ω
IN
IN
VT
Zo = 50Ω
VT
Zo = 50Ω
nIN
nIN
Receiver
LVDS
Receiver
LVPECL
With
With
R1
50Ω
Built-In
Built-In
50Ω
50Ω
Figure 2B. IN/nIN Input with Built-In 50Ω
Driven by an LVPECL Driver
Figure 2A. N/nIN Input with Built-In 50Ω
Driven by an LVDS Driver
3.3V
3.3V
3.3V
3.3V
Zo = 50Ω
Zo = 50Ω
IN
IN
Zo = 50Ω
Zo = 50Ω
VT
nIN
nIN
Receiver
CML – Open Collector
VT
CML – Built-in 50Ω Pull-up
With
Receiver
With
Built-In
Built-In
50Ω
50Ω
Figure 2D. IN/nIN Input with Built-In 50Ω Driven by a
CML Driver with Built-In 50Ω Pullup
Figure 2C. IN/nIN Input with Built-In 50Ω
Driven by a CML Driver
ICS8S89874BKI REVISION A OCTOBER 22, 2010
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©2010 Integrated Device Technology, Inc.
ICS8S89874I Data Sheet
1:2 DIFFERENTIAL-TO-LVPECL BUFFER/DIVIDER
2.5V LVPECL Input with Built-In 50Ω Termination Interface
the most common driver types. The input interfaces suggested here
are examples only. If the driver is from another vendor, use their
termination recommendation. Please consult with the vendor of the
driver component to confirm the driver termination requirements.
The IN /nIN with built-in 50Ω terminations accept LVDS, LVPECL,
CML and other differential signals. Both signals must meet the VIN
and VIH input requirements. Figures 3A to 3D show interface
examples for the IN/nIN with built-in 50Ω termination input driven by
2.5V
2.5V
2.5V
3.3V or 2.5V
Zo = 50Ω
Zo = 50Ω
IN
IN
VT
Zo = 50Ω
VT
Zo = 50Ω
nIN
nIN
Receiver
LVDS
Receiver
LVPECL
With
With
R1
18Ω
Built-In
Built-In
50Ω
50Ω
Figure 3B. IN/nIN Input with Built-In 50Ω
Driven by an LVPECL Driver
Figure 3A. IN/nIN Input with Built-In 50Ω
Driven by an LVDS Driver
2.5V
2.5V
2.5V
Zo = 50Ω
2.5V
Zo = 50Ω
IN
Zo = 50Ω
IN
VT
Zo = 50Ω
nIN
nIN
Receiver
CML
CML - Built-in 50Ω Pull-up
With
Receiver
With
Built-In
Built-In
50Ω
50Ω
Figure 3C. IN/nIN Input with Built-In 50Ω
Driven by a CML Driver
ICS8S89874BKI REVISION A OCTOBER 22, 2010
VT
Figure 3D. IN/nIN Input with Built-In 50Ω Driven by a
CML Driver with Built-In 50Ω Pullup
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©2010 Integrated Device Technology, Inc.
ICS8S89874I Data Sheet
1:2 DIFFERENTIAL-TO-LVPECL BUFFER/DIVIDER
Recommendations for Unused Input and Output Pins
Inputs:
Outputs:
LVCMOS Control Pins
LVPECL Outputs
All control pins has internal pullups; additional resistance is not
required but can be added for additional protection. A 1kΩ resistor
can be used.
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.
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
R2
84Ω
RTT
Figure 4A. 3.3V LVPECL Output Termination
ICS8S89874BKI REVISION A OCTOBER 22, 2010
Input
Zo = 50Ω
Figure 4B. 3.3V LVPECL Output Termination
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©2010 Integrated Device Technology, Inc.
ICS8S89874I Data Sheet
1:2 DIFFERENTIAL-TO-LVPECL BUFFER/DIVIDER
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 VCC = 2.5V, the VCC – 2V is very close to ground
2.5V
VCC = 2.5V
2.5V
2.5V
VCC = 2.5V
R1
250Ω
50Ω
R3
250Ω
+
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
ICS8S89874BKI REVISION A OCTOBER 22, 2010
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©2010 Integrated Device Technology, Inc.
ICS8S89874I Data Sheet
1:2 DIFFERENTIAL-TO-LVPECL BUFFER/DIVIDER
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)
ICS8S89874BKI REVISION A OCTOBER 22, 2010
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©2010 Integrated Device Technology, Inc.
ICS8S89874I Data Sheet
1:2 DIFFERENTIAL-TO-LVPECL BUFFER/DIVIDER
Power Considerations
This section provides information on power dissipation and junction temperature for the ICS8S89874I.
Equations and example calculations are also provided.
1.
Power Dissipation.
The total power dissipation for the ICS8S89874I is the sum of the core power plus the power dissipated in the load(s).
The following is the power dissipation for VCC = 3.63V, 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 = 3.63V * 45mA = 163.35mW
•
Power (outputs)MAX = 32.62mW/Loaded Output pair
If all outputs are loaded, the total power is 2 * 32.62mW = 65.24mW
•
Power Dissipation for internal termination RT
Power (RT)MAX = (VIN_MAX)2 / RT_MIN = (1.2V)2 / 80Ω = 18mW
Total Power_MAX = (3.63V, with all outputs switching) = 163.35mW + 65.24mW + 18mW = 246.59mW
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 74.7°C/W per Table 6 below.
Therefore, Tj for an ambient temperature of 85°C with all outputs switching is:
85°C + 0.247W * 74.7°C/W = 103.5°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 6. Thermal Resistance θJA for 16 Lead VFQFN, Forced Convection
θJA vs. Air Flow
Meters per Second
Multi-Layer PCB, JEDEC Standard Test Boards
ICS8S89874BKI REVISION A OCTOBER 22, 2010
0
1
2.5
74.7°C/W
65.3°C/W
58.5°C/W
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©2010 Integrated Device Technology, Inc.
ICS8S89874I Data Sheet
1:2 DIFFERENTIAL-TO-LVPECL BUFFER/DIVIDER
3. Calculations and Equations.
The purpose of this section is to calculate the power dissipation for the LVPECL output pairs.
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
VCC – 2V.
•
For logic high, VOUT = VOH_MAX = VCC_MAX – 0.82V
(VCC_MAX – VOH_MAX) = 0.82V
•
For logic low, VOUT = VOL_MAX = VCC_MAX – 1.58V
(VCC_MAX – VOL_MAX) = 1.58V
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 – (VCC_MAX – 2V))/RL] * (VCC_MAX – VOH_MAX) = [(2V – (VCC_MAX – VOH_MAX))/RL] * (VCC_MAX – VOH_MAX) =
[(2V – 0.82V)/50Ω] * 0.82V = 19.35mW
Pd_L = [(VOL_MAX – (VCC_MAX – 2V))/RL] * (VCC_MAX – VOL_MAX) = [(2V – (VCC_MAX – VOL_MAX))/RL] * (VCO_MAX – VOL_MAX) =
[(2V – 1.58V)/50Ω] * 1.58V = 13.27mW
Total Power Dissipation per output pair = Pd_H + Pd_L = 32.62mW
ICS8S89874BKI REVISION A OCTOBER 22, 2010
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ICS8S89874I Data Sheet
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Reliability Information
Table 7. θJA vs. Air Flow Table for a 16 Lead VFQFN
θJA by Velocity
Meters per Second
Multi-Layer PCB, JEDEC Standard Test Boards
0
1
2.5
74.7°C/W
65.3°C/W
58.5°C/W
Transistor Count
The transistor count for ICS8S89874I is: 489
Pin compatible with ICS889874
ICS8S89874BKI REVISION A OCTOBER 22, 2010
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Package Outline and Package Dimensions
Package Outline - K Suffix for 16 Lead VFQFN
(Ref.)
Seating Plane
ND & NE
Even
(ND-1)x e
(R ef.)
A1
Index Area
A3
N
Top View
L
N
e (Typ.)
2 If ND & NE
1
Anvil
Singulation
or
Sawn
Singulation
are Even
2
E2
(NE -1)x e
(Re f.)
E2
2
b
A
(Ref.)
D
Chamfer 4x
0.6 x 0.6 max
OPTIONAL
e
ND & NE
Odd
0. 08
C
D2
2
Thermal
Base
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 8. Package Dimensions
JEDEC Variation: VEED-2/-4
All Dimensions in Millimeters
Symbol
Minimum
Maximum
N
16
A
0.80
1.00
A1
0
0.05
A3
0.25 Ref.
b
0.18
0.30
4
ND & NE
D&E
3.00 Basic
D2 & E2
1.00
1.80
e
0.50 Basic
L
0.30
0.50
Reference Document: JEDEC Publication 95, MO-220
ICS8S89874BKI REVISION A OCTOBER 22, 2010
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Ordering Information
Table 9. Ordering Information
Part/Order Number
8S89874BKILF
8S89874BKILFT
Marking
874B
874B
Package
“Lead-Free” 16 Lead VFQFN
“Lead-Free” 16 Lead VFQFN
Shipping Packaging
Tube
2500 Tape & Reel
Temperature
-40°C to 85°C
-40°C to 85°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 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.
ICS8S89874BKI REVISION A OCTOBER 22, 2010
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©2010 Integrated Device Technology, Inc.
ICS8S89874I Data Sheet
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