ALSC ASM2I99448G-32-ET 3.3v/2.5v lvcmos 1:12 clock fanout buffer Datasheet

ASM2I99448
May 2005
rev 0.3
3.3V/2.5V LVCMOS 1:12 Clock Fanout Buffer
Features
The ASM2I99448 is specifically designed to distribute
LVCMOS compatible clock signals up to a frequency of
ƒ
12 LVCMOS compatible clock outputs
ƒ
Selectable LVCMOS and differential LVPECL
350MHz. Each output provides a precise copy of the input
signal with a near zero skew. The outputs buffers support
compatible clock inputs
driving of 50Ω terminated transmission lines on the incident
ƒ
Maximum clock frequency of 350MHz
ƒ
Maximum clock skew of 150pS
ƒ
Synchronous output stop in logic low state
edge: each output is capable of driving either one parallel
terminated or two series terminated transmission lines.
eliminates output runt pulses
Two selectable, independent clock inputs are available,
providing support of LVCMOS and differential LVPECL
ƒ
High–impedance output control
clock distribution systems. The ASM2I99448 CLK_STOP
ƒ
3.3V or 2.5V power supply
control is synchronous to the falling edge of the input clock.
ƒ
Drives up to 24 series terminated clock lines
It allows the start and stop of the output clock signal only in
ƒ
Ambient temperature range –40°C to +85°C
a logic low state, thus eliminating potential output runt
ƒ
32–Lead LQFP & TQFP packaging
pulses. Applying the OE control will force the outputs into
ƒ
Supports
ƒ
clock
distribution
in
networking,
high–impedance mode.
telecommunication and computing applications
All inputs have an internal pull–up or pull–down resistor
Pin and Function compatible to MPC9448 and
preventing unused and open inputs from floating. The
device supports a 2.5V or 3.3V power supply and an
MPC948
ambient temperature range of –40°C to +85°C. The
Functional Description
ASM2I99448
The ASM2I99448 is a 3.3V or 2.5V compatible, 1:12 clock
performance–enhanced to the MPC948.
is
pin
and
function
compatible
fanout buffer targeted for high performance clock tree
applications. With output frequencies up to 350 MHz and
output skews less than 150 pS, the device meets the needs
of most demanding clock applications.
Alliance Semiconductor
2575, Augustine Drive • Santa Clara, CA • Tel: 408.855.4900 • Fax: 408.855.4999 • www.alsc.com
Notice: The information in this document is subject to change without notice.
but
ASM2I99448
May 2005
rev 0.3
Q5
GND
Q6
VCC
Q7
19
18
17
VCC
26
15
Q8
Q2
27
14
VCC
GND
28
13
Q9
Q1
29
12
GND
VCC
30
11
Q10
Q8
Q0
31
10
VCC
Q9
GND
32
9
Q11
VCC
Q7
SYNC
Q10
VCC
1
2
3
4
5
6
7
8
GND
Q6
CLK_SEL
VCC
ASM2I99448
Q5
OE
Q3
OE
20
GND
Q4
CLK_STOP
21
16
Q2
VCC
22
CLK_STOP
STOP
23
25
PCLK
1
24
Q3
Q1
PCLK
CCLK
Q0
CLK
CCLK
0
CLK_SEL
PCLK
PCLK
VCC
VCC
Q4
Pin Diagram
GND
Block Diagram
Q11
(All input resistors have a value of 25KΩ)
Table 1. FUNCTION TABLE
Control
CLK_SEL
Default
1
0
1
PECL differential input selected
CCLK input selected
1
OE
1
Outputs disabled (high-impedance state)
CLK_STOP
1
Outputs synchronously stopped in logic low
state
Outputs enabled
Outputs active
Note: 1. OE=0 will high-impedance tristate all outputs independent on CLK_STOP.
3.3V/2.5V LVCMOS 1:12 Clock Fanout Buffer
Notice: The information in this document is subject to change without notice.
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ASM2I99448
May 2005
rev 0.3
Table 2. PIN CONFIGURATION
Pin#
Pin Name
4,3
PCLK, PCLK
I/O
Type
Function
Input
LVPECL
LVPECL Clock Inputs
2
CCLK
Input
LVCMOS
Alternative clock signal input
1
CLK_SEL
Input
LVCMOS
Clock input select
Input
LVCMOS
Clock output enable/disable
OE
Input
LVCMOS
Output enable/disable
(high–impedance tristate)
Q0 – Q11
Output
LVCMOS
Clock output
8,12,16,20,24,28,32
GND
Supply
Ground
7,10,14,18,22,26,30
VCC
Supply
VCC
5
CLK_STOP
6
31,29,27,25,23,21,19,17,15,13,11,9
Negative power supply (GND) for
I/O and core.
Positive power supply for I/O and
core. All VCC pins must be
connected to the positive power
supply for correct operation
Table 3. ABSOLUTE MAXIMUM RATINGS1
Symbol
Parameter
Min
Max
Unit
VCC
Supply Voltage
–0.3
3.9
V
VIN
DC Input Voltage
–0.3
VCC + 0.3
V
VOUT
DC Output Voltage
–0.3
VCC + 0.3
V
IIN
DC Input Current
±20
mA
IOUT
DC Output Current
±50
mA
TStor
Storage Temperature Range
125
°C
–65
Note: 1. These are stress ratings only and are not implied for functional use. Exposure to absolute maximum ratings for prolonged periods of time may affect
device reliability.
3.3V/2.5V LVCMOS 1:12 Clock Fanout Buffer
Notice: The information in this document is subject to change without notice.
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ASM2I99448
May 2005
rev 0.3
Table 4. GENERAL SPECIFICATIONS
Symbol
Characteristic
Min
Typ
Max
Unit
Condition
VTT
Output Termination Voltage
V
MM
ESD Protection (Machine Model)
200
V
HBM
ESD Protection (Human Body Model)
2000
V
LU
Latch–up Immunity
200
mA
CPD
Power Dissipation Capacitance
10
pF
Per Output
CIN
Input Capacitance
4.0
pF
Inputs
VCC÷2
Table 5. DC CHARACTERISTICS (VCC = 3.3V ± 5%, TA = –40°C to +85°C)
Symbol
Characteristic
Min
Typ
Max
Unit
Condition
VIH
Input HIGH Voltage
2.0
VCC + 0.3
V
LVCMOS
VIL
Input LOW Voltage
–0.3
0.8
V
LVCMOS
VPP
Peak–to–Peak Input Voltage
PCLK
250
mV
LVPECL
VCMR1
Common Mode Range
PCLK
1.1
VCC – 0.6
V
LVPECL
300
µA
VIN = VCC or GND
V
IOH = –24mA3
V
V
IOL = 24mA3
IOL = 12mA
2
IIN
Input Current
VOH
Output HIGH Voltage
VOL
Output LOW Voltage
ZOUT
ICCQ
4
Output Impedance
Maximum Quiescent Supply Current
2.4
0.55
0.30
17
Ώ
2.0
mA
All VCC Pins
Note: 1. VCMR (DC) is the crosspoint of the differential input signal. Functional operation is obtained when the crosspoint is within the VCMR range and the input
swing lies within the VPP (DC) specification.
2. Input pull-up / pull-down resistors influence input current.
3. The ASM2I99448 is capable of driving 50Ω transmission lines on the incident edge. Each output drives one 50Ω parallel terminated transmission line to
a termination voltage of VTT. Alternatively, the device drives up to two 50Ω series terminated transmission lines (for VCC=3.3V) or one 50Ω series
terminated transmission line (for VCC=2.5V).
4. ICCQ is the DC current consumption of the device with all outputs open and the input in its default state or open.
3.3V/2.5V LVCMOS 1:12 Clock Fanout Buffer
Notice: The information in this document is subject to change without notice.
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ASM2I99448
May 2005
rev 0.3
Table 6. AC CHARACTERISTICS (VCC = 3.3V ± 5%, TA = –40°C to +85°C)1
Symbol
fref
Characteristics
fMAX
Input Frequency
Maximum Output Frequency
VPP
Min
Peak-to-peak input voltage
PCLK
2
VCMR
Common Mode Range
PCLK
tP, REF
Reference Input Pulse Width
tr, tf
Max
Unit
0
0
Typ
350
350
MHz
MHz
400
1000
mV
LVPECL
1.3
VCC-0.8
V
LVPECL
1.4
nS
1.03
3.6
3.3
11
11
CCLK Input Rise/Fall Time
tPLH/HL
tPLH/HL
tPLZ, HZ
tPZL, LZ
tS
tH
1.6
1.3
CCLK to CLK_STOP
0.0
nS
PCLK to CLK_STOP
0.0
nS
CCLK to CLK_STOP
1.0
nS
PCLK to CLK_STOP
1.5
150
nS
pS
2.0
300
400
nS
pS
pS
55
1.0
%
nS
Output Disable Time
Output Enable Time
Setup time
Hold time
tsk(O)
Output-to-output Skew
tsk(PP)
tSK(P)
Device-to-device Skew
4
Output pulse skew
DCQ
tr, tf
Output Duty Cycle
Output Rise/Fall Time
nS
nS
nS
nS
nS
PCLK to any Q
CCLK to any Q
Propagation delay
PCLK or CCLK to any Q
Using CCLK
Using PCLK
fQ<170 MHz
45
0.1
Condition
50
0.8 to 2.0V
DCREF = 50%
0.55 to 2.4V
Note: 1. AC characteristics apply for parallel output termination of 50Ω to VTT.
2. VCMR (AC) is the crosspoint of the differential input signal. Normal AC operation is obtained when the crosspoint is within the VCMR range and the input
swing lies within the VPP (AC) specification. Violation of VCMR or VPP impacts tPLH/HL and tSK(PP).
3. Violation of the 1.0 nS maximum input rise and fall time limit will affect the device propagation delay, device-to-device skew, reference input pulse
width, output duty cycle and maximum frequency specifications.
4. Output pulse skew is the absolute difference of the propagation delay times: | tpLH - tpHL |.
Table 7. DC CHARACTERISTICS (VCC = 2.5V ± 5%, TA = –40°C to +85°C)
Symbol
VIH
VIL
Characteristics
Min
Input high voltage
Input low voltage
VPP
1
VCMR
IIN
Typ
1.7
-0.3
Peak-to-peak input voltage
PCLK
250
Common Mode Range
PCLK
1.0
2
Input current
VOH
Output High Voltage
VOL
Output Low Voltage
ZOUT
ICCQ4
Output impedance
Maximum Quiescent Supply Current
Max
Unit
VCC + 0.3
0.7
V
LVCMOS
V
LVCMOS
mV
LVPECL
VCC-0.7
V
300
µA
Condition
V
LVPECL
VIN=GND or
VIN=VCC
IOH= -15 mA3
0.6
V
IOL= 15 mA3
2.0
Ω
mA
All VCC Pins
1.8
19
Note: 1. VCMR (DC) is the crosspoint of the differential input signal. Functional operation is obtained when the crosspoint is within the VCMR
range and the input swing lies within the VPP (DC) specification.
2. Input pull-up / pull-down resistors influence input current.
3. The ASM2I99448 is capable of driving 50Ω transmission lines on the incident edge. Each output drives one 50Ω parallel terminated
transmission line to a termination voltage of VTT. Alternatively, the device drives one 50Ω series terminated transmission lines at VCC=2.5V.
4. ICCQ is the DC current consumption of the device with all outputs open and the input in its default state or open.
3.3V/2.5V LVCMOS 1:12 Clock Fanout Buffer
Notice: The information in this document is subject to change without notice.
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ASM2I99448
May 2005
rev 0.3
Table 8. AC CHARACTERISTICS (VCC = 2.5V ± 5%, TA = –40°C to +85°C)1
Symbol
fref
Characteristics
Min
Typ
Max
Unit
Input Frequency
0
350
MHz
fMAX
Maximum Output Frequency
0
350
MHz
VPP
Condition
Peak-to-peak input voltage
PCLK
400
1000
mV
LVPECL
VCMR2
Common Mode Range
PCLK
1.2
VCC-0.8
V
LVPECL
tP, REF
Reference Input Pulse Width
tr, tf
tPLH/HL
tPLH/HL
tPLZ, HZ
tPZL, LZ
tS
CCLK Input Rise/Fall Time
Propagation delay
1.4
PCLK to any Q
CCLK to any Q
CCLK to CLK_STOP
Setup time
CCLK to CLK_STOP
Hold time
PCLK to CLK_STOP
tsk(O)
tsk(PP)
Output-to-output Skew
Device-to-device Skew
4
Output pulse skew
PCLK or CCLK to any Q
DCQ
Output Duty Cycle
fQ< 350 MHz and using CLK
fQ<200 MHz and using PCLK
tr, tf
Output Rise/Fall Time
tSK(p)
1.03
4.2
4.4
11
11
1.5
1.7
Output Disable Time
Output Enable Time
PCLK to CLK_STOP
tH
nS
nS
nS
nS
nS
nS
0.0
nS
0.0
nS
1.0
nS
1.5
nS
Using CCLK Using PCLK
45
45
50
50
0.1
0.8 to 2.0V
150
2.7
pS
nS
200
300
pS
pS
55
55
%
%
DCREF = 50%
1.0
nS
0.6 to 1.8V
Note: 1. AC characteristics apply for parallel output termination of 50Ω to VTT.
2. VCMR (AC) is the crosspoint of the differential input signal. Normal AC operation is obtained when the crosspoint is within the VCMR
range and the input swing lies within the VPP (AC) specification. Violation of VCMR or VPP impacts tPLH/HL and tSK(PP).
3. Violation of the 1.0nS maximum input rise and fall time limit will affect the device propagation delay, device-to-device skew, reference
input pulse width, output duty cycle and maximum frequency specifications.
4. Output pulse skew is the absolute difference of the propagation delay times: | tpLH - tpHL |.
3.3V/2.5V LVCMOS 1:12 Clock Fanout Buffer
Notice: The information in this document is subject to change without notice.
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ASM2I99448
May 2005
rev 0.3
APPLICATIONS INFORMATION
The waveform plots in Figure 3 “Single versus Dual Line
Termination Waveforms” show the simulation results of
an output driving a single line versus two lines. In both
CCLK or
PCLK
CLK _ STOP
3.0
Q0 to Q11
Timing Diagram
Figure 1. Output Clock Stop (CLK_STOP)
Driving Transmission Lines
The ASM2I99448 clock driver was designed to drive high
speed signals in a terminated transmission line
environment. To provide the optimum flexibility to the
user, the output drivers were designed to exhibit the
lowest impedance possible. With an output impedance of
17Ω (VCC=3.3V), the outputs can drive either parallel or
series terminated transmission lines. In most high
performance clock networks, point–to–point distribution of
signals is the method of choice. In a point–to–point
scheme, either series terminated or parallel terminated
transmission lines can be used. The parallel technique
terminates the signal at the end of the line with a 50Ω
resistance to VCC÷2.
ASM2I99448
OUTPUT BUFFER
17Ω
ASM2I99448
OUTPUT BUFFER
Z0=50Ω
RS=33Ω
Z0=50Ω
RS=33Ω
17Ω
RS=33Ω
Z0=50Ω
Figure 2. Single versus Dual Transmission
Lines
This technique draws a fairly high level of DC current and
thus only a single terminated line can be driven by each
output of the ASM2I99448 clock driver. For the series
terminated case, however, there is no DC current draw;
thus, the outputs can drive multiple series terminated
lines. Figure 2 “Single versus Dual Transmission Lines”
illustrates an output driving a single series terminated line
versus two series terminated lines in parallel. When taken
to its extreme, the fanout of the ASM2I99448 clock driver
is effectively doubled due to its capability to drive multiple
lines at VCC=3.3V.
VOLTAGE (V)
2.5
OutA
tD = 3.8956
OutB
tD = 3.9386
2.0
In
1.5
1.0
0.5
0
2
4
6
8
10
12
14
TIME (nS)
Figure 3 . Single versus Dual Line Termination
Waveforms
cases, the drive capability of the ASM2I99448 output
buffer is more than sufficient to drive 50Ω transmission
lines on the incident edge. Note from the delay
measurements in the simulations a delta of only 43pS
exists between the two differently loaded outputs. This
suggests that the dual line driving need not be used
exclusively to maintain the tight output–to–output skew of
the ASM2I99448. The output waveform in Figure 3
“Single versus Dual Line Termination Waveforms” shows
a step in the waveform; this step is caused by the
impedance mismatch seen looking into the driver. The
parallel combination of the 33Ω series resistor plus the
output impedance does not match the parallel
combination of the line impedances. The voltage wave
launched down the two lines will equal:
VL = VS ( Z0 ÷ (RS+R0 +Z0))
Z0 = 50Ω|| 50Ω
RS = 33Ω|| 33Ω
R0 = 17Ω
VL = 3.0 ( 25 ÷ (16.5+17+25)
= 1.28V
At the load end the voltage will double, due to the near
unity reflection coefficient, to 2.5V. It will then increment
towards the quiescent 3.0V in steps separated by one
round trip delay (in this case 4.0nS).
Since this step is well above the threshold region it will
not cause any false clock triggering; however, designers
may be uncomfortable with unwanted reflections on the
line. To better match the impedances when driving
3.3V/2.5V LVCMOS 1:12 Clock Fanout Buffer
Notice: The information in this document is subject to change without notice.
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ASM2I99448
May 2005
rev 0.3
multiple lines, the situation in Figure 4 “Optimized Dual
Line Termination” should be used. In this case, the series
terminating resistors are reduced such that when the
parallel combination is added to the output buffer
impedance the line impedance is perfectly matched.
ASM2I99448
OUTPUT BUFFER
RS=16Ω
17Ω
RS=16Ω
Increased power consumption will increase the die
junction temperature and impact the device reliability
(MTBF). According to the system-defined tolerable
MTBF, the die junction temperature of the ASM2I99448
needs to be controlled and the thermal impedance of the
board/package should be optimized.The power dissipated
in the ASM2I99448 is represented in equation 1.
Z0=50Ω
Where ICCQ is the static current consumption of the
ASM2I99448, CPD is the power dissipation capacitance
per output, (Μ)ΣCL represents the external capacitive
output load, N is the number of active outputs (N is
always 12 in case of the ASM2I99448). The ASM2I99448
supports driving transmission lines to maintain high signal
integrity and tight timing parameters. Any transmission
line will hide the lumped capacitive load at the end of the
board trace, therefore, ΣCL is zero for controlled
transmission line systems and can be eliminated from
equation 1. Using parallel termination output termination
results in equation 2 for power dissipation.
Z0=50Ω
17Ω + 16Ω || 16Ω = 50Ω || 50Ω
25Ω = 25Ω
Figure 4. Optimized Dual Line Termination
Power Consumption of the ASM299448 and
Thermal Management
The ASM2I99448 AC specification is guaranteed for the
entire operating frequency range up to 350MHz. The
ASM2I99448 power consumption and the associated
long-term reliability may decrease the maximum
frequency limit, depending on operating conditions such
as clock frequency, supply voltage, output loading,
ambient temperature, vertical convection and thermal
conductivity of package and board. This section
describes the impact of these parameters on the junction
temperature and gives a guideline to estimate the
ASM2I99448 die junction temperature and the associated
device reliability.
In equation 2, P stands for the number of outputs with a
parallel or thevenin termination, VOL, IOL, VOH and IOH
are a function of the output termination technique and
DCQ is the clock signal duty cycle. If transmission lines
are used ΣCL is zero in equation 2 and can be
eliminated. In general, the use of controlled transmission
line techniques eliminates the impact of the lumped
capacitive loads at the end lines and greatly reduces the
power dissipation of the device. Equation 3 describes the
die junction temperature TJ as a function of the power
consumption.
Table 9. Die junction temperature and MTBF
Junction temperature (°C)
MTBF (Years)
100
20.4
110
9.1
120
130
4.2
2.0
Where Rthja is the thermal impedance of the package
(junction to ambient) and TA is the ambient temperature.
According to Table 9, the junction temperature can be
used to estimate the long-term device reliability. Further,
combining equation 1 and equation 2 results in a
maximum operating frequency for the ASM2I99448 in a
series terminated transmission line system, equation 4.



PTOT =  I CCQ + VCC ⋅ f CLOCK ⋅  N ⋅ C PD + ∑ C L  ⋅ VCC
M






PTOT = VCC ⋅  I CCQ + VCC ⋅ f CLOCK ⋅  N ⋅ C PD + ∑ C L  + ∑ DC Q ⋅ I OH (VCC − VOH ) + (1 − DC Q ) ⋅ I OL ⋅ VOL
M

 P

T J = T A + PTOT ⋅ Rthja
[
f CLOCKMAX =
C PD
1
2
⋅ N ⋅ VCC
T

− TA
⋅  JMAX
− (I CCQ ⋅ VCC )
 Rthja

3.3V/2.5V LVCMOS 1:12 Clock Fanout Buffer
Notice: The information in this document is subject to change without notice.
Equation 1
]
Equation 2
Equation 3
Equation 4
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ASM2I99448
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rev 0.3
TJ, MAX should be selected according to the MTBF
system requirements and Table 9. Rthja can be derived
from Table 10. The Rthja represent data based on 1S2P
boards, using 2S2P boards will result in lower thermal
impedance than indicated below.
If the calculated maximum frequency is below 350 MHz, it
becomes the upper clock speed limit for the given
application conditions. The following eight derating charts
describe the safe frequency operation range for the
ASM2I99448. The charts were calculated for a maximum
tolerable die junction temperature of 110°C (120°C),
corresponding to an estimated MTBF of 9.1 years
(4 years), a supply voltage of 3.3V and series terminated
transmission line or capacitive loading. Depending on a
given set of these operating conditions and the available
device convection a decision on the maximum operating
frequency can be made.
Table 10. Thermal package impedance of the
32LQFP
Convection,
Rthja (1P2S
Rthja (2P2S
board), °C/W
board), °C/W
LFPM
Still air
100 lfpm
200 lfpm
300 lfpm
400 lfpm
500 lfpm
86
76
71
68
66
60
61
56
54
53
52
49
fMAX (AC)
300
TA = 85°C
250
200
150
Safe operation
100
300
TA = 75°C
250
200
TA = 85°C
150
100
Safe operation
50
50
0
0
500
400
300
200
100
Convection Ifpm
500
0
fMAX (AC)
350
250
200
150
Safe operation
100
300
200
100
Convection Ifpm
0
fMAX (AC)
350
Operating frequency (MHz)
300
400
Figure 6. Maximum ASM2I99448 frequency
VCC= 3.3V, MRBF 9.1 years, 4pF load per line,
2s2p board
Figure 5. Maximum ASM2I99448 frequency VCC =
3.3V, MTBF 9.1 years, driving series terminated
transmission lines, 2s2p board
Operating frequency (MHz)
fMAX (AC)
350
Operating frequency (MHz)
Operating frequency (MHz)
350
50
300
TA = 85°C
250
200
150
Safe operation
100
50
0
0
500
400
300
200
100
Convection Ifpm
0
Figure 7. No maximum frequency limitation for
VCC = 3.3V, MTBF 4 years, driving series terminated
transmission lines, 2s2p board
500
400
300
200
100
Convection Ifpm
0
Figure 8. Maximum ASM2I99448
frequency VCC = 3.3V, MRBF 4 years, 4pF
load per line, 2s2p board
3.3V/2.5V LVCMOS 1:12 Clock Fanout Buffer
Notice: The information in this document is subject to change without notice.
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ASM2I99448
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rev 0.3
The Following Figures illustrate the Measurement Reference for the ASM2I99448 Clock Driver Circuit
Z0=50Ω
Z0=50Ω
Pulse
Generator
Z=50Ω
RT=50Ω
RT=50Ω
VTT
TT
Figure 9. CCLK ASM2I99448 AC Test Reference for VCC = 3.3V and VCC
Z0=50Ω
Z0=50Ω
Differential
Pulse Generator
Z=50Ω
RT=50Ω
RT=50Ω
VTT
VTT
Figure 10. PCLK ASM2I99448 AC Test Reference
3.3V/2.5V LVCMOS 1:12 Clock Fanout Buffer
Notice: The information in this document is subject to change without notice.
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ASM2I99448
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rev 0.3
PCLK
VPP
PCLK
VCC
CCLK
VCMR
VCC ÷2
GND
VCC
VCC ÷2
QX
tP(LH)
VCC
QX
VCC ÷2
GND
tP(HL)
tP(LH)
Figure 11. Propagation Delay (tPD) Test Reference
GND
tP(HL)
Figure 12. Propagation Delay (tPD) Test Reference
VCC
VCC ÷2
VCC
CCLK
VCC ÷2
GND
GND
VCC
VCC ÷2
tSK(LH)
tSK(HL)
GND
VCC
QX
VCC ÷2
tP(LH)
The pin-to-pin skew is defined as the worst case
difference in propagation between any similar delay path
within a single device
GND
tP(HL)
tSK(P) =| tPHL - tPHL |
Figure 14. Output Pulse Skew (tSK(P) Test Reference
Figure 13. Output–to–Output Skew tSK(LH, HL)
VCC
VCC ÷2
VCC = 3.3V VCC = 2.5V
GND
2.4
0.5
tP
tR
tF
T0
DC (tP ÷T0 Χ 100%)
1.8V
0.6V
Figure 16. Output Transition Time Test Reference
The time from the output controlled edge to the
non-controlled edge, divided by the time output
controlled edge, expressed as a percentage.
Figure 15. Output Duty Cycle (DC)
VCC
CCLK
PCLK
VCC ÷2
GND
TJIT(CC) = |TN -TN + 1|
TN
TN + 1
VCC
CLK_STOP
The variation in cycle time of a single between adjacent
cycles, over a random sample of adjacent cycle pairs
VCC ÷2
GND
tS
tH
Figure 17. Cycle–to–Cycle Jitter Reference
Figure 18. Setup and Hold Time (tS, tH) Test
3.3V/2.5V LVCMOS 1:12 Clock Fanout Buffer
Notice: The information in this document is subject to change without notice.
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ASM2I99448
May 2005
rev 0.3
Package Information
32-lead TQFP Package
SECTION A-A
Symbol
Dimensions
Inches
Millimeters
Min
Max
Min
Max
A
….
0.0472
…
1.2
A1
0.0020
0.0059
0.05
0.15
A2
0.0374
0.0413
0.95
1.05
D
0.3465
0.3622
8.8
9.2
D1
0.2717
0.2795
6.9
7.1
E
0.3465
0.3622
8.8
9.2
E1
0.2717
0.2795
6.9
7.1
L
0.0177
0.0295
0.45
0.75
L1
0.03937 REF
1.00 REF
T
0.0035
0.0079
0.09
0.2
T1
0.0038
0.0062
0.097
0.157
b
0.0118
0.0177
0.30
0.45
b1
0.0118
0.0157
0.30
0.40
R0
0.0031
0.0079
0.08
0.2
a
0°
7°
0°
7°
e
0.031 BASE
0.8 BASE
3.3V/2.5V LVCMOS 1:12 Clock Fanout Buffer
Notice: The information in this document is subject to change without notice.
12 of 15
ASM2I99448
May 2005
rev 0.3
32-lead LQFP Package
SECTION A-A
Dimensions
Symbol
Inches
Min
Max
Millimeters
Min
Max
A
….
0.0630
…
1.6
A1
0.0020
0.0059
0.05
0.15
A2
0.0531
0.0571
1.35
1.45
D
0.3465
0.3622
8.8
9.2
D1
0.2717
0.2795
6.9
7.1
E
0.3465
0.3622
8.8
9.2
E1
0.2717
0.2795
6.9
7.1
L
0.0177
0.0295
0.45
0.75
L1
0.03937 REF
1.00 REF
T
0.0035
0.0079
0.09
0.2
T1
0.0038
0.0062
0.097
0.157
b
0.0118
0.0177
0.30
0.45
b1
0.0118
0.0157
0.30
0.40
R0
0.0031
0.0079
0.08
0.20
e
a
0.031 BASE
0°
7°
0.8 BASE
0°
7°
3.3V/2.5V LVCMOS 1:12 Clock Fanout Buffer
Notice: The information in this document is subject to change without notice.
13 of 15
ASM2I99448
May 2005
rev 0.3
Ordering Information
Part Number
Marking
Package Type
Operating Range
ASM2I99448-32-LT
ASM2I99448L
32-pin LQFP, Tray
Industrial
ASM2I99448-32-LR
ASM2I99448L
32-pin LQFP –Tape and Reel
Industrial
ASM2I99448G-32-LT
ASM2I99448GL
32-pin LQFP, Tray, Green
Industrial
ASM2I99448G-32-LR
ASM2I99448GL
32-pin LQFP –Tape and Reel, Green
Industrial
ASM2I99448-32-ET
ASM2I99448E
32-pin TQFP, Tray
Industrial
ASM2I99448-32-ER
ASM2I99448E
32-pin TQFP –Tape and Reel
Industrial
ASM2I99448G-32-ET
ASM2I99448GE
32-pin TQFP, Tray, Green
Industrial
ASM2I99448G-32-ER
ASM2I99448GE
32-pin TQFP –Tape and Reel, Green
Industrial
Device Ordering Information
A S M 2 I 9 9 4 4 8 G - 3 2 - L R
R = Tape & reel, T = Tube or Tray
O = SOT
S = SOIC
T = TSSOP
A = SSOP
V = TVSOP
B = BGA
Q = QFN
U = MSOP
E = TQFP
L = LQFP
U = MSOP
P = PDIP
D = QSOP
X = SC-70
DEVICE PIN COUNT
F = LEAD FREE AND RoHS COMPLIANT PART
G = GREEN PACKAGE
PART NUMBER
X= Automotive
I= Industrial
P or n/c = Commercial
(-40C to +125C) (-40C to +85C)
(0C to +70C)
1 = Reserved
2 = Non PLL based
3 = EMI Reduction
4 = DDR support products
5 = STD Zero Delay Buffer
6 = Power Management
7 = Power Management
8 = Power Management
9 = Hi Performance
0 = Reserved
ALLIANCE SEMICONDUCTOR MIXED SIGNAL PRODUCT
Licensed under US patent #5,488,627, #6,646,463 and #5,631,920.
3.3V/2.5V LVCMOS 1:12 Clock Fanout Buffer
Notice: The information in this document is subject to change without notice.
14 of 15
ASM2I99448
May 2005
rev 0.3
Alliance Semiconductor Corporation
2575, Augustine Drive,
Santa Clara, CA 95054
Tel# 408-855-4900
Fax: 408-855-4999
www.alsc.com
Copyright © Alliance Semiconductor
All Rights Reserved
Part Number: ASM2I99448
Document Version: 0.3
Note: This product utilizes US Patent # 6,646,463 Impedance Emulator Patent issued to Alliance Semiconductor, dated 11-11-2003
© Copyright 2003 Alliance Semiconductor Corporation. All rights reserved. Our three-point logo, our name and Intelliwatt are
trademarks or registered trademarks of Alliance. All other brand and product names may be the trademarks of their
respective companies. Alliance reserves the right to make changes to this document and its products at any time without
notice. Alliance assumes no responsibility for any errors that may appear in this document. The data contained herein
represents Alliance's best data and/or estimates at the time of issuance. Alliance reserves the right to change or correct this
data at any time, without notice. If the product described herein is under development, significant changes to these
specifications are possible. The information in this product data sheet is intended to be general descriptive information for
potential customers and users, and is not intended to operate as, or provide, any guarantee or warrantee to any user or
customer. Alliance does not assume any responsibility or liability arising out of the application or use of any product
described herein, and disclaims any express or implied warranties related to the sale and/or use of Alliance products
including liability or warranties related to fitness for a particular purpose, merchantability, or infringement of any intellectual
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assumes all risk of such use and agrees to indemnify Alliance against all claims arising from such use.
3.3V/2.5V LVCMOS 1:12 Clock Fanout Buffer
Notice: The information in this document is subject to change without notice.
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