ASM2I99447 is specifically designed to distribute LVCMOS
compatible clock signals up to a frequency of 350 MHz.
Each output provides a precise copy of the input signal with
a near zero skew. The outputs buffers support driving of
50Ω terminated transmission lines on the incident edge:
each is capable of driving either one parallel terminated or
two series terminated transmission lines.
Two selectable independent LVCMOS compatible clock
inputs are available, providing support of redundant clock
source systems. The ASM2I99447 CLK_STOP control is
synchronous to the falling edge of the input clock. It allows
the start and stop of the output clock signal only in a logic
low state, thus eliminating potential output runt pulses.
Applying the OE control will force the outputs into high
impedance mode.
All inputs have an internal pull–up or pull–down resistor
preventing unused and open inputs from floating. The
device supports a 2.5V or 3.3V power supply and an
ambient temperature range of –40°C to +85°C. The
Telecommunications and Computer Applications
Pin and Function Compatible to MPC947 and
MPC9447
Functional Description
The ASM2I99447 is a 3.3V or 2.5V compatible, 1:9 clock
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.
ASM2I99447
is
pin
and
function
compatible
but
performance enhanced to the MPC947 and MPC9447.
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.
May 2005
rev 0.3
Block Diagram
Pin Configuration
GND
GND
ASM2I99447
Q0
CCLK0
CCLK1
0
1
CLK
STOP
Q1
GND
Q2
V
CC
Q1
GND
Q5
Q0
Q5
Q6
V
CC
GND
30
31
32
1
2
3
4
5
6
7
8
11
10
9
Q8
V
CC
GND
25
26
27
28
29
24
23
22
21
20
19
18
17
16
15
14
GND
Q6
V
CC
Q7
GND
V
CC
CLK_SEL
Q2
Q3
SYNC
Q4
V
CC
CLK_STOP
GND
13
12
GND
V
CC
ASM2I99447
V
CC
OE
(All input resistors have a value of 25KΩ)
Q7
CLK_SEL
CLK_STOP
CCLK0
CCLK1
GND
V
CC
OE
Table 1. Function Table
Control
CLK_SEL
OE
CLK_STOP
Default
1
1
1
0
CLK0 input selected
Outputs disabled (high–impedance state)
1
Outputs synchronously stopped in logic low state
CLK1 input selected
Outputs enabled
Outputs active
Note: 1. OE = 0 will high–impedance tristate all outputs independent on CLK_STOP
Table 2. Pin Configuration
Pin #
3
4
2
5
6
11,13,15,19,21,23,26,28,30
1,8,9,12,16,17,20,24,25,29,32
7,10,14,18,22,27,31
Pin Name
CCLK0
CCLK1
CLK_SEL
CLK_STOP
OE
Q0 – Q8
GND
V
CC
I/O
Input
Input
Input
Input
Input
Output
Supply
Supply
Type
LVCMOS
LVCMOS
LVCMOS
LVCMOS
LVCMOS
LVCMOS
Ground
V
CC
Function
Clock signal input
Alternative clock signal input
Clock input select
Clock output enable/disable
Output enable/disable
(high–impedance tristate)
Clock outputs
Negative power supply (GND) for
Output and Core
Positive power supply for I/O and
core. All V
CC
pins must be connected
to the positive power supply for
correct operation
3.3V/2.5V 1:9 LVCMOS Clock Fanout Buffer
Notice: The information in this document is subject to change without notice.
V
CC
Q3
Q4
Q5
1
2 of 14
May 2005
rev 0.3
Table 3. General Specifications
Symbol
V
TT
MM
HBM
LU
C
PD
C
IN
ASM2I99447
Characteristics
Output termination voltage
ESD protection (Machine model)
ESD protection (Human body model)
Latch-up immunity
Power dissipation capacitance
Input capacitance
Min
200
2000
200
Typ
V
CC
÷2
Max
Unit
V
V
V
mA
Condition
10
4.0
pF
pF
Per output
Inputs
Table 4. Absolute Maximum Ratings
1
Symbol
V
CC
V
IN
V
OUT
I
IN
I
OUT
T
S
Characteristics
Supply Voltage
DC Input Voltage
DC Output Voltage
DC Input Current
DC Output Current
Storage temperature
Min
-0.3
-0.3
-0.3
Max
3.9
V
CC
+ 0.3
V
CC
+ 0.3
±20
±50
125
Unit
V
V
V
mA
mA
°C
Condition
-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.
Table 5. DC Characteristics
(V
CC
= 3.3V ± 5%, T
A
= 40°C to +85°C)
Symbol
V
IH
V
IL
V
OH
V
OL
Z
OUT
I
IN
I
CCQ
Characteristics
Input High Voltage
Input Low Voltage
Output High Voltage
Output Low Voltage
Output Impedance
Input Current
2
3
Min
2.0
–0.3
2.4
Typ
Max
V
CC
+ 0.3
0.8
0.55
0.30
Unit
V
V
V
V
V
W
mA
mA
Condition
LVCMOS
LVCMOS
I
OH
= -24 mA
1
I
OL
= 24 mA
I
OL
= 12 mA
V
IN
= V
CC
or GND
All V
CC
Pins
17
±300
2.0
Maximum Quiescent Supply Current
Note: 1.
The ASM2I99447 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 V
TT
. Alternatively, the device drives up to two 50Ω series terminated transmission lines (for V
CC
=3.3V).
2. Inputs have pull-down or pull-up resistors affecting the input current.
3. 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 1:9 LVCMOS Clock Fanout Buffer
Notice: The information in this document is subject to change without notice.
3 of 14
May 2005
rev 0.3
Table 6. AC Characteristics
(V
CC
= 3.3V ± 5%, T
A
= –40°C to +85°C)
1
Symbol
f
ref
f
max
f
P
,
REF
t
r
, t
f
t
PLH/HL
t
PLZ, HZ
t
PZL, ZH
t
S
t
H
t
sk(O)
t
sk(PP)
t
SK(P)
DCQ
t
r
, t
f
t
JIT(CC)
ASM2I99447
5Characteristics
Input Frequency
Output Frequency
Reference Input Pulse Width
CCLK0, CCLK1 Input Rise/Fall Time
Propagation Delay
Output Disable Time
Output Enable Time
Setup Time
CCLK0 or CCLK1 to CLK_STOP
3
3
Min
0
0
1.4
Typ
Max
350
350
1.0
2
Unit
MHz
MHz
nS
nS
nS
nS
nS
nS
nS
Condition
0.8 to 2.0V
CCLK0 or CCLK1 to any Q
1.3
3.3
11
11
0.0
1.0
150
2.0
300
55
1.0
TBD
Hold Time
CCLK0 or CCLK1 to CLK_STOP
Output-to-Output Skew
Device-to-Device Skew
Output Pulse Skew
4
Output Duty Cycle
MHz
Output Rise/Fall Time
Cycle-to-cycle jitter
pS
nS
pS
%
nS
pS
DC
REF
= 50%
0.55 to 2.4V
fQ<170
45
0.1
50
RMS (1σ)
Note: 1.
AC characteristics apply for parallel output termination of 50Ω to V
TT
.
2. 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.
3. Setup and hold times are referenced to the falling edge of the selected clock signal input.
4. Output pulse skew is the absolute difference of the propagation delay times: | t
PLH
- t
PHL
|.
Table 7. DC Characteristics
(V
CC
= 2.5V ± 5%, TA = –40°C to +85°C)
Symbol
V
IH
V
IL
V
OH
V
OL
Z
OUT
I
IN
I
CCQ
Characteristics
Input High Voltage
Input Low Voltage
Output High Voltage
Output Low Voltage
Output Impedance
Input Current
Maximum Quiescent Supply Current
3
2
Min
1.7
-0.3
1.8
Typ
Max
V
CC
+ 0.3
0.7
0.6
Unit
V
V
V
V
Ω
mA
mA
Condition
LVCMOS
LVCMOS
I
OH
=-15 mA
1
I
OL
= 15 mA
V
IN
= V
CC
or GND
All V
CC
Pins
19
±300
2.0
Note: 1.The ASM2I99447 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 V
TT
. Alternatively, the device drives one 50Ω
series terminated transmission lines per output (V
CC
=2.5V).
2. Inputs have pull-down or pull-up resistors affecting the input current.
3. 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 1:9 LVCMOS Clock Fanout Buffer
Notice: The information in this document is subject to change without notice.
4 of 14
May 2005
rev 0.3
Table 8. AC Characteristics
(V
CC
= 2.5V ± 5%, TA = –40°C to +85°C)
1
Symbol
f
ref
f
max
f
P,REF
t
r
, t
f
t
PLH/HL
t
PLZ, HZ
t
PZL, ZH
t
S
t
H
t
sk(O)
t
sk(PP)
t
SK(P)
DC
Q
t
r
, t
f
t
JIT(CC)
Input Frequency
Output frequency
Reference Input Pulse Width
CCLK0, CCLK1 Input Rise/Fall Time
Propagation Delay
Output Disable Time
Output Enable Time
Setup Time
CCLK0 or CCLK1 to CLK_STOP
3
3
ASM2I99447
Characteristics
Min
0
0
1.4
Typ
Max
350
350
1.0
2
Unit
MHz
MHz
nS
nS
nS
nS
nS
nS
nS
Condition
0.7 to 1.7V
CCLK0 or CCLK1 to any Q
1.7
4.4
11
11
0.0
1.0
150
2.7
200
55
1.0
Hold Time
CCLK0 or CCLK1 to CLK_STOP
Output-to-Output Skew
Device-to-Device Skew
Output Pulse Skew
4
Output Duty Cycle
pS
nS
pS
%
nS
pS
DC
REF
=50%
0.6 to 1.8V
f
Q
<350 MHz
Output Rise/Fall Time
Cycle-to-cycle jitter
RMS (1
σ)
45
0.1
50
TBD
Note:
1.
AC characteristics apply for parallel output termination of 50Ω to V
TT
.
2. 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.
3. Setup and hold times are referenced to the falling edge of the selected clock signal input.
4. Output pulse skew is the absolute difference of the propagation delay times: | t
PLH
- t
PHL
|.
3.3V/2.5V 1:9 LVCMOS Clock Fanout Buffer
Notice: The information in this document is subject to change without notice.
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