MPC9448AC Integrated Device Technology (Idt), MPC9448AC Datasheet - Page 7

• Manufacturer Part Number: MPC9448AC
• Description: Clock Driver 2-IN LVCMOS 32-Pin TQFP Tray
• Manufacturer: Integrated Device Technology (Idt)

Specifications of MPC9448AC

• Package: 32TQFP
• Configuration: 1 x 2:1
• Input Signal Type: LVCMOS/LVPECL
• Maximum Output Frequency: 350 MHz
• Maximum Quiescent Current: 2 mA
• Operating Supply Voltage: 2.5|3.3 V

IDT™ / ICS™ LVCMOS 1:12 CLOCK FANOUT BUFFER
MPC9448
3.3V/2.5V LVCMOS 1:12 CLOCK FANOUT BUFFER
cause any false clock triggering; however, designers may be
uncomfortable with unwanted reflections on the line. To better
match the impedances when driving multiple lines, the
situation in
terminating resistors are reduced such that when the parallel
combination is added to the output buffer impedance, the line
impedance is perfectly matched.
Power Consumption of the MPC9448 and
Thermal Management
entire operating frequency range up to 350 MHz. The
MPC9448 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
MPC9448 die junction temperature and the associated
device reliability. For a complete analysis of power
consumption as a function of operating conditions and
associated long term device reliability, please refer to the
Freescale application note AN1545. According the AN1545,
the long-term device reliability is a function of the die junction
temperature:
P
Since this step is well above the threshold region, it will not
The MPC9448 AC specification is guaranteed for the
TOT
Figure 6. Optimized Dual Line Termination
= V
MPC9448
Output
17Ω
Buffer
Figure 6
CC
17Ω + 16Ω || 16Ω = 50Ω || 50Ω
·
[
I
CCQ
should be used. In this case, the series
+ V
25Ω = 25Ω
R
R
S
S
CC
= 16Ω
= 16Ω
· f
f
CLOCK
CLOCK,MAX =
P
TOT
Z
Z
O
O
·
= 50Ω
= 50Ω
=
(
N · C
[
I
CCQ
C
PD
PD
+ V
+
· N · V
Σ
CC
M
T
1
J
C
= T
· f
L
2
CLOCK
)
CC
A
]
+ P
+
·
Σ
[
P
7
TOT
·
[
(
DC
Table 9. Die Junction Temperature and MTFB
junction temperature and impact the device reliability
(MTBF). According to the system-defined tolerable MTBF,
the die junction temperature of the MPC9448 needs to be
controlled, and the thermal impedance of the board/package
should be optimized. The power dissipated in the MPC9448
is represented in equation 1.
MPC9448, C
output.
load, and N is the number of active outputs (N is always 12 in
case of the MPC9448). The MPC9448 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,
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.
parallel or thevenin termination. V
function of the output termination technique, and DC
clock signal duty cycle. If transmission lines are used,
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 T
function of the power consumption.
(junction to ambient), and T
According to
to estimate the long-term device reliability. Further, combining
equation 1 and equation 2 results in a maximum operating
frequency for the MPC9448 in a series terminated
transmission line system, equation 4.
N · C
T
· R
j,MAX
Junction Temperature (°C)
Increased power consumption will increase the die
Where I
In equation 2, P stands for the number of outputs with a
Where R
Q
R
thja
· I
PD
thja
OH
– T
(Μ)Σ
+
· (V
Σ
M
A
CCQ
thja
C
PD
100
110
120
130
Figure
C
CC
L
– (I
L
is the thermal impedance of the package
is the static current consumption of the
)
is the power dissipation capacitance per
represents the external capacitive output
– V
]
CCQ
· V
9, the junction temperature can be used
OH
CC
· V
) + (1 – DC
CC
A
)
is the ambient temperature.
]
MPC9448
OL
Q
) · I
, I
OL
MTBF (Years)
OL
, V
· V
OH
20.4
9.1
4.2
2.0
OL
REV 6 JULY 11, 2006
and I
]
Equation 1
Equation 2
Equation 3
Equation 4
OH
J
Q
as a
Σ
is the
are a
C
Σ
L
C
is
L