MPC9443 Motorola, MPC9443 Datasheet - Page 9

• Manufacturer Part Number: MPC9443
• Description: 2.5V AND 3.3V LVCMOS CLOCK FANOUT BUFFER
• Manufacturer: Motorola

Power Consumption of the MPC9443 and Thermal
Management
entire operating frequency range up to 350 MHz. The
MPC9443 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 temperture, 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
MPC9443 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
application note AN1545. According the AN1545, the
long-term device reliability is a function of the die junction
temperature:
junction temperature and impact the device reliability
(MTBF). According to the system-defined tolerable MTBF, the
die junction temperature of the MPC9443 needs to be
controlled and the thermal impedance of the board/package
should be optimized. The power dissipated in the MPC9443
is represented in equation 1.
MPC9443, C PD is the power dissipation capacitance per
output,
load, N is the number of active outputs (N is always 16 in case
of the MPC9443). The MPC9443 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, C L 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.
P
TIMING SOLUTIONS
Table 13: Die junction temperature and MTBF
TOT
The MPC9443 AC specification is guaranteed for the
Increased power consumption will increase the die
Where I CCQ is the static current consumption of the
Junction temperature ( C)
+
V
CC
@
C L represents the external capacitive output
100
110
120
130
I
CCQ
f
)
CLOCK,MAX
P
TOT
V
CC
+
@
f
CLOCK
+
I
CCQ
C
PD
)
@
Freescale Semiconductor, Inc.
@
V
T
N
MTBF (Years)
N
1
For More Information On This Product,
CC
J
@
@
+
@
V
C
20.4
9.1
4.2
2.0
f
T
2
CC
PD
CLOCK
A
)
@
)
Go to: www.freescale.com
P
T
@
M
TOT
J,MAX
C
N
R
L
@
thja
@
*
R
C
thja
T
PD
)
A
)
*
9
P
M
DC
I
parallel or thevenin termination, V OL , I OL , V OH and I OH are a
function of the output termination technique and DC Q is the
clock signal duty cyle. If transmission lines are used C L 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 T J as a function of
the power consumption.
(junction to ambient) and T A is the ambient temperature.
According to Table 13, 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 MPC9443 in a series terminated
transmission line system.
requirements and Table 13. R thja can be derived from Table
14. The R thja represent data based on 1S2P boards, using
2S2P boards will result in a lower thermal impedance than
indicated below.
becomes the upper clock speed limit for the given application
conditions. The following eight derating charts describe the
safe frequency operation range for the MPC9443. 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.
CCQ
Table 14: Thermal package impedance of the 48ld LQFP
Convection, LFPM
C
In equation 2, P stands for the number of outputs with a
Where R thja is the thermal impedance of the package
T J,MAX should be selected according to the MTBF system
If the calculated maximum frequency is below 250 MHz, it
Q
L
@
@
V
I
100 lfpm
200 lfpm
300 lfpm
400 lfpm
500 lfpm
OH
Still air
CC
@
@
V
CC
V
CC
*
V
OH
)
R thja (1P2S
board), K/W
1
69
64
*
DC
Q
@
I
OL
@
V
R thja (2P2S
board), K/W
OL
MPC9443
Equation 1
MOTOROLA
53
50
Equation 3
Equation 4
Equation 2