MPC961C Просмотр технического описания (PDF) - Motorola => Freescale
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MPC961C Datasheet PDF : 12 Pages
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Freescale Semiconductor, Inc.
MPC961C
Table 8: Confidence Facter CF
CF
Probability of clock edge within the distribution
± 1s
0.68268948
± 2s
0.95449988
± 3s
0.99730007
± 4s
0.99993663
± 5s
0.99999943
± 6s
0.99999999
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
MPC961C 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:
The feedback trace delay is determined by the board
layout and can be used to fine-tune the effective delay
through each device. In the following example calculation a
I/O jitter confidence factor of 99.7% (± 3s) is assumed,
resulting in a worst case timing uncertainty from input to any
output of -275 ps to 315 ps relative to CCLK:
Table 9: Die junction temperature and MTBF
Junction temperature (°C)
MTBF (Years)
100
20.4
110
9.1
120
4.2
tSK(PP) =
@ @ [–80ps...120ps] + [–150ps...150ps] +
[(15ps –3)...(15ps 3)] + tPD, LINE(FB)
tSK(PP) = [–275ps...315ps] + tPD, LINE(FB)
Due to the frequency dependence of the I/O jitter,
Figure 8. “Max. I/O Jitter versus frequency” can be used for
a more precise timing performance analysis.
130
2.0
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 MPC961C needs to be
controlled and the thermal impedance of the board/package
should be optimized. The power dissipated in the MPC961C
is represented in equation 1.
Where ICCQ is the static current consumption of the
MPC961C, 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 27 in
case of the MPC961C). The MPC961C 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.
Figure 8. Max. I/O Jitter versus frequency
Power Consumption of the MPC961C and Thermal
Management
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 cyle. If transmission lines are used ΣCL is
The MPC961C AC specification is guaranteed for the
zero in equation 2 and can be eliminated. In general, the use
entire operating frequency range up to 200 MHz. The
of controlled transmission line techniques eliminates the
MPC961C power consumption and the associated long-term
impact of the lumped capacitive loads at the end lines and
reliability may decrease the maximum frequency limit,
greatly reduces the power dissipation of the device. Equation
depending on operating conditions such as clock frequency,
supply voltage, output loading, ambient temperature, vertical
3 describes the die junction temperature TJ as a function of
the power consumption.
+ƪ ) @ @ǒ @ )ȍ Ǔƫ@ PTOT
ICCQ VCC fCLOCK
N CPD
CL
M
VCC
Equation 1
+ @ƪ ) @ @ǒ @ )ȍ Ǔƫ)ȍƪ @ @ǒ * Ǔ)ǒ * Ǔ@ @ ƫ PTOT VCC
ICCQ VCC fCLOCK
N CPD
CL
DCQ IOH VCC VOH 1 DCQ IOL VOL Equation 2
M
P
+ ) @ TJ TA PTOT Rthja
+ @ @ @ ƪ * * ǒ @ Ǔƫ fCLOCK,MAX
1
CPD N V2CC
TJ,MAX TA
Rthja
ICCQ VCC
Equation 3
Equation 4
TIMING SOLUTIONS
DL207 — Rev 0
For More Informa7tion On This Product,
Go to: www.freescale.com
MOTOROLA
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