參數(shù)資料
型號(hào)： MPC8247CVRT
廠商： Motorola, Inc.
英文描述： MPC8272 PowerQUICC II Family Hardware Specifications
中文描述： MPC8272的PowerQUICC II系列硬件規(guī)格
文件頁(yè)數(shù)： 12/56頁(yè)
文件大小： 539K
代理商： MPC8247CVRT
12
MPC8272 PowerQUICC II Family Hardware Specifications
PRELIMINARY—SUBJECT TO CHANGE WITHOUT NOTICE
For More Information On This Product,
Go to: www.freescale.com
MOTOROLA
Thermal Characteristics
4.2
Estimation with Junction-to-Case Thermal Resistance
Historically, the thermal resistance has frequently been expressed as the sum of a junction-to-case thermal
resistance and a case-to-ambient thermal resistance:
R
θ
JA
= R
θ
JC
+ R
θ
CA
where:
R
θ
JA
= junction-to-ambient thermal resistance (oC/W)
R
θ
JC
= junction-to-case thermal resistance (oC/W)
R
θ
CA
= case-to-ambient thermal resistance (oC/W)
R
θ
JC
is device related and cannot be influenced by the user. The user adjusts the thermal environment to
affect the case-to-ambient thermal resistance, R
θ
CA
. For instance, the user can change the air flow around
the device, add a heat sink, change the mounting arrangement on the printed circuit board, or change the
thermal dissipation on the printed circuit board surrounding the device. This thermal model is most useful
for ceramic packages with heat sinks where some 90% of the heat flows through the case and the heat sink
to the ambient environment. For most packages, a better model is required.
4.3
Estimation with Junction-to-Board Thermal Resistance
A simple package thermal model which has demonstrated reasonable accuracy (about 20%) is a two-resistor
model consisting of a junction-to-board and a junction-to-case thermal resistance. The junction-to-case
thermal resistance covers the situation where a heat sink is used or where a substantial amount of heat is
dissipated from the top of the package. The junction-to-board thermal resistance describes the thermal
performance when most of the heat is conducted to the printed circuit board. It has been observed that the
thermal performance of most plastic packages, especially PBGA packages, is strongly dependent on the
board temperature.
If the board temperature is known, an estimate of the junction temperature in the environment can be made
using the following equation:
T
J
= T
B
+ (R
θ
JB
×
P
D
)
where:
R
θ
JB
= junction-to-board thermal resistance (oC/W)
T
B
= board temperature (oC)
P
D
= power dissipation in package
If the board temperature is known and the heat loss from the package case to the air can be ignored,
acceptable predictions of junction temperature can be made. For this method to work, the board and board
mounting must be similar to the test board used to determine the junction-to-board thermal resistance,
namely a 2s2p (board with a power and a ground plane) and by attaching the thermal balls to the ground
plane.
4.4
Estimation Using Simulation
When the board temperature is not known, a thermal simulation of the application is needed. The simple
two-resistor model can be used with the thermal simulation of the application, or a more accurate and
complex model of the package can be used in the thermal simulation.
F
Freescale Semiconductor, Inc.
n
.
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
MPC8247CVRTIEA 功能描述:微處理器 - MPU 400 MHz 760 MIPS RoHS:否 制造商:Atmel 處理器系列:SAMA5D31 核心:ARM Cortex A5 數(shù)據(jù)總線寬度:32 bit 最大時(shí)鐘頻率:536 MHz 程序存儲(chǔ)器大小:32 KB 數(shù)據(jù) RAM 大小:128 KB 接口類(lèi)型:CAN, Ethernet, LIN, SPI,TWI, UART, USB 工作電源電壓:1.8 V to 3.3 V 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:FBGA-324
MPC8247CZQ 制造商:MOTOROLA 制造商全稱(chēng):Motorola, Inc 功能描述:MPC8272 PowerQUICC II Family Hardware Specifications
MPC8247CZQB 制造商:FREESCALE 制造商全稱(chēng):Freescale Semiconductor, Inc 功能描述:PowerQUICC II⑩ Family Hardware Specifications
MPC8247CZQE 制造商:FREESCALE 制造商全稱(chēng):Freescale Semiconductor, Inc 功能描述:PowerQUICC II⑩ Family Hardware Specifications
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