参数资料
型号: MPC855TZQ66D4
厂商: FREESCALE SEMICONDUCTOR INC
元件分类: 微控制器/微处理器
英文描述: 32-BIT, 66 MHz, RISC PROCESSOR, PBGA357
封装: 25 X 25 MM, 1.27 MM PITCH, PLASTIC, BGA-357
文件页数: 4/81页
文件大小: 1618K
代理商: MPC855TZQ66D4
MPC860 PowerQUICC Family Hardware Specifications, Rev. 8
12
Freescale Semiconductor
Thermal Calculation and Measurement
7
Thermal Calculation and Measurement
For the following discussions, PD = (VDD × IDD) + PI/O, where PI/O is the power dissipation of the I/O
drivers.
7.1
Estimation with Junction-to-Ambient Thermal Resistance
An estimation of the chip junction temperature, T
J, in C can be obtained from the equation:
TJ = TA + (RθJA × PD)
where:
TA = ambient temperature (C)
RθJA = package junction-to-ambient thermal resistance (C/W)
PD = power dissipation in package
The junction-to-ambient thermal resistance is an industry standard value which provides a quick and easy
estimation of thermal performance. However, the answer is only an estimate; test cases have demonstrated
that errors of a factor of two (in the quantity TJ – TA) are possible.
7.2
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:
RθJA = RθJC + RθCA
where:
RθJA = junction-to-ambient thermal resistance (C/W)
RθJC = junction-to-case thermal resistance (C/W)
RθCA = case-to-ambient thermal resistance (C/W)
RθJC is device related and cannot be influenced by the user. The user adjusts the thermal environment to
affect the case-to-ambient thermal resistance, RθCA. For instance, the user can change the airflow 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.
7.3
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; see Figure 2.
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相关代理商/技术参数
参数描述
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MPC855TZQP80D4 制造商:FREESCALE-SEMI 功能描述:
MPC8560ADS-BGA 功能描述:开发板和工具包 - 其他处理器 ADS BOARD - 8560 RoHS:否 制造商:Freescale Semiconductor 产品:Development Systems 工具用于评估:P3041 核心:e500mc 接口类型:I2C, SPI, USB 工作电源电压:
MPC8560ADS-BGAE 功能描述:开发板和工具包 - 其他处理器 ADS BOARD - 8560 RoHS:否 制造商:Freescale Semiconductor 产品:Development Systems 工具用于评估:P3041 核心:e500mc 接口类型:I2C, SPI, USB 工作电源电压:
MPC8560CPX667JB 功能描述:微处理器 - MPU PQ 3 8560-DRACOM RoHS:否 制造商:Atmel 处理器系列:SAMA5D31 核心:ARM Cortex A5 数据总线宽度:32 bit 最大时钟频率:536 MHz 程序存储器大小:32 KB 数据 RAM 大小:128 KB 接口类型:CAN, Ethernet, LIN, SPI,TWI, UART, USB 工作电源电压:1.8 V to 3.3 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:FBGA-324