MPC860DPZQ80D4 Freescale Semiconductor, MPC860DPZQ80D4 Datasheet - Page 12

• Manufacturer Part Number: MPC860DPZQ80D4
• Description: IC MPU POWERQUICC 80MHZ 357PBGA
• Manufacturer: Freescale Semiconductor

Specifications of MPC860DPZQ80D4

• Processor Type: MPC8xx PowerQUICC 32-Bit
• Speed: 80MHz
• Voltage: 3.3V
• Mounting Type: Surface Mount
• Package / Case: 357-PBGA
• Features: -

Thermal Calculation and Measurement
7
For the following discussions, P
drivers.
7.1
An estimation of the chip junction temperature, T
where:
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 T
7.2
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:
where:
R
affect the case-to-ambient thermal resistance, R
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
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
12
θJC
is device related and cannot be influenced by the user. The user adjusts the thermal environment to
Thermal Calculation and Measurement
T
R
P
R
R
R
A
D
θJA
θJA
θJC
θCA
Estimation with Junction-to-Ambient Thermal Resistance
Estimation with Junction-to-Case Thermal Resistance
Estimation with Junction-to-Board Thermal Resistance
= ambient temperature (ºC)
= power dissipation in package
= junction-to-case thermal resistance (ºC/W)
= package junction-to-ambient thermal resistance (ºC/W)
= junction-to-ambient thermal resistance (ºC/W)
= case-to-ambient thermal resistance (ºC/W)
T
R
J
θJA
= T
= R
A
+ (R
θJC
MPC860 PowerQUICC™ Family Hardware Specifications, Rev. 8
θJA
+ R
× P
θCA
D
= (V
D
)
DD
× I
DD
J
θCA
– T
) + PI/O, where PI/O is the power dissipation of the I/O
J
Figure
, in ºC can be obtained from the equation:
A
. For instance, the user can change the airflow around
) are possible.
2.
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