MPC8360CVVALDHA datasheet(92/102 Pages) FREESCALE

92 / 102 page

MPC8360E/MPC8358E PowerQUICC II Pro Processor Revision 2.x TBGA Silicon Hardware Specifications, Rev. 5

Freescale Semiconductor

Thermal Management Information

22.2

Thermal Management Information

For the following sections, PD = (VDD × IDD) + PI/O where PI/O is the power dissipation of the I/O drivers. See Table 6 for

typical power dissipations values.

22.2.1

Estimation of Junction Temperature with Junction-to-Ambient

Thermal Resistance

An estimation of the chip junction temperature, TJ, can be obtained from the equation:

TJ = TA + (RθJA × PD)

where:

TJ = junction temperature (° C)

TA = ambient temperature for the package (° C)

RθJA = junction-to-ambient thermal resistance (° C/W)

PD = power dissipation in the package (W)

The junction-to-ambient thermal resistance is an industry standard value that provides a quick and easy estimation of thermal

performance. As a general statement, the value obtained on a single-layer board is appropriate for a tightly packed

printed-circuit board. The value obtained on the board with the internal planes is usually appropriate if the board has low power

dissipation and the components are well separated. Test cases have demonstrated that errors of a factor of two (in the quantity

TJ – TA) are possible.

22.2.2

Estimation of Junction Temperature with Junction-to-Board

Thermal Resistance

The thermal performance of a device cannot be adequately predicted from the junction-to-ambient thermal resistance. The

thermal performance of any component is strongly dependent on the power dissipation of surrounding components.

Additionally, the ambient temperature varies widely within the application. For many natural convection and especially closed

box applications, the board temperature at the perimeter (edge) of the package is approximately the same as the local air

temperature near the device. Specifying the local ambient conditions explicitly as the board temperature provides a more precise

description of the local ambient conditions that determine the temperature of the device. At a known board temperature, the

junction temperature is estimated using the following equation:

Junction-to-package natural convection on top

ψJT

° C/W

Notes

1. Junction temperature is a function of die size, on-chip power dissipation, package thermal resistance, mounting site (board)

temperature, ambient temperature, airflow, power dissipation of other components on the board, and board thermal

resistance.

2. Per JEDEC JESD51-2 and SEMI G38-87 with the single layer board horizontal.

3. Per JEDEC JESD51-6 with the board horizontal. 1 m/sec is approximately equal to 200 linear feet per minute (LFM).

4. Thermal resistance between the die and the printed-circuit board per JEDEC JESD51-8. Board temperature is measured

on the top surface of the board near the package.

5. Thermal resistance between the die and the case top surface as measured by the cold plate method (MIL SPEC-883

Method 1012.1).

6. Thermal characterization parameter indicating the temperature difference between package top and the junction

temperature per JEDEC JESD51-2. When Greek letters are not available, the thermal characterization parameter is written

as Psi-JT.

Table 77. Package Thermal Characteristics for the TBGA Package (continued)

Characteristic

Symbol

Value

Unit

Notes

MPC8360CVVALDHA Datasheet(PDF) 92 Page - Freescale Semiconductor, Inc

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