Electrical Characteristics

MPC5510 Microcontroller Family Data Sheet, Rev. 2

Preliminary—Subject to Change Without Notice

Freescale Semiconductor

21

2.2

Thermal Characteristics

2.2.1

General Notes for Specifications at Maximum Junction Temperature

An estimation of the chip junction temperature, T

J

, can be obtained from the equation:

Eqn. 1

where:

Eqn. 2

Eqn. 3

Eqn. 4

The supplied thermal resistances are provided based on JEDEC JESD51 series of standards to provide consistent values for

estimations and comparisons. The difference between the values determined on the single-layer (1s) board and on the four-layer

board with two signal layers and a power and a ground plane (2s2p) clearly demonstrate that the effective thermal resistance of

Table 4. Thermal Characteristics

Num

Characteristic

Symbol Unit

Value

208 MAPBGA

176 LQFP

144 LQFP

1

Natural Convection

(Single layer board)

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

resistance.

°C/W

45

38

43

2

Junction to Ambient 1, 3

Natural Convection

(Four layer board 2s2p)

°C/W

28

31

34

3

Junction to Ambient 1, 3

(@200 ft./min., Single layer board)

—

30

34

4

Junction to Ambient 1, 3

(@200 ft./min., Four layer board 2s2p)

—

25

28

5

the top surface of the board near the package.

°C/W

—

20

22

6

(MIL SPEC-883 Method 1012.1) with the cold plate temperature used for the case temperature.

°C/W

—

6

7

7

Natural Convection

temperature per JEDEC JESD51-2.

Ψ

JT

°C/W

—

2

2