General
7.5.2 Thermal attributes
This section provides information about operating temperature range, power dissipation,
and package thermal resistance. Power dissipation on I/O pins is usually small compared
to the power dissipation in on-chip logic and voltage regulator circuits, and it is user-
determined rather than being controlled by the MCU design. To account for PI/O in power
calculations, determine the difference between actual pin voltage and VSS or VDD and
multiply by the pin current for each I/O pin. Except in cases of unusually high pin current
(heavy loads), the difference between pin voltage and VSS or VDD is very small.
See Thermal Design Considerations for more detail on thermal design considerations.
Board type
Symbol
Description
80 LQFP
100 LQFP
Unit
Notes
Single-layer
(1s)
RθJA
Thermal
resistance,
junction to
55
57
°C/W
1, 2
ambient (natural
convection)
Four-layer
(2s2p)
RθJA
Thermal
resistance,
junction to
ambient (natural
convection)
40
44
34
24
44
47
38
28
°C/W
°C/W
°C/W
°C/W
1, 3
1,3
1,3
4
Single-layer
(1s)
RθJMA
RθJMA
RθJB
Thermal
resistance,
junction to
ambient (200 ft./
min. air speed)
Four-layer
(2s2p)
Thermal
resistance,
junction to
ambient (200 ft./
min. air speed)
—
Thermal
resistance,
junction to
board
—
—
RθJC
Thermal
resistance,
junction to case
12
3
15
3
°C/W
°C/W
5
6
ΨJT
Thermal
characterization
parameter,
junction to
package top
outside center
(natural
convection)
MC56F8458x Advance Information Data Sheet, Rev. 2, 06/2012.
Freescale Semiconductor, Inc.
33
Preliminary
General Business Information
FREESCALE [ Freescale ]
