dsp56167 Freescale Semiconductor, Inc, dsp56167 Datasheet - Page 77

• Manufacturer Part Number: dsp56167
• Description: Advance Information 16-bit Digital Signal Processor
• Manufacturer: Freescale Semiconductor, Inc

HEAT DISSIPATION
MOTOROLA
Equation 1:
Equation 2:
An estimation of the chip junction temperature, T
equation:
Where:
T
R
P
Historically, thermal resistance has been expressed as the sum of a junction-to-case
thermal resistance and a case-to-ambient thermal resistance:
Where:
R
R
R
R
thermal environment to change the case-to-ambient thermal resistance, R
example, the user can change the air flow around the device, add a heat sink, change
the mounting arrangement on the printed circuit board, or otherwise change the
thermal dissipation capability of the area surrounding the device on a printed circuit
board. This model is most useful for ceramic packages with heat sinks; some 90% of
the heat flow is dissipated through the case to the heat sink and out to the ambient
environment. For ceramic packages, in situations where the heat flow is split between
a path to the case and an alternate path through the printed circuit board, analysis of
the device thermal performance may need the additional modeling capability of a
system level thermal simulation tool.
A
D
JA
JA
JC
CA
JC
= ambient temperature ˚C
= power dissipation in package
= package junction-to-case thermal resistance ˚C/W
is device-related and cannot be influenced by the user. The user controls the
= package junction-to-ambient thermal resistance ˚C/W
= package junction-to-ambient thermal resistance ˚C/W
= package case-to-ambient thermal resistance ˚C/W
DESIGN CONSIDERATIONS
T
R
J
JA
=
T
=
A
R
+
JC
P
D
+
R
SECTION
R
DSP56167/D, Rev. 1
CA
JA
J
, in C can be obtained from the
4
CA
. For
4-1