dsp56001a Freescale Semiconductor, Inc, dsp56001a Datasheet - Page 79

• Manufacturer Part Number: dsp56001a
• Description: 24-bit Digital Signal Processor
• Manufacturer: Freescale Semiconductor, Inc

HEAT DISSIPATION
The average chip junction temperature, T
Where:
For most applications P
P
Solving equations (1) and (2) for K gives:
Where:
K can be determined from equation (2) by measuring P
this value of K, the values of P
for any value of T
components,
the package (case) surface (
related by the equation:
can be minimized by thermal management techniques such as heat sinks, ambient air cooling,
and thermal convection. Thus, good thermal management can significantly reduce
estimated, were derived using the procedure described in Motorola Reliability Report 7843,
“Thermal Resistance Measurement Method for MC68XX Microcomponent Devices”, and are
provided for design purposes only. Thermal measurements are complex and dependent on
procedure and setup. User-derived values for thermal resistance may differ.
MOTOROLA
D
JC
JA
and T
T
P
P
P
is device-related and cannot be influenced by the user. However,
approximately equals
A
D
INT
I/O
JA
= ambient temperature, C
= package thermal resistance, junction-to-ambient, C/W
= P
= power dissipation on input and output pins
J
Equation 1: T
Equation 2: P
Equation 3: K = P
Equation 4:
= I
(if P
K is a constant pertaining to the particular package
CC
INT
I/O
JC
+ P
V
is neglected) is:
and
CC
A
I/O
. The total thermal resistance of a package (
watt
Freescale Semiconductor, Inc.
CA
I/O
J
D
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—
JA
, representing the barrier to heat flow from the semiconductor junction to
= T
= K / (T
< P
=
chip internal power
JC
JC
D
A
) and from the case to the outside ambient (
. Values for thermal resistance presented in this document, unless
INT
D
+ (P
JC
(T
and T
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+
and P
J
A
D
+ 273)
+ 273) + P
DSP56001A/D, Rev. 1
CA
J
can be obtained by solving equations (1) and (2) iteratively
I/O
JA
)
can be neglected. An appropriate relationship between
J
, in C, can be obtained from:
D
JA
—
D
(at equilibrium) for a known T
user determined
JA
) can be separated into two
CA
is user-dependent and
CA
). These terms are
Heat Dissipation
DSP56001A
CA
A
so that
. Using
4-5