MC68LC040RC40A Freescale Semiconductor, MC68LC040RC40A Datasheet - Page 342

• Manufacturer Part Number: MC68LC040RC40A
• Description: IC MPU 32BIT 40MHZ 179-PGA
• Manufacturer: Freescale Semiconductor

Specifications of MC68LC040RC40A

• Processor Type: M680x0 32-Bit
• Speed: 40MHz
• Voltage: 5V
• Mounting Type: Surface Mount
• Package / Case: 179-PGA
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Features: -

In general, the ambient temperature (T
The thermal resistance from case to outside ambient (
parameter once a buffer output configuration has been determined. Reducing the case to
ambient thermal resistance increases the maximum operating ambient temperature.
Therefore, by utilizing methods such as heat sinks and ambient air cooling to minimize
achieved. However, an easier approach to thermal evaluation uses the following
equations:
where:
The total thermal resistance for a package (
junction to the package case surface (
the user cannot influence it,
user, such as heat sink and airflow, can significantly reduce
semiconductor junction temperature or a higher ambient operating temperature.
11.9 MC68040 THERMAL MANAGEMENT TECHNIQUES
To attain a reasonable maximum ambient operating temperature, the user must reduce
the barrier to heat flow from
cooling. The following paragraphs discuss thermal study results for the MC68040 that did
not use thermal management techniques, airflow cooling, heat sink, and heat sink
combined with airflow cooling.
The MC68040 power dissipation values given in this section represent the sum of the
power dissipated by the internal circuitry and the output buffers of the MC68040. The
termination network chosen by the system designer strongly influences this last
component of power. Values listed in this section for large buffer terminated entries reflect
a termination network as illustrated in Figure 11-8 and are consistent with specifications
for the MC68040. For additional termination schemes, refer to AN1051, Transmission Line
Effects in PCB Applications , or AN1061, Reflecting on Transmission Line Effects .
11-14
CA
JC
CA
JA
, a higher ambient operating temperature and/or a lower junction temperature can be
and
by applying thermal management techniques such as heat sinks and forced air
= Thermal Resistance from the Junction to the Ambient (
CA
. These components represent the barrier to heat flow from the semiconductor
T
A
Freescale Semiconductor, Inc.
= T
For More Information On This Product,
J
JA
T
– P
CA
A
. The only way to accomplish this is to significantly reduce
= T
M68040 USER’S MANUAL
D
is user dependent. Good thermal management by the
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J
– P
A
JA
JC
) in C is a function of the following equation:
D
) and
or
JA
JC
) is a combination of its two components,
CA
– P
T
J
. Although
= T
D
A
+ P
CA
CA
D
) is the only user-dependent
CA
JC
JC
JA
achieving either a lower
+
is package related and
CA
)
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