TS68040VR25A Atmel, TS68040VR25A Datasheet - Page 12

• Manufacturer Part Number: TS68040VR25A
• Description: IC MPU 32BIT 25MHZ 179PGA
• Manufacturer: Atmel

Specifications of TS68040VR25A

• Processor Type: 68000 32-Bit
• Speed: 25MHz
• Voltage: 5V
• Mounting Type: Surface Mount
• Package / Case: 179-PGA
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Features: -

Relationships Between
Thermal Resistances and
Temperatures
Thermal Management
Techniques
12
TS68040
To calculate the specific power dissipation of a specific design, the termination method
of each signal must be considered. For example, a signal output that is not connected
would not dissipate any additional power if it were configured in the large buffer rather
than the small buffer mode.
Since the maximum operating junction temperature has been specified to be 125°C.
The maximum case temperature, TC, in °C can be obtained from:
where:
T
T
P
In general, the ambient temperature, T
Where the thermal resistance from case to ambient,
parameter once a buffer output configuration has been determined. As seen from equa-
tion (3), reducing the case to ambient thermal resistance increases the maximum
operating ambient temperature. Therefore, by utilizing such methods as heat sinks and
ambient air cooling to minimize the
a lower junction temperature can be achieved.
However, an easier approach to thermal evaluation uses the following formulas:
or alternatively,
where:
This total thermal resistance of a package,
ductor junction to the package (case) surface (
ambient (
is user dependent. Thus, good thermal management by the user can significantly
reduce
ambient operating temperature.
To attain a reasonable maximum ambient operating temperature, a user must reduce
the barrier to heat flow from the semiconductor junction to the outside ambient (
The only way to accomplish this is to significantly reduce
management techniques as heat sinks and ambient air cooling.
The following paragraphs discuss some results of a thermal study of the TS68040
device without using any thermal management techniques; using only air-flow cooling,
using only a heat sink, and using heat sink combined with air-flow cooling.
C
J
JC
JA
JC
D
T
T
T
T
C
A
A
J
= thermal resistance from the junction to the ambient (
and
= T
= T
= T
= T
= Maximum case temperature
= Maximum junction temperature
= Maximum power dissipation of the device
= Thermal resistance between the junction of the die and the case
A
J
J
J
CA
- P
- P
- P
- P
CA
JC
. These components represent the barrier to heat flow from the semicon-
achieving either a lower semiconductor junction temperature or a higher
D
D
D
D
). Although
·
·
·
·
JC
JC
JA
JA
- P
D
·
JC
CA
is device related and cannot be influenced by the user,
CA
A
, a higher ambient operating temperature and/or
, in °C is a function of the following formula:
JA
, is a combination of its two components,
JC
) and from the case to the outside
(2)
(3)
(4)
(5)
CA
, is the only user-dependent
JC
CA
+
by applying such thermal
CA
).
2116A–HIREL–09/02
JA
CA
).