TS68040 ATMEL Corporation, TS68040 Datasheet - Page 12

• Manufacturer Part Number: TS68040
• Description: 32-bit Mpu, 25-33 MHZ
• Manufacturer: ATMEL Corporation

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Table 8 - Thermal parameters with forced air flow and no heat sink
By reviewing the maximum ambient operating temperatures, it can be seen that by using the all-small-buffer configuration
of the TS 68040 with a relatively small amount of air flow (100 LFM), a 0-70°C ambient operating temperature can be
achieved. However, depending on the output buffer configuration and available forced-air cooling, additional thermal mana-
gement techniques may be required.
Thermal characteristics with a heat sink
In choosing a heat sink the designer must consider many factors : heat sink size and composition, method of attachment,
and choice of a wet or dry connection. The following paragraphs discuss the relationship of these decisions to the thermal
performance of the design noticed during experimentation.
The heat sink size is one of the most significant parameters to consider in the selection of a heat sink. Obviously a larger
heat sink will provide better cooling. However, it is less obvious that the most benefit of the larger heat sink of the pin fin
type used in the experimentation would be at still air conditions. Under forced-air conditions as low as 100 LFM, the difference
between the
The particular heat sink used in our testing fit the perimeter package surface area available within the capacitor pads on
the TS 68040 (1.48"
sink base perimeter area was 1.24"
of Al alloy. The heat sink is shown in Figure 5 can be obtained through Thermalloy Inc. by referencing part number 2338B.
Air-flow velocity
Thermal Mgmt.
1 000 LFM
1 000 LFM
Technique
100 LFM
250 LFM
500 LFM
750 LFM
100 LFM
250 LFM
500 LFM
750 LFM
CA becoms very small (0.4°C/W or less). This difference continues to decrease as the forced air flow increases.
1.48") and showed a nice compromise between height and thermal performance needs. The heat
3 W
3 W
3 W
3 W
3 W
5 W
5 W
5 W
5 W
5 W
P D
Defined parameters
1.30" and its heigh was 0.49". It was a pin-fin-type (i.e. bed of nails) design composed
125°C
125°C
125°C
125°C
125°C
125°C
125°C
125°C
125°C
125°C
T J
Figure 5 : Heat sink example.
1°C/W
1°C/W
1°C/W
1°C/W
1°C/W
1°C/W
1°C/W
1°C/W
1°C/W
1°C/W
JC
Measured
11.7°C/W
11.7°C/W
8.9°C/W
8.5°C/W
8.3°C/W
8.9°C/W
8.5°C/W
8.3°C/W
10°C/W
10°C/W
JA
10.7°C/W
10.7°C/W
7.9°C/W
7.5°C/W
7.3°C/W
7.9°C/W
7.5°C/W
7.3°C/W
9°C/W
9°C/W
CA
Calculated
122°C
122°C
122°C
122°C
120°C
120°C
120°C
120°C
122°C
120°C
T C
100.1°C
89.9°C
98.3°C
99.5°C
66.5°C
80.5°C
82.5°C
83.5°C
95°C
75°C
T A