TS68040 datasheet(14/49 Pages) ATMEL

14 / 49 page

TS68040

2116A–HIREL–09/02

By reviewing the maximum ambient operating temperatures, it can be seen that by

using the all-small-buffer configuration of the TS68040 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 management 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 follow-

ing 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 exper-

imentation would be at still air conditions. Under forced-air conditions as low as 100

LFM, the difference between the

ΦCA becomes very small (0.4°C/W or less). This differ-

ence continues to decrease as the forced air flow increases. The particular heat sink

used in our testing fit the perimeter package surface area available within the capacitor

pads on the TS68040 (1.48" x 1.48") and showed a nice compromise between height

and thermal performance needs. The heat sink base perimeter area was 1.24" x 1.30"

and its height was 0.49". It was a pin-fin-type (i.e. bed of nails) design composed of Al

alloy. The heat sink is shown in Figure 5 can be obtained through Thermalloy Inc. by ref-

erencing part number 2338B.

Figure 5. Heat Sink Example

TS68040 Datasheet(PDF) 14 Page - ATMEL Corporation