AD590

Rev. E | Page 9 of 16

Table 4. Thermal Resistance

(°C/Watt)

τ (sec)1

Medium

H

F

H

F

Aluminum Block

30

10

0.6

0.1

Stirred Oil2

42

60

1.4

0.6

Moving Air3

With Heat Sink

45

–

5.0

–

Without Heat Sink

115

190

13.5

10.0

Still Air

With Heat Sink

191

–

108

–

Without Heat Sink

480

650

60

30

instantaneous temperature change.

The time response of the AD590 to a step change in

temperature is determined by the thermal resistances and the

medium, because it includes anything that is in direct thermal

contact with the case. The single time constant exponential

curve of Figure 15 is usually sufficient to describe the time

response, T (t). Table 4 shows the effective time constant, τ, for

several media.

τ

4

τ

TIME

Figure 15. Time Response Curve