AN3031

Thermal management

Doc ID 16144 Rev 1

21/28

Considering the above application structure and the following conditions:

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the overall chip power dissipation is:

Equation 8

In case of a maximum allowed ambient temperature equal to 100 °C, the thermal resistance

must be lower than:

Equation 9

correctly at this ambient temperature.

In the final application we must consider other cases also. One example is spurious

connection of one channel to negative voltage.

approximately 0.7 V at 16 mA.

All of the other inputs work correctly.

The total power dissipation in this case can be calculated by with the equation:

Equation 10

R

THJAMAX

ΔT

JA

–

P

D

------------------

150

° C 100° C

–

0.599W

------------------------------------------

83

° CW

⁄

==

=

I

REV

V

CC

V

REV

–

R

IN

-------------------------------

30

0.7V

–

2200

Ω

-------------------------

13mA

=

==