Thermal management

AN3031

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Doc ID 16144 Rev 1

and

Equation 11

+ 24 V x 6 mA – 5 V x 4.5 mA + 0.7 V x 13 mA = 548 mW

If we consider the same conditions as those above, maximum ambient temperature of 100

°C, we must achieve a thermal resistance lower than 91 °C / W. The SCLT3-8BT8 works

correctly at these conditions. Connecting the input in reverse polarity conditions, the total

power dissipation decreases. It allows biasing of all the SCLT3-8BT8 inputs by reverse

polarity current without risk of component damage.

Special care must be taken on the serial resistor ratings. During normal operation/worst-

case conditions, the power ratings of the serial resistors are:

●

●

During a reverse polarity connection at 25 °C, the resistors must be able to dissipate:

To increase the reliability of the resistors, considering long-term reverse polarity, the

following options are suggested:

1.

Parallel connection of two (or more) resistors

2.

Use of high power-rating resistors

3.

required surge immunity voltage (e.g. 1 or 2 kV), or to use additional Transil

(bidirectional) at the application supply voltage terminal (e.g. SM15T36CA).