General information

STPA002

20/24

DocID024368 Rev 3

5.5

Heat sink definition

Assuming we have a dissipated power of 26 W (e.g. in the worst case situation of frequent

clipping occurrence, with music signal), considering Tj max is 150 °C and assuming ambient

temperature is 70 °C, the available temperature gap for a correct dissipation is 80 °C.

This means the thermal resistance of the system Rth has to be 80 °C/26 W = 3 °C/W.

The junction to case thermal resistance is 1 °C/W. So the heat sink thermal resistance

should be approximately 2 °C/W. This would avoid any thermal shutdown occurrence even

after long-term and full-volume operation.