thermal shut-down
the presence of a thermal limiting circuit offers the
following advantages:
1. an overload on the output (even if it is permanent),
or an above limit ambient temperature can
be easily supported since the tj cannot be
higher than 150°c.
2. the heatsink can have a smaller factor of safety
compared with that of a conventional circuit.
there is no possibility of device damage due to
high junction temperature. if for any reason, the

junction temperature increases up to 150°c, the
thermal shut-down simply reduces the power
dissipation at the current consumption.
the maximum allowable power dissipation depends
upon the size of the external heatsink (i.e. its
thermal resistance); fig. 22 shows this dissipable
power as a function of ambient temperature for
different thermal resistance.