The thermal shutdown circuit protects the LDO against excessive heat in the system, either resulting from current limit or high ambient temperature.

The output of the LDO turns off when the LDO temperature (junction temperature, T_J) exceeds the rising thermal shutdown temperature. The output turns on again after T_J decreases below the falling thermal shutdown temperature.

A high power dissipation across the device, combined with a high ambient temperature (T_A), can cause T_J to be greater than or equal to T_sd, triggering the thermal shutdown and causing the output to fall to 0 V. The LDO can cycle on and off when thermal shutdown is reached under these conditions.

Continuously triggering thermal shutdown can degrade long-term reliability.