PTN78000A thermal shutdown

PTN78000AXX thermal sense is activated when the top side semiconducctors diode and FET is about 130°C.

Tom  

Over temperature Protection

A thermal shutdown mechanism protects the module's internal circuitry against excessively high temperatures. A rise in temperature may be the result of a drop in airflow, a high ambient temperature, or a sustained current limit condition. If the junction temperature of the internal control IC rises excessively, the module turns itself off, reducing the output voltage to zero. The module instantly restarts when the sensed temperature decreases by a few degrees.

 Over-temperature protection is a last resort mechanism to prevent damage to the module. It should not be relied on as permanent protection against thermal stress. Always operate the module within its temperature derated limits, for the worst-case operating conditions of output current, ambient temperature, and airflow. Operating the module above these limits, albeit below the thermal shutdown temperature reduces the long-term reliability of the module.