ZHCSGF3B July 2017 – January 2019 TPS7A92
PRODUCTION DATA.
The TPS7A92 contains a thermal shutdown protection circuit to turn off the output current when excessive heat is dissipated in the LDO. Thermal shutdown occurs when the thermal junction temperature (TJ) of the pass-FET exceeds 160°C (typical). Thermal shutdown hysteresis assures that the LDO again resets (turns on) when the temperature falls to 140°C (typical). The thermal time-constant of the semiconductor die is fairly short, and thus the output turns on and off at a high rate when thermal shutdown is reached until power dissipation is reduced.
The internal protection circuitry of the TPS7A92 is designed to protect against thermal overload conditions. The circuitry is not intended to replace proper heat sinking. Continuously running the TPS7A92 into thermal shutdown degrades device reliability.
For reliable operation, limit junction temperature to a maximum of 125°C. To estimate the thermal margin in a given layout, increase the ambient temperature until the thermal protection shutdown is triggered using worst-case load and highest input voltage conditions. For good reliability, thermal shutdown must occur at least 35°C above the maximum expected ambient temperature condition for the application. This configuration produces a worst-case junction temperature of 125°C at the highest expected ambient temperature and worst-case load.