8.3.6 Thermal Sense

The TPS2553-Q1 device has a self-protection feature using two independent thermal sensing circuits that monitor the operating temperature of the power switch. It disables the operation if the temperature exceeds recommended operating conditions. The TPS2553-Q1 device operates in constant-current mode during an overcurrent condition, which increases the voltage drop across the power-switch. The power dissipation in the package is proportional to the voltage drop across the power switch, which increases the junction temperature during an overcurrent condition. The first thermal sensor turns off the power switch when the die temperature exceeds 135°C (minimum) and the part is in current-limit. Hysteresis is built into the thermal sensor, and the switch turns on after the device has cooled approximately 10 °C.

The TPS2553-Q1 device also has a second ambient thermal sensor. The ambient thermal sensor turns off the power-switch when the die temperature exceeds 155°C (minimum) regardless of whether the power switch is in current-limit and will turn on the power switch after the device has cooled approximately 10 °C. The TPS2553-Q1 device continues to cycle off and on until the fault is removed.

The open-drain fault reporting output FAULT is asserted (active low) immediately during an overtemperature shutdown condition.