The thermal protection behavior can be split up into two categories of events that can occur. Thermal Behavior for Auto-Retry Version shows each of these categories.

1. Relative thermal shutdown: the device is enabled into an overcurrent event. The output current rises up to the I_ILIM level and the FLT goes low. With this large amount of current going through the junction temperature of the FET increases rapidly with respect to the controller temperature. When the power FET temperature rises T_REL amount above the controller junction temperature ΔT = T_FET – T_CON > T_REL, the device shuts down. For auto-retry version, after t_RETRY, the part tries to restart itself. Latch version requires EN to be toggled to re-enable the channel. The FLT is asserted until the fault condition is cleared.
2. Absolute thermal shutdown: The device is still enabled in an overcurrent event. However, in this case the junction temperature rises up and hits an absolute reference temperature, T_ABS, and then shuts down. For auto-retry version, the device does not recover until both T_J < T_ABS – T_hys and the t_RETRY timer has expired. For latch version, toggling EN is required to re-enable the channel.

Figure 7-19 Thermal Behavior for Auto-Retry Version