The TLV755P has an internal current limit that protects the regulator during fault conditions. The current limit is a hybrid scheme with brick wall until the output voltage is less than 0.4V × V_OUT(NOM). When the voltage drops below 0.4V × V_OUT(NOM), a foldback current limit is implemented that scales back the current as the output voltage approaches GND. When the output shorts, the LDO supplies a typical current of I_SC. The output voltage is not regulated when the device is in current limit. In this condition, the output voltage is the product of the regulated current and the load resistance. When the device output shorts, the PMOS pass transistor dissipates power [(V_IN – V_OUT) × I_SC] until thermal shutdown is triggered and the device turns off. After the device cools down, the internal thermal shutdown circuit turns the device back on. If the fault condition continues, the device cycles between current limit and thermal shutdown.

The foldback current-limit circuit limits the current that is allowed through the device to current levels lower than the minimum current limit at nominal V_OUT current limit (I_CL) during start-up. See Figure 5-26 for typical current limit values. If the output is loaded by a constant-current load during start-up, or if the output voltage is negative when the device is enabled, then the load current demanded by the load potentially exceeds the foldback current limit and the device does not rise to the full output voltage. For constant-current loads, disable the output load until the output rises to the nominal voltage.

Excess inductance causes the current limit to oscillate. Minimize the inductance to keep the current limit from oscillating during a fault condition.