Due to the nature of the current limit circuit architecture, when the TLV758P initiates dropout operation with V_DO= 130 mV, the R_S resistor consumes a voltage between 60 mV and 70 mV. Hence, the sense device does not have sufficient drain-to-source voltage (V_DS), which causes the sense current to decrease. When the sense current decreases, the maximum current limit range increases.

During bench testing, the TLV758P regulator was capable of supplying a current level near 900 mA during dropout operation. After the current exceeds 900 mA and enters current limit protection mode, the TLV758P current limit circuit limits the current to a value within the I_CL range between 530 mA and 865 mA. #FIG_ABP_VG4_HWB and #FIG_XS5_ZG4_HWB show this behavior verified using simulation data .

With process and temperature variation results from simulation, shown in #FIG_BPT_KH4_HWB, the TLV758P was forced to a V_OUT of 4.0 V. When operating in the dropout region (V_IN is in a range between 4.1 V and 4.2 V) and V_OUT = 4.0 V, then the current limit value can increase to approximately 1.2 A. After that current limit engages, a regulated current limit range between 640 mA up to 810 mA which is within the range listed in the Electrical Characteristics table.

Similarly, #FIG_MJK_R34_HWB shows simulation data for V_OUT = 2.5 V. When the input voltage (V_IN ) is in deep dropout, the current limit value increases, in this case, close to 1.1 A. This reaction shows that the behavior is not dependent on the output voltage of the LDO regulator. After the input voltage starts increasing, the current limit returns to within the range between 620 mA and 800 mA showing that the device regulates the output current to a range within the TLV758P data sheet specifications.