The operational area of an LDO is limited by the dropout voltage, output current, junction temperature, and input voltage. The recommended area for continuous operation for a linear regulator can be separated into the following parts, and is shown in Figure 8-13:

• Limited by dropout: Dropout voltage limits the minimum differential voltage between the input and the output (V_IN – V_OUT) at a given output current level.
• Limited by rated output current: The rated output current limits the maximum recommended output current level. Exceeding this rating causes the device to fall out of specification.
• Limited by thermals: The shape of the slope is given by Equation 11. The slope is nonlinear because the junction temperature of the LDO is controlled by the power dissipation across the LDO; therefore, when V_IN – V_OUT increases, the output current must decrease in order to ensure that the rated junction temperature of the device is not exceeded. Exceeding this rating can cause the device to fall out of specifications and reduces long-term reliability.
• Limited by V_IN range: The rated input voltage range governs both the minimum and maximum of V_IN – V_OUT.

Figure 8-13 Continuous Operation Slope Region Description

Figure 8-14 to Figure 8-19 show the recommended area of operation curves for this device on a JEDEC-standard high-K board with a R_θJA = 35.4°C/W, as given in the Section 6.5 table.

Figure 8-14 Recommended Area for Continuous Operation for V_OUT = 0.9 V With Bias

Figure 8-16 Recommended Area for Continuous Operation for V_OUT = 1.8 V

Figure 8-18 Recommended Area for Continuous Operation for V_OUT = 3.3 V

Figure 8-15 Recommended Area for Continuous Operation for V_OUT = 1.2 V With Bias

Figure 8-17 Recommended Area for Continuous Operation for V_OUT = 2.5 V

Figure 8-19 Recommended Area for Continuous Operation for V_OUT = 5.0 V