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 is given in Figure 7-3 and can be separated into the following parts:

• Dropout voltage limits the minimum differential voltage between the input and the output (V_IN – V_OUT) at a given output current level. See the Dropout Operation section for more details.
• The rated output currents limits the maximum recommended output current level. Exceeding this rating causes the device to fall out of specification.
• The rated junction temperature limits the maximum junction temperature of the device. Exceeding this rating causes the device to fall out of specification and reduces long-term reliability.
  • The shape of the slope is given by Equation 4. The slope is nonlinear because the maximum-rated junction temperature of the LDO is controlled by the power dissipation across the LDO; thus when V_IN – V_OUT increases the output current must decrease.
• The rated input voltage range governs both the minimum and maximum of V_IN – V_OUT.

Figure 7-3 shows the recommended area of operation for this device on a JEDEC-standard high-K board with a R_θJA as given in the Thermal Information table.

Figure 7-3 Region Description of Continuous Operation Regime