8.1.7.2 Recommended Area for Continuous Operation

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 shown in Figure 41, and can be separated into the following regions:

• Dropout voltage limits the minimum differential voltage between the input and the output (V_IN – V_OUT) at a given output current level.
• 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.
  • Equation 5 provides the shape of the slope. 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 41. Region Description of Continuous Operation Regime