SBVS254D February 2018 – August 2019 TPS7A05
The device uses a PMOS pass transistor to achieve low dropout. When (VIN – VOUT) is less than the dropout voltage (VDO), the PMOS pass transistor is in the linear region of operation, and the input-to-output resistance of the device is the drain-to-source resistance of the PMOS pass transistor. VDO scales with the output current and changes with temperature because the PMOS pass transistor functions like a resistor in dropout mode. For a graph of dropout voltage, see Figure 22. As with any linear regulator, PSRR and the transient response degrade as (VIN – VOUT) approaches dropout operation. See Figure 23 for dropout performance.