Now designers of portable and battery-powered products can get unprecedented performance from TI's latest generation of low dropout (LDO) voltage regulators: our new TPS71xx family. In place of the traditional pnp pass element, these new LDOs use an integrated PMOS pass transistor to achieve the lowest dropout voltage available today. This, in combination with their extremely low quiescent currents, yields a more efficient voltage regulator that can significantly extend battery life.
Because the PMOS pass transistor is voltage-driven, the TPS71xx's already low quiescent currents (typically 285 ľA) remain virtually constant up to the specified 500 mA load range, even when in dropout. Bipolar LDOs typically experience a large increase in quiescent currents when in dropout, often leading to sudden and rapid discharge of low batteries. The TPS71xx PMOS pass transistor acts like a small resistor, so at lighter loads the dropout voltage is even lower (the TPS7150 has only 32 mV max dropout under a 100 mA load). Lower dropout also means longer regulated system operation for improved performance.
TI's LinBiCMOS process yields superior performance: the TPS71xx achieves a ± 2% output voltage tolerance over full line, load and temperature changes. Other features, like a 0.5 ľA sleep mode for added power savings, a power-good indicator that can be used for power-on resets, and the ultra-thin TSSOP packaging make the TPS71xx appealing for new portable designs.
The TPS71xx family includes three fixed-output-voltage options - 3.3-V, 4.85-V, and 5-V - and an adjustable device (from 1.2 V to 9.75 V). The 4.85-V TPS7148 is especially attractive for 5-V systems, where regulating to the absolute minimum limit gives critical added operating time.
All devices are available in DIP, SOIC, and TSSOP packages.
See article Integrated LDO and supervisor
Vol 11, Spring, 1995