300mA Low Dropout Regulators with Micropower Quiescent Current and Shutdown

The LT1521/LT1521-3/LT1521-3.3/LT1521-5 are low dropout regulators with micropower quiescent current and shutdown. These devices are capable of supplying 300mA of output current with a dropout voltage of 0.5V.Designed for use in battery-powered systems, the low quiescent current, 12μA operating and 6μA in shutdown, makes them an ideal choice. The quiescent current is well controlled; it does not rise in dropout as it does with many other low dropout PNP regulators.

Other features of the LT1521/LT1521-3/LT1521-3.3/LT1521-5 include the ability to operate with very small output capacitors. They are stable with only 1.5μF on the output while most older devices require between 10μF and 100μF for stability. Small ceramic capacitors can be used, enhancing manufacturability. Also, the input may be connected to voltages lower than the output voltage, including negative voltages, without reverse current flow from output to input. This makes the LT1521 series ideal for backup power situations where the output is held high and the input is low or reversed. Under these conditions only 5μA will flow from the output pin to ground.

APPLICATIONS

* Low Current Regulator

* Regulator for Battery-Powered Systems

* Post Regulator for Switching Supplies

* Dropout Voltage: 0.5V

* Output Current: 300mA

* Quiescent Current: 12µA

* No Protection Diodes Needed

* Adjustable Output from 3.8V to 20V

* Fixed Output Voltages: 3V, 3.3V, 5V