LT1129/LT1129-3.3/LT1129-5 Micropower Low Dropout Regulators with Shutdown FEATURESDESCRIPTION n 400mV Dropout Voltage The LT®1129/LT1129-3.3/LT1129-5 are micropower low n 700mA Output Current dropout regulators with shutdown. The devices are capable n 50μA Quiescent Current of supplying 700mA of output current with a dropout n No Protection Diodes Needed voltage of 400mV at maximum output. Designed for use n Adjustable Output from 3.8V to 30V in battery-powered systems, the low quiescent current, n 3.3V and 5V Fixed Output Voltages 50μA operating and 16μA in shutdown, make them an ideal n Controlled Quiescent Current in Dropout choice. The quiescent current does not rise in dropout as n Shutdown it does with many other low dropout PNP regulators. n 16μA Quiescent Current in Shutdown Other features of the LT1129 /LT1129-3.3/LT1129-5 include n Stable with 3.3μF Output Capacitor the ability to operate with small output capacitors. They n Reverse Battery Protection are stable with only 3.3μF on the output while most older n No Reverse Output Current devices require between 10μF and 100μF for stability. Also n Thermal Limiting the input may be connected to ground or a reverse voltage n Surface Mount SOT-223 and DD-Pak Packages without reverse current fl ow from output to input. This makes the LT1129/LT1129-3.3/LT1129-5 ideal for backup APPLICATIONS power situations where the output is held high and the input is at ground or reversed. Under these conditions, n Low Current Regulator only 16μA will fl ow from the output pin to ground. The n Regulator for Battery-Powered Systems devices are available in 5-lead TO-220, 5-lead DD-Pak and n Post Regulator for Switching Supplies 3-lead SOT-223 packages. n 5V to 3.3V Logic Regulator L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. TYPICAL APPLICATION5V Supply with ShutdownDropout Voltage 0.6 5 1 5V OUT IN OUT 500mA 0.5 LT1129-5 + VIN > 5.5V 3.3μF 2 SOLID TANTALUM SENSE 0.4 4 SHDN GND 0.3 3 0.2 DROPOUT VOLTAGE (V) VSHDN (PIN 4) OUTPUT < 0.25 OFF 0.1 > 2.8 ON 112935 TA01 NC ON 0 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 OUTPUT CURRENT (A) 112935 TA02 112935ff 1