LT1121

Features:

0.4V Dropout Voltage
150mA Output Current
30^_µA Quiescent Current
No Protection Diodes Needed
Adjustable Output from 3.8V to 20V
3.3V and 5V Fixed Output Voltages
Controlled Quiescent Current in Dropout
Shutdown
16µA Quiescent Current in Shutdown
Stable with 0.33µF Output Capacitor
Reverse Battery Protection
No Reverse Current with Input Low
Thermal Limiting


Application

Low Current Regulator
Regulator for Battery-Powered Systems
Post Regulator for Switching Supplies


Pinout




Specifications

Input Voltage ......................................................  ±30V*
Output Pin Reverse Current .................................  10mA
Adjust Pin Current ...............................................  10mA
Shutdown Pin Input Voltage (Note 1) ........  6.5V, 0.6V
Shutdown Pin Input Current (Note 1) ..................  20mA
Output Short-Circuit Duration .........................  Indefinite
Storage Temperature Range ................ 65°C to 150°C
Operating Junction Temperature Range (Note 2)
LT1121C-X .........................................       0°C to 125°C
LT1121I-X .....................................        40°C to 125°C
Lead Temperature (Soldering, 10 sec) .................300°C


Description

The LT1121/LT1121-3.3/LT1121-5 are micropower low dropout regulators with shutdown. These devices are capable of supplying 150mA of output current with a dropout voltage of 0.4V. Designed for use in battery-powered systems, the low quiescent current, 30µA operating and 16µA 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 egulators.

Other features of the LT1121/LT1121-3.3/LT1121-5 include the ability to operate with very small output capacitors. They are stable with only 0.33µF on the output while most older devices require between 1µF and 100µF for stability. Small ceramic capacitors can be used, enhancing manufacturability. Also the input may be connected to ground or a reverse voltage without reverse current flow from output to input. This makes the LT1121 series ideal for backup power situations where the output is held high and the input is at ground or reversed. Under these conditions only 16µA will flow from the output pin to ground.