LT1121_07 Datasheet, PDF (1/16 Pages) Linear Technology – Micropower Low Dropout Regulators with Shutdown

FEATURES
■ _{0.4V Dropout Voltage}
■ _{150mA Output Current}
■ _{30μA Quiescent Current}
■ _{No Protection Diodes Needed}
■ _{Adjustable Output from 3.75V to 30V}
■ _{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}
■ _{Available in the 8-Lead SO, 8-Lead PDIP, 3-Lead}
SOT-23 and 3-Lead TO-92 Packages
U
APPLICATIO S
■ _{Low Current Regulator}
■ _{Regulator for Battery-Powered Systems}
■ _{Post Regulator for Switching Supplies}
TYPICAL APPLICATIO
5V Battery-Powered Supply with Shutdown
8 _IN
1
OUT
3.3V_OUT
150mA
+
5V
LT1121-3.3
1μF
SOLID TANTALUM
5 _SHDN
GND
3
V_SHDN (PIN 5) OUTPUT
<0.25
OFF
>2.8
ON
NC
ON
LT1121 • TA01
LT1121/LT1121-3.3/LT1121-5
Micropower Low Dropout
Regulators with Shutdown
DESCRIPTIO
The LT^®1121/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 oper-
ating 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
regulators.
Other features of the LT1121/LT1121-3.3/LT1121-5 in-
clude the ability to operate with very small output capaci-
tors. 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.
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
Dropout Voltage
0.5
0.4
0.3
0.2
0.1
0
0 20 40 60 80 100 120 140 160
OUTPUT CURRENT (mA)
LT1121 • TA02
1121fe
1