LT1521-5_15 Datasheet, PDF (1/16 Pages) Linear Technology – 300mA Low Dropout Regulators with Micropower Quiescent Current and Shutdown

LT1521/LT1521-3
LT1521-3.3/LT1521-5
300mA Low Dropout
Regulators with Micropower
Quiescent Current and Shutdown
FEATURES
s _{Dropout Voltage: 0.5V}
s _{Output Current: 300mA}
s _{Quiescent Current: 12µA}
s _{No Protection Diodes Needed}
s _{Adjustable Output from 3.8V to 20V}
s _{Fixed Output Voltages: 3V, 3.3V, 5V}
s _{Controlled Quiescent Current in Dropout}
s _{Shutdown IQ = 6µA}
s _{Reverse Battery Protection}
s _{No Reverse Current}
s _{Thermal Limiting}
U
APPLICATIO S
s _{Low Current Regulator}
s _{Regulator for Battery-Powered Systems}
s _{Post Regulator for Switching Supplies}
DESCRIPTIO
The LT^®1521/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 con-
nected to voltages lower than the output voltage, including
negative voltages, without reverse current flow from out-
put 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.
, LTC and LT are registered trademarks of Linear Technology Corporation.
TYPICAL APPLICATIO
5V Battery-Powered Supply with Shutdown
8 _IN
OUT ¹
6V
1µF
LT1521-5
5 _SHDN
SENSE ²
GND
3
5V
300mA
+
1.5µF
V_SHDN (PIN 5)
<0.25
>2.80
NC
OUTPUT
OFF
ON
ON
LT1521 • TA01
Dropout Voltage
0.6
0.5
0.4
0.3
0.2
0.1
0
0 50 100 150 200 250 300
OUTPUT CURRENT (mA)
LT1521 • TA02
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