LT1129/LT1129-3.3/LT1129-5
Micropower Low Dropout
Regulators with Shutdown
FEATURES
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DESCRIPTIO
0.4V Dropout Voltage
700mA Output Current
50µA Quiescent Current
No Protection Diodes Needed
Adjustable Output from 3.8V to 30V
3.3V and 5V Fixed Output Voltages
Controlled Quiescent Current in Dropout
Shutdown
16µA Quiescent Current in Shutdown
Stable with 3.3µF Output Capacitor
Reverse Battery Protection
No Reverse Output Current
Thermal Limiting
Surface Mount SOT-223 and DD Packages
The LT
®
1129/LT1129-3.3/LT1129-5 are micropower low
dropout regulators with shutdown. The devices are ca-
pable of supplying 700mA of output current with a dropout
voltage of 0.4V at maximum output. Designed for use in
battery-powered systems the low quiescent current, 50µA
operating and 16µA in shutdown, make them an ideal
choice. The quiescent current does not rise in dropout as
it does with many other low dropout PNP regulators.
Other features of the LT1129 /LT1129-3.3/LT1129-5 in-
clude the ability to operate with small output capacitors.
They are stable with only 3.3µF on the output while most
older devices require between 10µF and 100µF for stabil-
ity. Also the input may be connected to ground or a reverse
voltage without reverse current flow from output to input.
This makes the LT1129/LT1129-3.3/LT1129-5 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. The
devices are available in 5-lead TO-220, 5-lead DD and
3-lead SOT-223 packages.
, LTC and LT are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
APPLICATIO S
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Low Current Regulator
Regulator for Battery-Powered Systems
Post Regulator for Switching Supplies
5V to 3.3V Logic Regulator
TYPICAL APPLICATIO
5
1
5V Supply with Shutdown
0.6
IN
LT1129-5
OUT
5V OUT
500mA
DROPOUT VOLTAGE (V)
V
IN
> 5.5V
4
+
2
0.5
0.4
0.3
0.2
0.1
SENSE
SHDN
GND
3
3.3µF
SOLID TANTALUM
V
SHDN
(PIN 4) OUTPUT
< 0.25
OFF
> 2.8
ON
NC
ON
LT1129 • TA01
0
0
0.1
0.5
0.2 0.3 0.4
OUTPUT CURRENT (A)
0.6
0.7
U
Dropout Voltage
LT1129 • TA02
U
U
112935fc
1
LINEAR [ LINEAR INTEGRATED SYSTEMS ]
