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
The LT1129/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 drop-
out 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.
APPLICATI
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Low Current Regulator
Regulator for Battery-Powered Systems
Post Regulator for Switching Supplies
5V to 3.3V Logic Regulator
TYPICAL APPLICATI
5V Supply with Shutdown
0.6
5
IN
LT1129-5
4
SENSE
SHDN
GND
3
2
OUT
1
5V OUT
500mA
0.5
V
IN
> 5.5V
+
3.3µF
SOLID TANTALUM
DROPOUT VOLTAGE (V)
0.4
0.3
0.2
0.1
0
0
0.1
0.5
0.2 0.3 0.4
OUTPUT CURRENT (A)
0.6
0.7
V
SHDN
(PIN 4) OUTPUT
< 0.25
OFF
> 2.8
ON
NC
ON
LT1129 • TA01
U
Dropout Voltage
LT1129 • TA02
UO
UO
1
LINER [ LINEAR TECHNOLOGY ]
