LT1129/LT1129-3.3/LT1129-5
Micropower Low Dropout
Regulators with Shutdown
FEATURES DESCRIPTION
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400mV Dropout Voltage
The LT 1129/LT1129-3.3/LT1129-5 are micropower low
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700mA Output Current
dropout regulators with shutdown. The devices are capable
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50A Quiescent Current
of supplying 700mA of output current with a dropout
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No Protection Diodes Needed
voltage of 400mV at maximum output. Designed for use
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Adjustable Output from 3.8V to 30V
in battery-powered systems, the low quiescent current,
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3.3V and 5V Fixed Output Voltages
50A operating and 16A in shutdown, make them an ideal
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Controlled Quiescent Current in Dropout
choice. The quiescent current does not rise in dropout as
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Shutdown
it does with many other low dropout PNP regulators.
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16A Quiescent Current in Shutdown
Other features of the LT1129 /LT1129-3.3/LT1129-5 include
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Stable with 3.3F Output Capacitor
the ability to operate with small output capacitors. They
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Reverse Battery Protection
are stable with only 3.3F on the output while most older
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No Reverse Output Current
devices require between 10F and 100F for stability. Also
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Thermal Limiting
the input may be connected to ground or a reverse voltage
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Surface Mount SOT-223 and DD-Pak Packages
without reverse current ow 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
APPLICATIONS
input is at ground or reversed. Under these conditions,
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Low Current Regulator
only 16A will ow from the output pin to ground. The
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Regulator for Battery-Powered Systems
devices are available in 5-lead TO-220, 5-lead DD-Pak and
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Post Regulator for Switching Supplies
3-lead SOT-223 packages.
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5V to 3.3V Logic Regulator
L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
TYPICAL APPLICATION
5V Supply with Shutdown Dropout Voltage
0.6
5 1
5V OUT
IN OUT
500mA
0.5
+
LT1129-5
3.3F
V > 5.5V
IN
2 SOLID TANTALUM
0.4
SENSE
4
SHDN
GND 0.3
3
0.2
V (PIN 4) OUTPUT
SHDN
0.1
< 0.25 OFF
> 2.8 ON
112935 TA01
NC ON
0
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7
OUTPUT CURRENT (A)
112935 TA02
112935ff
1
DROPOUT VOLTAGE (V)LT1129/LT1129-3.3/LT1129-5
ABSOLUTE MAXIMUM RATINGS (Note 1)
Input Voltage ...................................................... 30V* Storage Temperature Range .................. 65C to 150C
Output Pin Reverse Current ................................. 10mA Operating Junction Temperature Range (Note 3)
Sense Pin Current ................................................ 10mA LT1129C-X .......................................... 0C to 125C
Adjust Pin Current ................................................ 10mA LT1129C-X Extended Temperature Range
Sense Pin, Adjust Pin Reverse Voltage ............... 0.6V (Note 12) ....................................... 40C to 125C
Shutdown Pin Input Voltage (Note 2) ......... 6.5V, 0.6V LT1129I-X(Note 12) ......................... 40C to 125C
Shutdown Pin Input Current (Note 2) .................. 20mA LT1129MP-X(Note 12) ..................... 55C to 125C
Output Short-Circuit Duration .......................... Inde nite Lead Temperature (Soldering, 10 sec) ..................300C
* For applications requiring input voltage ratings greater than 30V, contact the factory.
PIN CONFIGURATION
TOP VIEW
1 20 GND
GND
GND 2 19 GND
FRONT VIEW
TOP VIEW
GND 3 18 GND
5 V
4 GND IN
GND 17 OUTPUT 1 8 V
IN
4 SHDN
SENSE/
GND 5 16 GND TAB
2 7 GND
ADJ*
IS 3 GND
6 15 GND
GND
GND 3 6 GND
GND
2 SENSE/ADJ*
OUT 7 14 IN
NC 4 5 SHDN
1 OUTPUT
SENSE 8 13 SHDN
S8 PACKAGE
Q PACKAGE
9 GND
GND 12
8-LEAD PLASTIC SO
5-LEAD PLASTIC DD
GND 10 11 GND
*PIN 2 = SENSE FOR LT1129-3.3/LT1129-5
*PIN 2 = SENSE FOR LT1129-3.3/LT1129-5
= ADJ FOR LT1129
= ADJ FOR LT1129
F PACKAGE
= 60C/W
= 30C/W JA
20-LEAD PLASTIC TSSOP JA
NOTE: ALL GROUND PINS ARE INTERNALLY CONNECTED
= 40C/W
JA
OBSOLETE PACKAGE
FRONT VIEW
FRONT VIEW
5 V
IN
3 OUTPUT
4 SHDN
TAB
TAB
IS 3 GND
IS
2 GND
GND
GND 2 SENSE/ADJ*
1
1 OUTPUT
V
IN
T PACKAGE
ST PACKAGE
5-LEAD PLASTIC TO-220
3-LEAD PLASTIC SOT-223
*PIN 2 = SENSE FOR LT1129-3.3/LT1129-5 = ADJ FOR LT1129
= 50C/W
JA
= 50C/W
JA
ORDER INFORMATION
LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE
LT1129CS8#PBF LT1129CS8#TRPBF 1129 8-Lead Plastic SO 0C to 125C
LT1129IS8#PBF LT1129IS8#TRPBF 1129I 8-Lead Plastic SO 40C to 125C
LT1129CS8-3.3#PBF LT1129CS8-3.3#TRPBF 11293 8-Lead Plastic SO 0C to 125C
LT1129IS8-3.3#PBF LT1129IS8-3.3#TRPBF 1129I3 8-Lead Plastic SO 40C to 125C
LT1129CS8-5#PBF LT1129CS8-5#TRPBF 11295 8-Lead Plastic SO 0C to 125C
112935ff
2