LT1175
500mA Negative
Low Dropout Micropower
Regulator
FEATURES DESCRIPTION
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Operating Current: 45A
The LT 1175 is a negative micropower low dropout
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Adjustable Current Limit
regulator. It features 45A quiescent current, dropping
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Low Voltage Linear Dropout Characteristics
to 10A in shutdown. A new reference ampli er topology
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Stable with Wide Range of Output Capacitors
gives precision DC characteristics along with the ability to
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Shutdown Current: 10A
maintain good loop stability with an extremely wide range
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Positive or Negative Shutdown Logic
of output capacitors. Very low dropout voltage and high
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Fixed 5V and Adjustable Versions
ef ciency are obtained with a unique power transistor
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Tolerates Reverse Output Voltage
anti-saturation design. Adjustable and xed 5V versions
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Available in 8-pin PDIP and SO Packages, 3-lead
are available.
SOT-223, 5-Pin Surface Mount DD and Through-Hole
Several new features make the LT1175 very user-friendly.
TO-220 Packages
The SHDN pin can interface directly to either positive or
negative logic levels. Current limit is user-selectable at
APPLICATIONS
200mA, 400mA, 600mA and 800mA. The output can be
forced to reverse voltage without damage or latchup. Un-
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Analog Systems
like some earlier designs, the increase in quiescent current
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Modems
during a dropout condition is actively limited.
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Instrumentation
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A/D and D/A Converters
The LT1175 has complete blowout protection with current
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Interface Drivers
limiting, power limiting and thermal shutdown. Special
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Battery-Powered Systems
attention was given to the problem of high temperature
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
operation with micropower operating currents, preventing
Technology Corporation. All other trademarks are the property of their respective owners.
output voltage rise under no-load conditions. The LT1175
is available in 8-pin PDIP and SO packages, 3-lead SOT-
223 as well as 5-pin surface mount DD and through-hole
TO-220 packages. The 8-pin SO package is specially
constructed for low thermal resistance.
TYPICAL APPLICATION Minimum Input-to-Output Voltage
1.0
T = 25C
Typical LT1175 Connection J
I , I TIED TO V
LIM2 LIM4 IN
0.8
+ +
C
OUT
C *
IN
0.1F 0.6
SHDN GND
5V
V SENSE
V IN
IN
UP TO 500mA
0.4
I LT1175-5
LIM2
I OUTPUT
LIM4
0.2
*C IS NEEDED ONLY IF REGULATOR IS MORE THAN 6" FROM
IN
0
INPUT SUPPLY CAPACITOR. SEE APPLICATIONS INFORMATION
0 0.2 0.3 0.4 0.5 0.7
1175 TA01 0.1 0.6
SECTION FOR DETAILS
OUTPUT CURRENT (A)
1175 TA02
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INPUT-TO-OUTPUT VOLTAGE (V)LT1175
(Note 1)
ABSOLUTE MAXIMUM RATINGS
Input Voltage (Transient 1 sec, Note 12) ...................25V Output Reverse Voltage ..............................................2V
Input Voltage (Continuous) .......................................20V SHDN Pin to GND Pin Voltage (Note 3) ........13.5V, 20V
Input-to-Output Differential Voltage (Note 13) ..........20V SHDN Pin to V Pin Voltage .............................30V, 5V
IN
5V SENSE Pin (with Respect to GND Pin) ......... 2V, 10V Operating Junction Temperature Range (Note 2)
ADJ SENSE Pin LT1175C ................................................. 0C to 125C
(with Respect to OUTPUT Pin) ...................20V, 0.5V LT1175I .............................................. 40C to 125C
5V SENSE Pin LT1175MP .......................................... 55C to 125C
(with Respect to OUTPUT Pin) ......................20V, 7V Storage Temperature Range .................. 65C to 150C
Lead Temperature (Soldering, 10 sec)...................300C
PIN CONFIGURATION
FRONT VIEW
TOP VIEW FRONT VIEW
3 GND
V V
1 8 5 SHDN
IN IN
4
GND
TAB TAB IS
I 2 7 I
LIM2 LIM4
2 V
3 V
IS V IN
IN IN
2
V SENSE
OUTPUT 3 6 SHDN IN
1 OUTPUT
1 OUTPUT
SENSE 4 GND
5
Q PACKAGE
ST PACKAGE
5-LEAD PLASTIC DD-PAK
N8 PACKAGE
3-LEAD PLASTIC SOT-223
8-LEAD PDIP
= 27C/W TO 60C/W
JA
= 50C/W
JA
= 80C/W TO 120C/W DEPENDING ON PC MOUNTING.
JA 2
WITH BACKPLANE AND 10cm
DEPENDING ON PC BOARD LAYOUT SEE DATA SHEET FOR DETAILS
TOPSIDE LAND SOLDERED TO TAB
TOP VIEW
V 1 8 V
IN IN
FRONT VIEW
I 2 7 I
LIM2 LIM4
5
SHDN
OUTPUT 3 6 SHDN
4
GND
SENSE GND
4 5
3 V
IN
2 SENSE
S8 PACKAGE
1 OUTPUT
8-LEAD PLASTIC SO
TAB IS
= 60C/W TO 100C/W
JA
V
DEPENDING ON PC BOARD LAYOUT IN
T PACKAGE
5-LEAD PLASTIC TO-220
PINS 1, 8 ARE INTERNALLY CONNECTED TO DIE ATTACH PADDLE FOR HEAT SINKING.
= 50C/W, = 5C/W
JA JC
ELECTRICAL CONTACT CAN BE MADE TO EITHER PIN. FOR BEST THERMAL RESISTANCE,
PINS 1, 8 SHOULD BE CONNECTED TO AN EXPANDED LAND THAT IS OVER AN INTERNAL
OR BACKSIDE PLANE.
SEE APPLICATIONS INFORMATION
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