LT1175
500mA Negative
Low Dropout Micropower
Regulator
DESCRIPTION
FEATURES
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Operating Current: 45μA
Adjustable Current Limit
Low Voltage Linear Dropout Characteristics
Stable with Wide Range of Output Capacitors
Shutdown Current: 10μA
Positive or Negative Shutdown Logic
Fixed 5V and Adjustable Versions
Tolerates Reverse Output Voltage
Available in 8-pin PDIP and SO Packages, 3-lead
SOT-223, 5-Pin Surface Mount DD and Through-Hole
TO-220 Packages
APPLICATIONS
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Analog Systems
Modems
Instrumentation
A/D and D/A Converters
Interface Drivers
Battery-Powered Systems
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
The LT®1175 is a negative micropower low dropout
regulator. It features 45μA quiescent current, dropping
to 10μA in shutdown. A new reference amplifier topology
gives precision DC characteristics along with the ability to
maintain good loop stability with an extremely wide range
of output capacitors. Very low dropout voltage and high
efficiency are obtained with a unique power transistor
anti-saturation design. Adjustable and fixed 5V versions
are available.
Several new features make the LT1175 very user-friendly.
The SHDN pin can interface directly to either positive or
negative logic levels. Current limit is user-selectable at
200mA, 400mA, 600mA and 800mA. The output can be
forced to reverse voltage without damage or latchup. Unlike some earlier designs, the increase in quiescent current
during a dropout condition is actively limited.
The LT1175 has complete blowout protection with current
limiting, power limiting and thermal shutdown. Special
attention was given to the problem of high temperature
operation with micropower operating currents, preventing
output voltage rise under no-load conditions. The LT1175
is available in 8-pin PDIP and SO packages, 3-lead SOT223 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
+
+
CIN*
–VIN
SHDN
GND
VIN
ILIM2
ILIM4
SENSE
COUT
≥ 0.1μF
–5V
UP TO 500mA
LT1175-5
OUTPUT
*CIN IS NEEDED ONLY IF REGULATOR IS MORE THAN 6" FROM
INPUT SUPPLY CAPACITOR. SEE APPLICATIONS INFORMATION
1175 TA01
SECTION FOR DETAILS
INPUT-TO-OUTPUT VOLTAGE (V)
Typical LT1175 Connection
TJ = 25°C
ILIM2, ILIM4 TIED TO VIN
0.8
0.6
0.4
0.2
0
0
0.1
0.2 0.3 0.4
0.5
OUTPUT CURRENT (A)
0.6
0.7
1175 TA02
1175ff
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