FEATURES
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LT1175
500mA Negative
Low Dropout Micropower
Regulator
DESCRIPTIO
The LT
庐
1175 is a negative micropower low dropout regu-
lator. It features 45碌A quiescent current, dropping to
10碌A 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 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.
Minimum Input-to-Output Voltage
1.0
INPUT-TO-OUTPUT VOLTAGE (V)
Stable with Wide Range of Output Capacitors
Operating Current: 45
碌
A
Shutdown Current: 10碌A
Adjustable Current Limit
Positive or Negative Shutdown Logic
Low Voltage Linear Dropout Characteristics
Fixed 5V and Adjustable Versions
Tolerates Reverse Output Voltage
APPLICATIO S
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Analog Systems
Modems
Instrumentation
A/D and D/A Converters
Interface Drivers
Battery-Powered Systems
, LTC and LT are registered trademarks of Linear Technology Corporation.
TYPICAL APPLICATIO
Typical LT1175 Connection
T
J
= 25掳C
I
LIM2
, I
LIM4
TIED TO V
IN
0.8
+
C
IN
*
SHDN
鈥揤
IN
INPUT
I
LIM2
LT1175-5
I
LIM4
GND
SENSE
OUT
+
C
OUT
鈮?/div>
0.1碌F
鈥?V
UP TO 500mA
0.6
0.4
0.2
*C
IN
IS NEEDED ONLY IF REGULATOR IS MORE THAN 6" FROM
INPUT SUPPLY CAPACITOR. SEE APPLICATIONS INFORMATION
1175 TA01
SECTION FOR DETAILS
0
0
0.1
0.2 0.3 0.4
0.5
OUTPUT CURRENT (A)
0.6
0.7
U
U
U
1175 TA02
1
1
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4
5
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10
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