LT1185 Datasheet, PDF (1/16 Pages) Linear Technology – Low Dropout Regulator

LT1185
Low Dropout Regulator
FEATURES
s _{Low Resistance Pass Transistor: 0.25Ω}
s _{Dropout Voltage: 0.75V at 3A}
s _{±1% Reference Voltage}
s _{Accurate Programmable Current Limit}
s _{Shutdown Capability}
s _{Internal Reference Available}
s _{Standard 5-Lead Packages}
s _{Full Remote Sense}
s _{Low Quiescent Current: ≈ 2.5mA}
s _{Good High Frequency Ripple Rejection}
DESCRIPTIO
The LT^®1185 is a 3A low dropout regulator with adjustable
current limit and remote sense capability. It can be used as
a positive output regulator with floating input or as a
standard negative regulator with grounded input. The
output voltage range is 2.5V to 25V, with ±1% accuracy on
the internal reference voltage.
The LT1185 uses a saturation-limited NPN transistor as
the pass element. This device gives the linear dropout
characteristics of an FET pass element with significantly
less die area. High efficiency is maintained by using special
anti-saturation circuitry that adjusts base drive to track
load current. The “on resistance” is typically 0.25Ω.
Accurate current limit is programmed with a single 1/8W
external resistor, with a range of zero to three amperes. A
second, fixed internal limit circuit prevents destructive
currents if the programming current is accidentally over-
ranged. Shutdown of the regulator output is guaranteed
when the program current is less than 1µA, allowing
external logic control of output voltage.
The LT1185 has all the protection features of previous LTC
regulators, including power limiting and thermal shut-
down. The 4-lead TO-3 package is specified for –55°C to
150°C operation and the 5-lead TO-220 is specified over
0°C to 125°C.
, LTC and LT are registered trademarks of Linear Technology Corporation.
TYPICAL APPLICATI
5V, 3A Regulator with 3.5A Current Limit
+
+
V_IN
6V TO 16V
C2
2µF
TANT
R_LIM*
4.3k
REF
GND
FB
–
V_IN
LT1185
V_OUT
+
R1
2.37k
+
R2
2.67k
C1
V_OUT
2µF 5V AT 3A
TANT
–
LT1185 • TA01
*CURRENT LIMIT = 15k/R_LIM = 3.5A
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
0
Dropout Voltage
T_J = 25°C
T_J = 125°C
T_J = –55°C
1
2
3
4
LOAD CURRENT (A)
LT1185 • TA02
1