鈮?/div>
2.5mA
Good High Frequency Ripple Rejection
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 鈥渙n resistance鈥?is typically 0.25鈩?
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 1碌A, 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 鈥?5擄C to
150擄C operation and the 5-lead TO-220 is specified over
0擄C to 125擄C.
DESCRIPTIO
The LT1185 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
鹵1%
accuracy on
the internal reference voltage.
TYPICAL APPLICATI
+
5V, 3A Regulator with 3.5A Current Limit
+
C2
2碌F
TANT
R
LIM
*
4.3k
REF
GND
FB
V
IN
鈥?V
OUT
(V)
V
IN
6V TO 16V
鈥?/div>
V
OUT
LT1185
V
OUT
*CURRENT LIMIT = 15k/R
LIM
= 3.5A
UO
U
+
R1
2.37k
Dropout Voltage
1.6
1.4
1.2
+
C1
2碌F
TANT
R2
2.67k
V
OUT
5V AT 3A
1.0
T
J
= 25擄C
0.8
0.6
0.4
T
J
= 鈥?5擄C
0.2
0
0
1
2
LOAD CURRENT (A)
LT1185 鈥?TA02
T
J
= 125擄C
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