3
LT1185
1185ff
The ● denotes specifications which apply over the operating temperature range, otherwise specifications are at T
A
= 25°C.
Adjustable version, V
IN
= 7.4V, V
OUT
= 5V, I
OUT
= 1mA, R
LIM
= 4.02k, unless otherwise noted.
PARAMETER CONDITIONS MIN TYP MAX UNITS
Load Regulation (Note 7) I
OUT
= 5mA to 3A 0.05 0.3 %
V
IN
– V
OUT
= 1.5V to 10V, V
OUT
= 5V
Line Regulation (Note 7) V
IN
– V
OUT
= 1V to 20V, V
OUT
= 5V 0.002 0.01 %/V
Minimum Input Voltage I
OUT
= 1A (Note 4), V
OUT
= V
REF
4.0 V
I
OUT
= 3A 4.3 V
Internal Current Limit (See Graph for 1.5V ≤ V
IN
– V
OUT
≤ 10V 3.3 3.6 4.2 A
Guaranteed Curve) (Note 12)
● 3.1 4.4 A
V
IN
– V
OUT
= 15V ● 2.0 3.0 4.2 A
V
IN
– V
OUT
= 20V ● 1.0 1.7 2.6 A
V
IN
– V
OUT
= 30V ● 0.2 0.4 1.0 A
External Current Limit 5k ≤ R
LIM
≤ 15k, V
OUT
= 1V ● 15k A•Ω
Programming Constant (Note 11)
External Current Limit Error 1A ≤ I
LIM
≤ 3A 0.02 I
LIM
0.06 I
LIM
+ 0.03 A
R
LIM
= 15k • A/I
LIM
● 0.04 I
LIM
0.09 I
LIM
+ 0.05 A
Quiescent Supply Current I
OUT
= 5mA, V
OUT
= V
REF
● 2.5 3.5 mA
4V ≤ V
IN
≤ 25V (Note 5)
Supply Current Change with Load V
IN
– V
OUT
= V
SAT
(Note 10) ● 25 40 mA/A
V
IN
– V
OUT
≥ 2V ● 10 25 mA/A
REF Pin Shutoff Current ● 0.4 2 7 µA
Thermal Regulation (See Applications V
IN
– V
OUT
= 10V 0.005 0.014 %/W
Information) I
OUT
= 5mA to 2A
Reference Voltage Temperature Coefficient (Note 8) 0.003 0.01 %/°C
Thermal Resistance Junction to Case TO-3 Control Area 1 °C/W
Power Transistor 3 °C/W
TO-220 Control Area 1 °C/W
Power Transistor 3 °C/W
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2: Reference voltage is guaranteed both at nominal conditions (no
load, 25°C) and at worst-case conditions of load, line, power and
temperature. An intermediate value can be calculated by adding the effects
of these variables in the actual application. See the Applications
Information section of this data sheet.
Note 3: Dropout voltage is tested by reducing input voltage until the
output drops 1% below its nominal value. Tests are done at 0.5A and 3A.
The power transistor looks basically like a pure resistance in this range so
that minimum differential at any intermediate current can be calculated by
interpolation; V
DROPOUT
= 0.25V + 0.25Ω • I
OUT
. For load current less than
0.5A, see graph.
Note 4: “Minimum input voltage” is limited by base emitter voltage drive
of the power transistor section, not saturation as measured in Note 3. For
output voltages below 4V, “minimum input voltage” specification may limit
dropout voltage before transistor saturation limitation.
Note 5: Supply current is measured on the ground pin, and does not
include load current, R
LIM
, or output divider current.
Note 6: The 25W power level is guaranteed for an input-output voltage of
8.3V to 17V. At lower voltages the 3A limit applies, and at higher voltages
the internal power limiting may restrict regulator power below 25W. See
graphs.
Note 7: Line and load regulation are measured on a pulse basis with a
pulse width of ≈ 2ms, to minimize heating. DC regulation will be affected
by thermal regulation and temperature coefficient of the reference. See
Applications Information section for details.
Note 8: Guaranteed by design and correlation to other tests, but not
tested.
Note 9: T
JMIN
= 0°C for the LT1185C, –40°C for LT1185I, and –55°C for
the LT1185M. Power transistor area and control circuit area have different
maximum junction temperatures. Control area limits are T
JMAX
= 125°C for
the LT1185C and LT1185I and 150°C for the LT1185M. Power area limits
are 150°C for LT1185C and LT1185I and 175°C for LT1185M.
Note 10: V
SAT
is the maximum specified dropout voltage;
0.25V + 0.25 • I
OUT
.
Note 11: Current limit is programmed with a resistor from REF pin to GND
pin. The value is 15k/I
LIM
.
Note 12: For V
IN
– V
OUT
= 1.5V; V
IN
= 5V, V
OUT
= 3.5V. V
OUT
= 1V for all
other current limit tests.
ELECTRICAL CHARACTERISTICS
